Jungfraujoch/docs/RUGNUX.md

# rugnux

`rugnux` is the **offline** crystallographic data-analysis tool of Jungfraujoch — the
data-processing half of the system (see [Naming](NAMING.md) for where the name comes from).
It takes an existing HDF5 dataset, runs the full analysis pipeline — spot finding, indexing,
geometry refinement, Bragg integration and (optionally) scaling and merging — and writes the
results to a `_process.h5` file, plus reflection files (`.mtz`/`.cif`/`.hkl`) when merging is
requested.

It runs the *same* analysis code as the online and interactive tools, just driven from the
command line over a file rather than a live detector stream.

```
rugnux {<options>} <input.h5>
```

Run it with no arguments to print the usage.

> **Note.** `rugnux` is under very active development. This page describes the tool and
> its options at a high level; the authoritative, always-current list of options is the program's
> own usage message — run `rugnux` with no arguments.

## Installation

`rugnux` is a **single self-contained executable**. It needs no CUDA toolkit, no Qt, and no
Jungfraujoch service running anywhere; on a machine with an NVIDIA GPU it needs the NVIDIA
**driver**, and without one it still runs on the CPU.

### From the package repositories (RHEL / Rocky / Ubuntu)

On a distribution covered by the [package repositories](REPOSITORIES.md), `rugnux` is a package of
its own:

```
sudo dnf install rugnux          # RHEL / Rocky 8 and 9
sudo apt install rugnux          # Ubuntu 22.04 / 24.04
```

It installs `/usr/bin/rugnux` and depends on nothing from the acquisition side — no broker, no
detector libraries, no Qt — so it can go on a machine that only processes data.

> **Upgrading from rc.163 or earlier.** `/usr/bin/rugnux` used to belong to the `jfjoch-viewer`
> package. The `rugnux` package declares that the file has moved, so installing it upgrades an old
> `jfjoch-viewer` in the same transaction instead of failing on the duplicate path. If your
> `jfjoch-viewer` is pinned to an old version, unpin it or remove it first.

### From the release archive

For a machine no package manager covers — or for Windows and Arm, which have no repository — take
the archive for your architecture from the Gitea release page:

| Archive | For |
| --- | --- |
| `rugnux-<version>-linux-x86_64-cuda12.tgz` | 64-bit Intel/AMD Linux. Built on RHEL 8, so it runs on any newer Linux |
| `rugnux-<version>-linux-aarch64-cuda13.tgz` | 64-bit Arm Linux — NVIDIA GH200 and DGX Spark. Built on Ubuntu 24.04, so it needs glibc 2.39 or newer. Cross-compiled and **not yet exercised on Arm hardware** |
| `rugnux-<version>-win64-cuda13.zip` | 64-bit Windows |

**The archive has no top-level directory** — it unpacks straight into `bin/` and `share/`. Always
give `tar` a destination of its own, or it will scatter those into whatever directory you are in:

```
mkdir -p /opt/rugnux-1.0.0
tar xzf rugnux-1.0.0-linux-x86_64-cuda12.tgz -C /opt/rugnux-1.0.0
/opt/rugnux-1.0.0/bin/rugnux            # prints the usage
```

What you get is:

```
bin/rugnux                                  the program
share/doc/jfjoch_rugnux/LICENSE             GPLv3
share/doc/jfjoch_rugnux/THIRD_PARTY_NOTICES.md
share/doc/jfjoch_rugnux/licenses/           verbatim licence texts of the bundled dependencies
```

Nothing is written outside that directory, nothing needs root, and several versions can sit side by
side. To remove it, delete the directory. Put `bin/` on your `PATH` if you want to type `rugnux`
rather than the full path.

> **Mixing the two.** If a `rugnux` package is also installed, `/usr/bin/rugnux` will normally win
> on `PATH`. Put the archive's `bin/` first, or call it by its full path, to be sure which one you
> are running — `rugnux` prints its version on every run.

### GPU support

The released archives are CUDA builds. They need only an NVIDIA **driver** on the host — 525.60.13
or newer for the CUDA 12 archive, 580.65.06 or newer for the CUDA 13 ones — and no CUDA toolkit,
because everything CUDA is linked statically. With no GPU or no driver, `rugnux` reports zero CUDA
devices and falls back to the CPU path, which works but is far slower and offers only the `fftw`
indexer. A **V100 needs the CUDA 12 archive**; which generations each build covers is in
[Release contents ▸ GPU generations and the NVIDIA driver](RELEASE_CONTENTS.md#gpu-generations-and-the-nvidia-driver).

### Building from source

`rugnux` alone, without the server stack or Qt:

```
cmake -S . -B build -DJFJOCH_RUGNUX_ONLY=ON -DCMAKE_BUILD_TYPE=Release \
      -DCMAKE_CXX_FLAGS="-march=x86-64-v3" -DCMAKE_C_FLAGS="-march=x86-64-v3"
cmake --build build -j$(nproc) --target rugnux
```

The binary lands in `build/rugnux/rugnux`. Two dependencies must come from the system — **zlib** and
**Eigen ≥ 3.4** (`zlib-devel` and `eigen3-devel`, or their Debian equivalents); everything else is
downloaded during the first configure, which therefore needs network access. `cmake --build build
--target package` produces the same `.tgz` the release ships. The `-march` flag is not set by the
build system on purpose, so a plain build is slower than the released one on the CPU-bound stages —
see the note in `CMakeLists.txt`.

## Where it fits among the three analysis tools

| Tool | Mode | Driven by | Output |
| --- | --- | --- | --- |
| [`jfjoch_broker`](JFJOCH_BROKER.md) | Online, real-time streaming analysis on FPGA + GPU | HTTP/REST + ZeroMQ | Live results and statistics, images streamed to [`jfjoch_writer`](JFJOCH_WRITER.md) |
| [`jfjoch_viewer`](JFJOCH_VIEWER.md) | Interactive, on-screen exploration | Qt desktop application | On screen; a processing job can write the same files as `rugnux` |
| **`rugnux`** | **Offline batch processing of a stored dataset** | **Command-line interface** | **`_process.h5`, and `.mtz`/`.cif`/`.hkl` when merging** |

Use `rugnux` to re-analyse data after acquisition, to experiment with processing
parameters, or to produce merged intensities for downstream structure solution.

## Hardware

As with the rest of Jungfraujoch, **serious performance requires an NVIDIA GPU**. The CUDA build
provides the GPU fast-feedback indexer (`ffbidx`) and the GPU FFT indexer (`fft`); without CUDA
only the CPU `fftw` indexer is available. With a GPU present most of the per-image pipeline runs on
the device — bitshuffle+LZ4 decompression, image preprocessing, azimuthal integration, spot finding,
prediction and Bragg integration — as does rotation scaling and merging, with CPU implementations as
the fallback where there is no GPU. The thread count (`-N`) governs the CPU side of all of it.

The released CUDA builds need only an NVIDIA **driver** on the host, no CUDA toolkit: 525.60.13 or
newer for the CUDA 12 artefacts (RHEL 8 packages, the x86_64 `rugnux` archive) and 580.65.06 or
newer for the CUDA 13 ones (RHEL 9, Ubuntu, the aarch64 and Windows `rugnux` archives). Which GPU
generations each artefact supports — a V100 in particular works only with the CUDA 12 build — is in
[Release contents ▸ GPU generations and the NVIDIA driver](RELEASE_CONTENTS.md#gpu-generations-and-the-nvidia-driver).

## Input and output

**Input** is a single Jungfraujoch HDF5 master file (NXmx-based). Spots are always found by `rugnux`
itself, including for the two-pass rotation first pass — the spot lists a dataset may already carry
were found online, at the acquisition's threshold and with its ice-band spots already discarded, so
reusing them would hide the spot-finding settings from the lattice search.

**Output** (controlled by `-o, --output-prefix`, default `output`):

- `<prefix>_process.h5` — NXmx-compliant HDF5 with derived metadata (spots, indexing,
  integration, azimuthal integration, per-image statistics). See
  [HDF5 / NeXus data format](HDF5.md) for the layout. Written by default only when **not** merging
  (i.e. under `--no-merge`); add `--write-process-h5` to also write it when merging.
  It does not copy the images: `/entry/data/data` is a virtual dataset over the *input* files, so
  the input has to stay where it was for the pictures to be readable, and the pixel metadata
  (`bit_depth_readout`, `underload_value`, the dataset type) describes those files rather than the
  signed 32-bit container rugnux processes in.
- Merging is **on by default** (`--no-merge` disables it). The merged reflections are written in
  **three** formats — each has its uses downstream:
  - `<prefix>.mtz` — CCP4 MTZ (`IMEAN`/`I(+)`/`I(-)`, French–Wilson `F`, `FreeR_flag`) for the CCP4 /
    phenix reflection tools.
  - `<prefix>.cif` — mmCIF, for deposition and as the self-describing native format (also carries the
    merging statistics, ISa, twinning and radiation-damage indicators).
  - `<prefix>.hkl` — SHELX **HKLF 4** text (`h k l I σ(I)`, fixed `3I4,2F8.2`), the direct input for
    **SHELXC / ANODE / SHELXD**. Bijvoet mates are written separately (`I(+)` at `+hkl`, `I(-)` at
    `-hkl`) so the anomalous signal is preserved; intensities are put on a common scale so the largest
    value fits the fixed-width field (the absolute scale is irrelevant to SHELXC/ANODE), and the file
    ends with the `0 0 0` terminator record.

  All three carry the **refined unit cell** (from rotation indexing) and the **space group determined
  from systematic absences** (constrained to the indexed lattice symmetry).
- `<prefix>_unmerged.mtz` — **opt-in** (`--export-unmerged`): the integrated observations *before*
  merging, as an unmerged MTZ in POINTLESS's column layout, so the data can be scaled and merged by
  **aimless**, **pointless**, **careless** or `iotbx.merging_statistics` instead of by rugnux. See
  [The unmerged export](#the-unmerged-export) below. `--export-unmerged-partials` writes
  `<prefix>_unmerged_partials.mtz`, one row per image, instead of summing.
- `<prefix>_report.txt` — the **results report**: what the run determined, in a form both a person and
  a beamline script can read. Always written, next to the files above. See
  [The results report](#the-results-report) below.

Merged statistics (⟨I/σ⟩, CC1/2, completeness, …), the error model and timing are printed to the
console. By default the written resolution is trimmed automatically where CC1/2 falls off
(`--resolution-cutoff cc-logistic`, CC1/2 target 0.30); set `--scaling-high-resolution` to fix the
limit by hand, or `--resolution-cutoff off` to keep the full range.

### Reflection-file conventions

**mmCIF.** Standard items carry their standard meanings — `_refln.intensity_meas` / `_intensity_sigma`,
the `pdbx_I_plus`/`pdbx_I_minus` and `pdbx_F_plus`/`pdbx_F_minus` anomalous pairs, `_reflns.*` and
`_reflns_shell.*` for the merging statistics, `_reflns.B_iso_Wilson_estimate` for the Wilson B, and
`_cell.*` / `_diffrn_radiation_wavelength.wavelength` for the geometry.

Anything rugnux reports that has no standard item is written under a **`jfjoch_`** prefix, inside the
standard category it belongs to. That is a deliberate choice: a reader that does not know these items
ignores them, and one that does can find them without guessing.

| item | meaning |
|---|---|
| `_reflns.jfjoch_diffrn_ISa` | Asymptotic I/σ in **XDS's sense**: the whole-range `1/√(a·b)` of the error model, so it can be read directly against a `CORRECT.LP` |
| `_reflns.jfjoch_diffrn_ISa_asymptotic` | The **strong-reflection** tier — the counting-subtracted scatter of well-measured groups. XDS has no equivalent, and it can only ever be the more optimistic of the two. Rotation path only |
| `_reflns.jfjoch_error_model_a`, `_b` | The error model in XDS's convention, `σ² = a(σ₀² + b·I²)`, so the ISa above is re-derivable from the file rather than taken on trust |
| `_reflns.jfjoch_second_moment_I` | Twinning second moment ⟨I²⟩/⟨I⟩² — 2.00 untwinned, 1.50 for a perfect twin |
| `_reflns.jfjoch_L_test_mean_abs_L`, `_L_test_mean_L_squared` | Padilla–Yeates L-test. ⟨\|L\|⟩ is 0.500 untwinned / 0.375 for a perfect twin; ⟨L²⟩ is 0.333 / 0.200. Written only when the test found pairs |
| `_reflns.jfjoch_radiation_damage_relative_B` | Relative *B* from the first to the last rotation batch (Ų); positive is the usual direction, high-resolution intensity fading with dose |
| `_jfjoch_radiation_damage_batch.*` | Per-batch loop: `id`, `rotation_start_deg`, `relative_B` |
| `_diffrn_detector.jfjoch_distance_mm`, `_jfjoch_beam_center_x_pxl`, `_jfjoch_beam_center_y_pxl` | The refined detector geometry actually used, which is not otherwise recoverable from the reflection file |
| `_reflns.pdbx_aniso_B_tensor_eigenvalue_1..3`, `_pdbx_aniso_B_tensor_eigenvector_*` | The anisotropy tensor, eigen-decomposed. Eigenvalues are **relative to the weakest direction** (so the third is 0 and the first is the anisotropic Δ*B*), because only the deviatoric part is determined; eigenvectors are in the PDB orthogonalisation convention. Not written for a cubic Laue class, where symmetry forces Δ*B* to be zero |
| `_reflns.jfjoch_aniso_delta_B`, `_jfjoch_aniso_delta_B_linear` | The anisotropic Δ*B*, and the part of it that actually follows exp(−½ **s**ᵀ*B***s**). The second is what the verdict is gated on |
| `_reflns.jfjoch_aniso_d_min_1..3` | Diffraction limit (Å) along each principal direction. A comment marks a value that is the edge of the measured data rather than the crystal's own limit |
| `_reflns.jfjoch_aniso_shape`, `_jfjoch_aniso_floor`, `_jfjoch_aniso_significance`, `_jfjoch_aniso_verdict` | The resolution signature of the deficit, the data set's own systematic-error floor, Δ*B*<sub>linear</sub> over that floor, and the resulting verdict. Each carries its vocabulary as a comment |

> **Compatibility note.** Before rc.161, `_reflns.jfjoch_diffrn_ISa` carried the *asymptote*, not the
> whole-range value. There is no version marker inside the file, so a number taken from an older
> `.cif` is not comparable with one taken from a newer one.

**SHELX HKLF 4** (`<prefix>.hkl`). Fixed-format `3I4,2F8.2` — `h k l I σ(I)`, one record per
reflection, terminated by a `0 0 0` record — which is what **SHELXC**, **SHELXD** and **ANODE**
expect. Two properties worth knowing before using it:

- **Bijvoet mates are written separately**, `I(+)` at `+hkl` and `I(-)` at `-hkl`, so the anomalous
  differences survive into SHELXC; a reflection with no anomalous split is written once, as its mean.
- **Intensities are rescaled** by a single global factor so the largest value fits the `F8.2` field.
  `I` and `σ(I)` share that factor, so every ratio — and therefore the anomalous signal — is
  untouched, but the absolute scale is not meaningful. This matters only if you intend to compare
  magnitudes with another file; SHELXC and ANODE use ratios alone.

## The unmerged export

`--export-unmerged` writes `<prefix>_unmerged.mtz`: every integrated observation, before scaling and
merging, in the column layout POINTLESS writes and **aimless**, **pointless**, **careless** and
`iotbx.merging_statistics` read. It is written in `--mode mx` and `--mode scale` alike, off by
default, and does not replace anything — rugnux still writes its own merged files in the same run.

Use it to scale the data with a different program, to have pointless give an independent opinion on
the space group, or to compare rugnux's merge against another one on identical input.

**Columns.** `H K L M/ISYM BATCH I SIGI FRACTIONCALC XDET YDET ROT LP FLAG` — POINTLESS's own set —
plus four rugnux extras, `DELPHI` (offset from the centre of the rocking curve), `ZETA` (the Lorentz
geometry of that curve), `BGMEAN` and `BGVAR` (the background that was subtracted, and its variance).
`BATCH` is the image ordinal plus one, and a batch header is written for every batch that carries an
observation. `M/ISYM` records both the symmetry operation and the Friedel hand, so the index as
measured is recoverable from the index as stored.

**What has been applied to the intensities, and what has not.** `I` and `SIGI` carry the
**Lorentz-polarization factor and nothing else**; the factor itself is in the `LP` column, so raw
counts are `I/LP`. LP is applied because it is per-observation geometry that varies by more than two
orders of magnitude across a sweep and no reader can reconstruct it. Deliberately *not* applied:
the **partiality is not divided out** (it is reported in `FRACTIONCALC`), and the **per-image scale is
not applied at all** — those programs fit their own scale model, and handing them pre-scaled data
would have them fit a correction to a correction. No resolution cut, outlier rejection or ice-ring
filtering is applied either.

**Partials.** On a rotation run the partials of each reflection are summed into one full, using the
same rule rugnux's own 3D combine uses — consecutive frames no more than two apart — and the full is
written at the batch its rocking curve is centred on, with the summed rocking-curve fraction in
`FRACTIONCALC`. An event that caught less of its rocking curve than `--min-partiality` is not
written, exactly as in the merge. Summing is the default because a downstream program's own partial
handling is far more conservative than rugnux's: given raw partials, aimless accepted a small
fraction of the file and merged at a fraction of the multiplicity; given summed fulls it uses
essentially all of it. `--export-unmerged-partials` writes the unsummed form to
`<prefix>_unmerged_partials.mtz` for a program that would rather sum them itself. Stills have no
rocking events and are the same either way.

**Systematic absences.** Lattice-**centring** absences are not written; **screw and glide** absences
are. Prediction runs in a primitive setting so that the space-group search can test the centring,
but the interstitial reflections that leaves make a reading program take the lattice for primitive
and demote the group. Screw and glide absences are kept because they are the evidence the space
group was chosen on — deleting them would turn a reading program's test into an assumption. XDS and
DIALS draw the line in the same place.

**Scan axis.** The batch headers carry the goniometer axis **negated** relative to the one in the
input file. This is not a correction to the file: rugnux brings an observation made at angle φ back
to zero by rotating it by +φ, so the crystal itself turns by −φ, and an MTZ batch header records the
axis a batch's own increasing `PHI` turns the crystal about. With the sign as exported, pointless's
independently determined orientation matrix agrees with rugnux's to well under a degree.

## The results report

`<prefix>_report.txt` records **what the run determined**, next to the reflection files. It is
written on every `--mode mx` and `--mode scale` run that has an output prefix — there is no option
to enable or disable it. Two cases follow from that:

- An **empty output prefix** (`-o ""`, the "compute the statistics, persist nothing" mode) writes
  nothing, the report included.
- **`--no-merge`** still writes a report. It determined an indexing and a geometry result, and those
  are recorded; the merging section then says `MERGE= NOT_PERFORMED` rather than being omitted, so
  the absence is a statement and not something a reader has to infer.

The report is never allowed to fail a run: if it cannot be written (unwritable path, full disk) the
failure is logged as a warning and the run finishes normally.

### Format

The model is XDS's `CORRECT.LP`: prose and tables a crystallographer reads top to bottom, with a
structure a script can consume without parsing prose.

- **`KEY= value` assignment lines.** Every number worth extracting is one, so a consumer gets it with
  a single `grep '^ISA= '` and never has to read a sentence. Key names are stable.
- **Fixed-width tables** with a stable header row for anything that is genuinely tabular — the
  resolution shells, the space-group candidates, the sweep-quality ranges.
- **`WARNING:` lines**, one per finding, in plain English: `WARNING: Frames 500-600 out of beam
  (10.1 deg, scale 0.12 and CC 0.30 of the run, 2% scaled)`. `grep '^WARNING:'` finds every one.
- **Section banners** (`***…***` around a numbered title) delimiting the blocks.

`REPORT_VERSION=` is the format's own version. Key names, table columns and the reason vocabulary
below are an interface other software may depend on: they do not change without that number moving.

Sections, in order: `1. DATA SET`, `2. INDEXING`, `3. GEOMETRY POST-REFINEMENT` (rotation only),
`4. SPACE GROUP DETERMINATION`, `5. SCALING AND MERGING`, `6. TWINNING`, `7. RADIATION DAMAGE`,
`8. SWEEP QUALITY`, `9. DIFFRACTION ANISOTROPY`, `10. WARNINGS`.

**`SPOT_RESOLUTION_ESTIMATE=`** in section 1 is how far the merged data are expected to reach, read
off the found spots alone — no lattice, no integration, no merge — so it is there on a run that never
merges, and on a run that does it can be read against `INCLUDE_RESOLUTION_RANGE` in section 5. It is a
prediction, good to about 0.2 Å on rotation data; nothing is cut on it.

**Which pass.** A rotation run integrates twice — once at the geometry in the input file, then again
at the post-refined geometry — and can integrate a third time if a guard rejects the second pass.
There is **one** report, for the pass that became the canonical output, and `PASS=` /
`PASS_DECISION=` in section 1 say which pass that is and on what evidence, so no number in the file
is ambiguous about which geometry produced it.

**Not in the report:** timing, frame rates, thread counts, per-image progress and library banners.
Those are process, not result, and stay on stdout.

### Sweep quality and the reason vocabulary

Section 8 lists the stretches of the sweep over which the crystal delivered much less than the rest
of the run — the feedback a beamline control system needs to tell an operator that a crystal should
be recentred or recollected. Nothing is excluded on the strength of it; the frames still carry
signal, and this is a message for the beamline, not a filter.

```
SWEEP_QUALITY_STATUS= COMPUTED
SWEEP_QUALITY_COUNT= 1
SWEEP_QUALITY_REASONS= no_diffraction crystal_out_of_beam weak_diffraction loss_of_centring radiation_damage
SWEEP_ROTATION= 360.0
FLUX_PEAK_TO_TROUGH= 1.03
SCALE_MODULATION_PEAK_TO_TROUGH= 1.00

  FIRST_IMAGE   LAST_IMAGE   N_IMAGES  ROTATION  REASON                SEVERITY   SCALE      CC   INDEXED
  -----------  -----------  ---------  --------  --------------------  --------  ------  ------  --------
          500          600        101      10.1  crystal_out_of_beam       0.83    0.12    0.30      0.02
  -----------  -----------  ---------  --------  --------------------  --------  ------  ------  --------
```

`SWEEP_QUALITY_STATUS` distinguishes **`COMPUTED`** (the diagnostic ran; a count of 0 means the sweep
was clean throughout) from **`NOT_COMPUTED`** (it did not run — no scaling and merging, or stills
data). A consumer must not read a missing table or a zero count as "clean" without checking it.
`SWEEP_QUALITY_REASONS` lists the whole vocabulary this version can emit, so an unknown code is
distinguishable from a missing one.

| Reason code | Meaning |
|-------------|---------|
| `no_diffraction` | The range recorded essentially no diffraction from the indexed lattice. |
| `crystal_out_of_beam` | Frames were lost: over the range a per-image scale could be fitted far less often than over the run. |
| `weak_diffraction` | The frames all still index, but with much less intensity — the cause was not determined. |
| `loss_of_centring` | One cycle of modulation per revolution: the crystal is off the rotation axis. |
| `radiation_damage` | The range runs to the end of a sweep whose quality was already decaying. |

The vocabulary is **closed and stable**: a code is never renamed, and never reused for a different
meaning. New codes are only ever added, and adding one moves `REPORT_VERSION`.

The columns are: `FIRST_IMAGE`/`LAST_IMAGE` — inclusive, in processed-image ordinals (the numbering
of `<prefix>_image.dat` and of every other per-image array `rugnux` writes; with `-s`/`--stride` the
source image is `start + ordinal * stride`); `ROTATION` — the width of the range in degrees;
`SEVERITY` — the fraction of the run's typical diffracting power missing over the range, 0 (as good
as the run) to 1 (nothing at all); `SCALE` and `CC` — the range's mean per-image scale and
CC-to-merge relative to the run median; `INDEXED` — the fraction of the range's frames that were
scaled at all. Every range also appears as a `WARNING:` sentence in section 9.

The same finding is written **per image** into the `_process.h5` as `/entry/MX/sweepQuality`, when
one is written — see [HDF5](HDF5.md#41-entrymx--spot-finding-and-indexing-cxi-style).

### Diffraction anisotropy

Section 9 reports how much the fall-off with resolution depends on **direction**, and whether that is
established above the data set's own systematic error. It runs automatically on every merging run —
there is no flag — and it is a **description only**: no intensity is corrected, no reflection is
removed on a directional criterion, and the merged data and the written reflection files do not
depend on direction at all. The algorithm is in
[CPU/GPU data analysis ▸ Diffraction anisotropy](CPU_DATA_ANALYSIS.md).

Two different quantities are reported and they are not interchangeable. `ANISOTROPY_DELTA_B` is a
*rate* — the range of the principal components of the anisotropy tensor, on the ordinary
crystallographic *B* scale, so it is directly comparable with phenix.xtriage's `B_cart`, ctruncate's
anisotropic *B* and AIMLESS's anisotropic Δ*B*. `ANISOTROPY_D_MIN_PRINCIPAL` is where the signal
actually *runs out* along each principal direction. A crystal can have a large Δ*B* and almost no
spread in directional limit, or the reverse.

| key | meaning |
|---|---|
| `ANISOTROPY_VERDICT` | `DETECTED` \| `NOT_DETECTED` \| `CANNOT_DETERMINE` |
| `ANISOTROPY_FREE_DIRECTIONS` | Deviatoric directions the Laue class allows — 5 triclinic, 3 monoclinic, 2 orthorhombic, 1 tetragonal/trigonal/hexagonal, **0 cubic** |
| `ANISOTROPY_DELTA_B` | The anisotropic Δ*B* (Ų), fitted on intensities with nothing dropped |
| `ANISOTROPY_DELTA_B_LINEAR` | The part of it that follows exp(−½ **s**ᵀ*B***s**). **This is the number the verdict is gated on**, and the report says which of the two it is quoting |
| `ANISOTROPY_PRINCIPAL_B` | The three principal components, relative to the weakest |
| `ANISOTROPY_D_MIN_PRINCIPAL` | Diffraction limit (Å) along each principal direction — where ⟨I/σ(I)⟩ in a 20° cone about it falls through 2 |
| `ANISOTROPY_D_MIN_CENSORED` | One flag per direction. `1` means ⟨I/σ(I)⟩ never fell through 2, so the limit is the **edge of the measured data**, a bound and not a measurement. The prose marks it with a `<` |
| `ANISOTROPY_D_MIN_SPREAD` | Range of the three limits — itself a lower bound if any is censored |
| `ANISOTROPY_SHAPE` | `LINEAR` (a real Debye–Waller *B*) \| `FLAT` (the deficit does not follow a *B* at all, so Δ*B* may be an **under**-estimate) \| `CONVEX` (grows faster than a *B* can) \| `UNDETERMINED` (the verdict moved on rebinning) |
| `ANISOTROPY_FLOOR`, `ANISOTROPY_SIGNIFICANCE` | The data set's own systematic-error floor (Ų) and Δ*B*<sub>linear</sub> over it. Banded: below 2 not established, 2–3.5 marginal, above 3.5 established, above 5 strong |
| `ANISOTROPY_DETECTION_LIMIT` | The smallest Δ*B* that could have been established on these data. It is set by systematic error, not by counting, so it does **not** improve with more reflections or a longer exposure |
| `ANISOTROPY_N_OBSERVATIONS`, `ANISOTROPY_FORBIDDEN_Z`, `ANISOTROPY_SIGMA_SYSTEMATIC` | The unmerged observations the floor was measured on, that measurement against its own counting noise, and the floor before the counting part is added back |

**`CANNOT_DETERMINE` is a real answer, not an evasion.** The verdict is not measured against counting
statistics — real data carry systematic error far larger than that, and gating on counting error
reports anisotropy on data sets that have none. Instead the data set measures its own systematic
error in the tensor directions its Laue class *forbids*, where the true value is exactly zero
whatever the crystal is. Where that measurement cannot be made, the run says so and gives the
reason: a **triclinic** Laue class (no forbidden direction exists), an observed rotation under about
90°, merged data at the noise floor, a scale model carrying no dose term
(`--no-scaling-corrections`), or no unmerged observations. A **cubic** Laue class is different again
— symmetry forces Δ*B* to be exactly zero, and the run says that rather than reporting a measurement.

Where anisotropy is detected and the directional limits differ by more than 0.5 Å, a `WARNING:` line
says so, since refinement and map interpretation should allow for it.

## Validating against a model (`rugnux --model`)

Given a PDB atomic model of the same structure, `--model model.pdb` scales the model structure
factors to the merged amplitudes — fitting a flat bulk-solvent contribution and an overall
anisotropic *B* — and reports **R-work / R-free** and the mean 2Fo-Fc density at the atom centres.
It also writes `<prefix>_2fofc.ccp4`, `<prefix>_fofc.ccp4` and `<prefix>_maps.mtz` next to the
merged reflections. Nothing about the model is refined; it is only re-fractionalized into the data
cell, so a deposited model with a slightly different cell still lines up.

It is a *data-quality lens*, independent of the internal statistics: R-free measures the merged
intensities against external truth, where CC1/2 and R<sub>meas</sub> only measure them against
themselves. It also settles the two things merged intensities alone cannot: the enantiomorph (data
merged in P4<sub>1</sub>2<sub>1</sub>2 against a P4<sub>3</sub>2<sub>1</sub>2 model are reindexed
into the model's hand), and — when no reference MTZ has already fixed it — a merohedral indexing
ambiguity, by keeping the candidate reindexing with the lowest R-free.

## Re-scaling and re-merging (`rugnux --mode scale`)

The `scale` mode re-scales and merges the *already-integrated* reflections stored in a
`_process.h5` file, without re-running spot finding or integration. Use it to re-merge quickly with a
different space group, resolution limit, anomalous setting or reference MTZ. It reuses the same
`-o/-N/-s/-e/-S/-A/-B/-z/--scaling-*` options as the full run, and (unlike the full pipeline) does
not run a space-group search: it merges in the space group and unit cell the file records, and `-S`
/ `-C` override them. A `_process.h5` written before the group was stored carries none, and merges
in P1 unless `-S` says otherwise.

Where the full run re-seated the lattice — the space group it settled on is in a different setting
from the one each image was indexed in — the file records the change of basis as
`/entry/MX/reindexMatrix`, and `rugnux` applies it on read, so the reflections and the stored cell
describe the same frame. An older file that was affected by this cannot be repaired (the matrix is
not recoverable after the fact); such a file now stops with a message naming both cells and the
exact `-S`/`-C` override to merge it in its own setting, instead of failing inside the merge.

## Detector calibration from powder rings (`rugnux --mode calibration`)

The `calibration` mode determines the detector geometry — PONI *x*/*y*, the two tilts
rot1/rot2 and the distance — from the powder rings of a calibrant, and writes it as a
pyFAI **`<prefix>.poni`** file alongside a printed report of how far each parameter moved from
the header. Bragg data pin the beam centre worst (it is gauge-coupled to the crystal orientation);
a powder ring has no orientation to be coupled to, so this is the measurement that fixes it.

```
rugnux --mode calibration --calibrant lab6 -N 8 -o det LaB6_master.h5
```

`--calibrant` takes `lab6`, `agbh` (silver behenate), `ceo2`, `si` or `ice`, case-insensitively.
**`ice`** calibrates a real experiment against its own ice rings — no calibrant exposure needed —
and is the reason a calibrant is a list of ring positions rather than a unit cell: hexagonal ice
is P6<sub>3</sub>/mmc, so rings enumerated from its cell would include systematically absent ones.

`--calibration` picks how the rings are measured, and **both use the whole dataset** — `-s`/`-e`/`-t`
select which images:

- **`rings`** (default) sums the (*q* × azimuth) azimuthal profile over every processed image into
  one map and fits the ring arcs in it. A powder ring is an arc, not a set of spots, and the summed
  profile measures it at every azimuth with all the run's counts behind it. It needs the profile to
  be binned in azimuth, so this mode defaults `--azim-phi-bins` to 32.
- **`spots`** pools the found spots of every processed image and fits those. It determines the
  centre from scratch (a Hough circle vote, which quantises it to a whole pixel) and then refines.

Both routes read the ring position out of a binned profile or a spot centroid, so the radial
sampling matters: at a long detector distance the default 0.01 Å⁻¹ *q* bin is several pixels wide
and quantises the `rings` route accordingly — pass a finer `--azim-q-spacing` there (the total
*q* × azimuth bin count must stay under 65534).

The report prints the fitted geometry, the scatter of the ring points about the fitted rings and the
standard error that implies on the centre. That error is *formal*: it measures the scatter of the
points, not whether the rings themselves are trustworthy, so it stays small when a fit goes wrong
for a structural reason — one visible ring, or ice that is textured rather than smooth.

Both the PONI (the point of normal incidence, which is what a `.poni` file stores) and the direct
beam (where the beam lands, which is what most other programs call the beam centre) are printed.
They differ by *distance* × tan(rot) once the detector is tilted, which on a 0.3° tilt at 300 mm is
several pixels — enough to look like a disagreement with another program when there is none.

## Comparing the geometry with XDS

Every run logs the detector geometry a second time in **XDS's convention**, so it can be read
straight across against the `IDXREF.LP` / `CORRECT.LP` of an XDS run on the same data:

```
XDS convention: ORGX= 1091.00 ORGY= 1137.00 DETECTOR_DISTANCE= 75.0000
XDS convention: DIRECTION_OF_DETECTOR_X-AXIS= 1.000000 0.000000 0.000000
XDS convention: DIRECTION_OF_DETECTOR_Y-AXIS= 0.000000 1.000000 0.000000
XDS convention: INCIDENT_BEAM_DIRECTION= 0 0 1 X-RAY_WAVELENGTH= 1.000000 QX= QY= 0.075000
XDS convention: ROTATION_AXIS= -1.000000 0.000000 0.000000
```

XDS is never given this geometry — the [XDS plugin](SOFTWARE_INTEGRATION.md) supplies image data
only, and XDS refines its own from `XDS.INP` — which is what makes the comparison worth having. The
two laboratory frames coincide (x along increasing detector column, y along increasing row, z along
the beam), so the numbers are directly comparable, and a tilt appears as the two detector axis
vectors rather than as angles, which is how XDS reports it after refinement. Two things to keep in
mind: **`ORGX`/`ORGY` are 1-based**, because XDS counts pixels from 1 and Jungfraujoch from 0; and
they are the **PONI**, the same quantity Jungfraujoch's beam centre is — so no correction is needed —
but not the direct beam once the detector is tilted (see above).

## Quick start

### A first run, start to finish

Process a rotation sweep and merge it, with nothing assumed about the crystal:

```
rugnux -o myrun -N 32 /path/to/dataset_master.h5
```

`-o myrun` is the prefix every output file is named from, `-N 32` is the worker-thread count, and the
last argument is the **master** file of a Jungfraujoch dataset. That is the whole command — the
goniometer axis in the file tells rugnux this is a rotation sweep, the unit cell comes from indexing
the data, the space group from its systematic absences, and the resolution limit from where CC1/2
falls off.

Progress, statistics and timing go to the terminal. When it finishes you have five files next to
each other:

```
myrun.mtz            merged intensities + French-Wilson amplitudes, for CCP4 / phenix
myrun.cif            the same, as mmCIF - the self-describing format, and what to deposit
myrun.hkl            the same, as SHELX HKLF 4 - feed this to SHELXC / SHELXD / ANODE
myrun_report.txt     what the run determined: cell, space group, statistics, warnings
myrun_image.dat      one row per image, for plotting how the crystal behaved over the sweep
```

Read `myrun_report.txt` first — it is written for a person, top to bottom, and it says which space
group was chosen and on what evidence, how far the data go, and anything that needs attention. To
pull one number out of it in a script, every value is a `KEY= value` line:

```
grep '^SPACE_GROUP_NUMBER= '        myrun_report.txt
grep '^UNIT_CELL_CONSTANTS= '      myrun_report.txt
grep '^INCLUDE_RESOLUTION_RANGE= ' myrun_report.txt
grep '^ISA= '                      myrun_report.txt
grep '^WARNING:'                   myrun_report.txt
```

**Useful variations**, each independent of the others:

```
# tell it where the data really stop, if you already know - this sharpens the
# space-group search and the error model
rugnux -o myrun -N 32 --scaling-high-resolution 1.4 dataset_master.h5

# keep Friedel pairs apart, for anomalous work
rugnux -o myrun -N 32 -A dataset_master.h5

# a quick look at the first 200 images only
rugnux -o quicklook -N 32 -e 200 dataset_master.h5

# merge as usual, but also keep the per-image file so the data can be re-merged later
rugnux -o myrun -N 32 --write-process-h5 dataset_master.h5

# also write an unmerged MTZ, to scale the data with aimless instead
rugnux -o myrun -N 32 --export-unmerged dataset_master.h5

# check the merged data against a known structure: R-work / R-free and maps
rugnux -o myrun -N 32 --model model.pdb dataset_master.h5
```

Re-merging is cheap and does not re-read the images. Ask the full run to keep its per-image file
with `--write-process-h5`, and `--mode scale` will then re-scale and re-merge the reflections
already integrated in it — seconds rather than minutes:

```
rugnux -o myrun -N 32 --write-process-h5 dataset_master.h5   # integrate and merge once
rugnux --mode scale -o remerged -A myrun_process.h5          # re-merge, here anomalously
```

Use it to try a different resolution limit, anomalous setting, outlier rejection or reference MTZ
without paying for integration again. `--mode scale` merges in the space group and cell the file
records, so the second command needs no `-S`. Note that `--no-merge` also writes a `_process.h5`,
but a run that never merged never determined a space group either, so re-merging that file lands in
P1 unless you pass `-S` yourself — `--write-process-h5` is the one to use.

### Rotation data

Index, integrate, scale and merge a rotation sweep, fully de novo:

```
rugnux rotation_master.h5 \
    -o rotation_run -N 32 \
    --scaling-high-resolution 1.4
```

Because the dataset carries a rotation goniometer axis, it is processed as **rotation data by
default**: two-pass rotation indexing (index the sweep once, then process every frame against that
lattice) with the **`rot3d`** partiality model (rotation partials combined into 3D fulls). Scaling
and merging run **by default** (for both rotation and stills; `--no-merge` turns them off); the unit
cell is taken from the rotation indexer and the space group is determined from systematic absences,
and both are written
into the merged `.cif`.

Run **fully de novo** (no `-C`/`-S`) for the best result — supplying a cell or space group up front
tends to *degrade* low-symmetry cases. A `-S` group whose Bravais lattice the crystal turns out not to
have stops the run and names the cell that was indexed, rather than merging in a frame the reflections
are not in; where the lattice does have that group's setting, the reflections are reindexed into it. `--scaling-high-resolution` (set it to your expected
resolution) sharpens both the space-group search and the error model. To tune the first pass use
`--two-pass-rotation=100` (or `-R100` — the first-pass image count); to force the sweep to be
treated as independent stills use `--force-still`.

By default a rotation run also **post-refines the geometry** in a second pass: the first pass
integrates and merges at the header geometry, then the detector distance + beam centre and the crystal
cell / rotation-axis are refined against the merged fulls (cross-validated, and committed only for a
small < 1 % move, with the gauge-weak beam centre restrained toward the header), and the second pass
re-indexes de novo and re-integrates at the refined geometry. The refined pass is the canonical
`<prefix>_*` output; the header-geometry pass merges only to choose the space group and to judge the
refined pass against, and writes no merged files of its own — no `<prefix>_01.mtz`, `.cif`, `.hkl` or
`_01_image.dat`. (Where a process file is asked for at all, with `--no-merge` or
`--write-process-h5`, each pass still writes its own, so `<prefix>_01_process.h5` appears beside
`<prefix>_process.h5`.) Disable it with `--rotation-no-postrefine`.

After the per-frame scale-fulls step, rotation scaling applies three **correction surfaces**, **on by
default** (`--no-scaling-corrections` disables all):

- **Decay** — a global Debye–Waller relative-*B* over the run, for the radiation damage that weakens
  later frames more at high resolution (a resolution×time systematic the resolution-flat per-frame
  scale cannot remove). It only engages when the total relative-*B* exceeds a physical floor (2 Ų). An
  optional `--relative-b[=deg]` extends this single global rate to a smooth per-batch relative-*B* curve
  (default 10°-of-rotation batches when bare, off otherwise), cross-validated like the surfaces here, for
  crystals whose decay is non-linear in dose.
- **Absorption** — a smooth multiplicative factor over the diffracted-beam direction in the goniometer
  frame (path length through the crystal). Negligible at hard X-rays / thin crystals; it matters at
  low photon energy. Its benefit shows up most on model-based metrics: a smooth absorption error
  largely cancels among symmetry mates (little effect on the error model / ISa) but still biases the
  intensities, so it measurably lowers *R*<sub>free</sub>.
- **Modulation** — a smooth multiplicative factor over the position where a reflection lands on the
  detector (a flat-field: detector-response and geometric systematics that vary across the detector
  plane). Symmetry-equivalents of one reflection land at different detector positions as the crystal
  rotates, which over-determines the surface. Because it lives in the detector frame (not the
  rotation) the same correction concept applies to stills. This is the largest of the three on
  JUNGFRAU data — it lowers *R*<sub>meas</sub> by several to tens of percent on datasets that carry a
  detector systematic, while holding or improving CC<sub>1/2</sub> and the anomalous signal.

All three are **cross-validated** — fitted on even-numbered frames and kept only if they improve the
held-out odd-frame symmetry-equivalent agreement by a clear margin (and vice versa). The agreement is
scored as a σ-independent, *R*<sub>meas</sub>-like fractional deviation, so a surface can never pass
cross-validation by merely reshaping the sigmas; where the systematic is absent the surface is a no-op
rather than a source of added noise, which is why they are safe to leave on.

Independently of any correction, a rotation run prints a **radiation-damage report** — the per-image
scale correlation-to-merge and mosaicity versus dose, and the relative *B*-factor change over the run
(first→last) together with a per-batch relative-*B* curve, also written to the merged mmCIF. It is a
data-quality-vs-dose diagnostic and never alters the merged intensities. A batch whose data cannot
support a measurement prints `-` instead of a value, and the first→last number is printed only where a
straight line describes the curve — damage is progressive, so a curve that dips and recovers is a
disturbance of the sweep, not dose, and the report says so and points at the sweep-quality section
(`RADIATION_DAMAGE_RELATIVE_B= NOT_A_TREND`).

### Still / serial data

A dataset with **no goniometer axis** (e.g. a serial grid scan) is processed as **independent
stills automatically** — no flag needed. Known-cell indexing with the GPU fast-feedback indexer,
then merge against a reference structure:

```
rugnux serial_master.h5 \
    -o serial_run -N 32 \
    -X ffbidx -C 79,79,38,90,90,90 -S 96 \
    -z reference.mtz \
    --scaling-high-resolution 1.8
```

`ffbidx` requires a known cell (`-C`) and is the indexer of choice for sparse serial stills. The
self-calibrating spot finder is on by default for both workflows (`--no-adaptive-spots` turns it off), and for
serial stills leave `--min-pix-per-spot` **unset** so it is chosen per image — across the still-target battery this
combination raises the indexing rate and typically extends resolution over a fixed threshold and
fixed min-pix, at equal or better CC½. (You can still pin a fixed threshold with `--spot-sigma` /
`--spot-threshold` and a fixed min-pix with `--min-pix-per-spot`.) If a dataset *does* carry a
goniometer axis but you want per-frame stills processing anyway, add `--force-still`.

## Command-line options

General:

| Option | Description |
| --- | --- |
| `-o, --output-prefix <txt>` | Output file prefix (default: `output`) |
| `-N, --threads <num>` | Number of worker threads (default, and for any value ≤ 0: all hardware threads). Some stages take fewer, because past a point more workers make them slower: the per-image loop of `--mode mx` uses at most 16 per GPU unless `-N` was given a positive value, and first-pass spot finding and the beam-stop pre-scan have ceilings of their own that `-N` does not lift. Scaling, merging and the space-group search use the full count |
| `-s, --start-image <num>` | First image to process (default: 0) |
| `-e, --end-image <num>` | Last image to process (default: all) |
| `-t, --stride <num>` | Process every *n*-th image (default: 1) |
| `-v, --verbose` | Verbose output |

Mode — `--mode <name>` (default `mx`):

| Value | Description |
| --- | --- |
| `mx` | Full analysis — spot finding, indexing, integration and merging |
| `azint` | Only azimuthal integration (no spot finding/indexing); writes `<prefix>_process.h5` |
| `scale` | Only re-scale/merge the already-integrated reflections in the input `_process.h5` (no re-integration) |
| `calibration` | Determine the detector geometry from powder rings; writes `<prefix>.poni` |

Calibration (`--mode calibration`):

| Option | Description |
| --- | --- |
| `--calibrant <name>` | Powder standard: `lab6` \| `agbh` \| `ceo2` \| `si` \| `ice` (default `lab6`, case-insensitive) |
| `--calibration <txt>` | How the rings are measured: `rings` \| `spots` (default `rings`; see above). `rings` defaults `--azim-phi-bins` to 32 |

Detector mask:

| Option | Description |
| --- | --- |
| `--detect-beam-stop[=N\|off]` | Find the beam stop and its holder in a projection of N images and add them to the pixel mask as bit 9, so nothing shadowed by them is integrated. **On by default** (60 images); `=off` disables. Reflections behind the stop are attenuated but not flagged, so they integrate low with a plausible sigma and no existing rejection catches them |

Geometry:

| Option | Description |
| --- | --- |
| `--estimate-beam-center` | Measure the direct beam before indexing, from the symmetry of the spots where the sweep reaches at least half a turn and from the radial background profile where it does not; the value in the file is kept where neither can measure it. Off by default |
| `--no-fit-spindle` | With the above, keep the rotation axis given in the file instead of fitting its skew about the beam |

Spot finding:

| Option | Description |
| --- | --- |
| `--spot-sigma <num>` | Noise sigma level for spot finding (default: 4.0) |
| `--spot-threshold <num>` | Photon-count threshold for spot finding (default: 10) |
| `--adaptive-spots` | Self-calibrating detection (**default**, stills and rotation alike): the strong-pixel threshold comes from each image's own per-resolution-ring noise instead of the fixed `--spot-threshold`, so one setting adapts across datasets (no per-dataset `--spot-threshold`/`--spot-sigma` tuning) |
| `--no-adaptive-spots` | Turn adaptive detection off and use the fixed `--spot-threshold` / `--spot-sigma` finder |
| `--spot-false-pixels <num>` | Adaptive-detection operating point: expected noise pixels tolerated per frame (default: 100; implies `--adaptive-spots`) |
| `--spot-high-resolution <num>` | High-resolution limit for spot finding, Å. Omitted (or 0): no resolution clipping — spot finding extends as far as the detector reaches, for rotation data as well as stills |
| `--spot-low-resolution <num>` | Low-resolution limit for spot finding, Å (default: 50; lower it, e.g. 24, to exclude the direct-beam halo on weak serial data; 0 removes the limit) |
| `--min-pix-per-spot <num>` | Minimum connected strong pixels per spot. **If omitted, min-pix is chosen per image** (stills indexing): the frame is indexed at min-pix 3/2/1 and the one maximising indexed-spot count × indexed fraction is kept. Give an explicit value to force a fixed min-pix instead. |
| `--max-spots <num>` | Maximum spots kept per image (the strongest ones) and handed to indexing (default: 1000) |
| `--detect-ice-rings[=on\|off]` | Flag ice-ring spots (de-prioritised in indexing) and exclude ice-ring reflections from scaling. Default: the master file's `detect_ice_rings`, or — where the file carries no such key — **on for rotation and off for stills** |

Azimuthal integration (the radial profile behind the per-image ice-ring score):

| Option | Description |
| --- | --- |
| `-q, --azim-q-spacing <num>` | Q bin spacing, 1/Å (default: 0.01; finer resolves the narrow ice rings) |
| `--azim-min-q <num>` | Minimum Q, 1/Å |
| `--azim-max-q <num>` | Maximum Q, 1/Å. Omitted: integration extends to the highest Q the detector reaches. The adaptive spot finder shares these Q bins, so this also sets how far self-calibrating detection can see |
| `--azim-phi-bins <num>` | Number of azimuthal (phi) bins (default: 1) |
| `--polarization-correction <on\|off>` | Enable/disable the azimuthal polarization correction |
| `--solid-angle-correction <on\|off>` | Enable/disable the azimuthal solid-angle correction |

Indexing:

A dataset with a **rotation goniometer axis** is processed as rotation data (two-pass rotation
indexing) by default; a dataset without one is processed as independent stills. `--force-still`
overrides the former; the `-R` / `--single-pass-rotation` / `--force-rotation-lattice` flags request
rotation explicitly and pick the pass or lattice.

| Option | Description |
| --- | --- |
| `--force-still` | Treat a rotation (goniometer) dataset as independent stills instead of rotation |
| `-X, --indexing-algorithm <txt>` | `FFBIDX` \| `FFT` \| `FFTW` \| `Auto` \| `None` |
| `-C, --unit-cell <cell>` | Reference unit cell `"a,b,c,alpha,beta,gamma"` (required by `ffbidx`) |
| `-S, --space-group <num\|symbol>` | Space group number (`92`) or Hermann-Mauguin symbol (`P43212`) — for indexing and scaling |
| `-r, --refine <txt>` | Geometry refinement: `none` \| `orientation` \| `beam_and_lattice` (default) \| `flex` (try all three per image, keep whichever indexes the most spots; alias `multi`) |
| `-R, --two-pass-rotation[=num]` | Two-pass offline rotation indexing (default for goniometer data; optional first-pass image count, default 100) |
| `--single-pass-rotation[=num]` | Online-like single-pass rotation indexing (optional min angular range, deg) |
| `--force-rotation-lattice <vec>` | Force rotation lattice (9 floats, Å), skipping the first pass |
| `--rotation-no-postrefine` | Rotation: disable the default-on two-pass geometry post-refine (see the rotation section) |
| `--refine-geometry[=N\|off]` | Stills: extra first pass that bundle-adjusts the shared beam/distance/cell from N strongly-indexed frames (default 200) then re-indexes; default ON for stills with a reference cell (`-C` / `-z`), `=off` disables |
| `--index-ice-rings[=on\|off]` | Index on the spots flagged as sitting on an ice ring too, instead of setting them aside (default: **off**; no effect without `--detect-ice-rings`, which does the flagging) |

Indexer choice in brief: `ffbidx` (GPU) refines toward a **known cell** and is best for sparse
serial stills; `fft` (GPU) / `fftw` (CPU) index **de novo** and suit strong rotation data. See the
[CPU/GPU data-analysis reference](CPU_DATA_ANALYSIS.md) for the algorithms.

Scaling and merging:

| Option | Description |
| --- | --- |
| `--no-merge` | Skip scaling and merging (on by default); write only the per-image `_process.h5` |
| `-A, --anomalous` | Anomalous mode (keep Friedel pairs separate) |
| `--scale-fulls` / `--no-scale-fulls` | rot3d: refit a per-frame scale on the combined fulls (XDS order, Unity model); on by default for rotation data, off for stills |
| `--smooth-g[=deg]` | rot3d: smooth the per-frame scale *G* over a degree range before the 3D combine (XDS DELPHI-like; default 5° for rotation, 0 = off) |
| `--no-scaling-corrections` | rot3d: disable the default-on decay + absorption + modulation correction surfaces fitted on the fulls after scale-fulls (see below) |
| `--relative-b[=deg]` | rot3d: fit a per-batch relative-*B* beyond the single decay slope over deg-degree batches, cross-validated (default 10° when bare; off otherwise) |
| `--simple-stills` | Stills: treat every reflection as a full (*p* = 1, single-pass scale/merge) — disables the default-on physical partiality post-refinement |
| `--no-expected-variance-merge` | Stills: disable the default expected-variance merge weighting (which rebuilds each weak observation's signal variance at the reflection mean to de-bias the inverse-variance merge); restores observed-sigma weighting |
| `--capture-uncertainty <num>` | rot3d: systematic sigma on under-captured fulls, ~num·(1−captured_fraction)·I (default: 1.0 for rotation, 0 otherwise) |
| `--min-captured-fraction <num>` | rot3d: drop a combined full whose rocking curve was captured below this fraction — edge-of-sweep truncated fulls (default: 0.7 for rotation, 0 otherwise; 0 = off) |
| `--scaling-high-resolution <num>` | High-resolution limit for scaling, Å — manual override (default: no limit; disables the automatic cutoff below) |
| `--scaling-low-resolution <num>` | Low-resolution limit for scaling and merging, Å (default: 50, the value XDS configurations use; 0 removes the limit). Reflections coarser than this sit behind or beside the beam stop and are measured on a background it has eaten into |
| `--resolution-cutoff <txt>` | Automatic high-resolution cutoff for the written reflections and reported shells: `cc-logistic` \| `off` (default: `cc-logistic`; ignored when `--scaling-high-resolution` is set) |
| `--resolution-cc-target <num>` | CC1/2 target defining the `cc-logistic` fall-off (default: 0.30) |
| `--resolution-shells <num>` | Number of resolution shells in the reported statistics table (default: 10) |
| `--min-partiality <num>` | Minimum partiality to accept a reflection (default: 0.02) |
| `--ice-min-score <num>` | Ice-presence gate: the measured per-run ice score (1 = no ice) a dataset must reach before **any** ice handling is applied — the flagging and the exclusion from scaling (default: 1.5; 0 = no gate). The eleven fixed hexagonal bands cover 16–26 % of the unique reflections whether or not the crystal has ice, so handling ice on a clean crystal only costs completeness |
| `--ice-min-spot-ratio <num>` | The second ice-presence channel: found **spots** on the hexagonal rings over the same q width of ice-free flanks beside them (1 = spots spread evenly). Ice in large crystallites diffracts as discrete spots and leaves the radial profile flat, so `--ice-min-score` alone is blind to it (default: 2.0; 0 disables this channel) |
| `--reject-outliers <num>` | Per-observation outlier rejection, N σ from the per-reflection median (default: 6 for `rot3d`, off otherwise) |
| `--min-image-cc <num>` | Per-image CC limit, percent (default: no limit) |
| `--search-min-zeta <num>` | De-novo space-group search only: also search a merge of just the observations whose Lorentz geometry \|ζ\| reaches this, and report both answers (default: 0.85 for rotation, 0 = single search). Reflections crossing the Ewald sphere near-tangentially are measured worst and can make a real symmetry operator look like a twin law. Where the two searches disagree, the merge of all the observations decides — as it always has for the systematic absences |
| `--mosaicity <num>` | Diagnostic: fix the scaling mosaicity (°) instead of using the per-image seed |
| `--scaling-iterations <num>` | Scaling iterations with no reference data (default: 3) |
| `-z, --reference-mtz <file>` | Reference MTZ (enables reference-driven scaling) |
| `--reference-column <label>` | Reference MTZ column to use (default: auto — F-model, else IMEAN/I/…) |
| `--model <file.pdb>` | After merging, validate the merged intensities against this atomic model (see below) |
| `--write-process-h5` | Also write the (large) `_process.h5` when merging (default: only `.mtz`/`.cif`) |
| `--export-unmerged` | Also write the integrated observations as `<prefix>_unmerged.mtz`, an unmerged MTZ (POINTLESS column layout) for aimless / pointless / careless. Rotation partials are summed into one full per reflection. Intensities carry the Lorentz-polarization factor and nothing else — the partiality is not divided out and the per-image scale is not applied. Works in `--mode mx` and `--mode scale`. See [The unmerged export](#the-unmerged-export) |
| `--export-unmerged-partials` | As above, but writes `<prefix>_unmerged_partials.mtz` with each partial as its own row (one batch per image) for the reading program to sum |

Integration:

| Option | Description |
| --- | --- |
| `--integrator <txt>` | Spot integrator: `gaussian` (profile-fit, default) \| `empirical` \| `boxsum` (classical fallback) |
| `--integration-radius <r>` | Signal-box radius `r1`, or `r1,r2,r3` (px). One value ⇒ `r2=r1+2`, `r3=r1+4` |
| `--adaptive-integration-radius[=on\|off]` | Set the signal radius `r1` from how wide this crystal's spots actually are (default: **on** for rotation, off for stills). `r1` is not the integration domain — that is the profile-fit grid — but it *is* the aperture the profile **width** is learned over, and a second moment over a disk of radius `a` saturates at `a²/4`, so at the shipped `r1 = 4` the learned σ can never exceed 2 px and a broader spot is fitted with a profile the model cannot represent. The pre-scan reads `r80`, the radius holding 80 % of a spot's flux, off isolated strong spots over a fixed 14 px aperture that owes nothing to `r1`, fits it against `1/d` and evaluates it at 5 Å; then `r1 = clamp(round(2·r80), 4, 6)`, `r2 = r1 + 2`, and `r3` is taken so the `r2..r3` background ring keeps the area it has at the default `4,6,13`. The ceiling of 6 is pattern density: `r2` also drives the neighbour-ownership radius and the ring's inner edge, and past it a dense pattern starts losing reflections whose ring falls below six clean pixels. Ignored when `--integration-radius` is given. The widened radius applies to the **final** integration pass only — the two-pass geometry pre-pass keeps the radius the run started with, because the post-refinement fits the detector distance and beam to the observed reflection positions and those move with the signal disk (33 µm and 0.02 px between `r1 = 4` and `r1 = 6` on one crystal, enough for the second pass's de-novo lattice search to settle on a different lattice and index a fifth fewer frames). And where the widened radius leaves more than 1.1 % of the predicted reflections without a background ring — a pattern too dense for it — the final pass is re-integrated at the fixed 4 px radius, and the log says so. Over the rotation regression battery it moves 12 of 38 crystals and leaves the merged intensities of the other 26 unchanged; where it moves them, per-shell ⟨I/σ⟩ improves by up to 31 % and R_meas by up to 24 % |
| `--integration-stencil <k>` | Push the `r2..r3` background ring out by `k` times the beam's radial streak `bandwidth·R_px`, per reflection (default `0` = the fixed circular ring). A fixed ring otherwise ends up on a streaked reflection's own tails at high resolution and measures them as background. Only the ring moves, and only radially — the `r1` signal box stays a circle — and the growth is capped at `2·r3`. The neighbour exclusion grows with it, so on a crowded pattern a few reflections can be left with too little background and dropped. Needs `--bandwidth`: on a monochromatic beam the streak is zero and this does nothing |
| `--background-clip <n>` | Monochromatic (rotation + still): high-side clip of the background ring at `mean + n·√mean` (default 4; 0 = off). The default background estimator — it rejects neighbour cores and zingers without the symmetric trim's Poisson skew bias. Broadband data always clip, at 3σ; ignored by `--integrator boxsum` |
| `--background-trim <f>` | Use the old symmetric trimmed mean for the background ring instead of the clip, 0≤f<0.5 (`0.10` was the former default). Switches `--background-clip` off. A symmetric trim is biased low on Poisson data and adds ~5 counts to every partial, so this is for back compatibility only; `0` = plain ring mean. Rings holding more than 512 pixels fall back to the plain mean (the GPU sorts the ring in shared memory and the CPU now matches it), which the default radii never reach but wide ones do |
| `--background-radial[=on\|off\|auto]` | Correct the background ring for the **curvature** of the radial background (default **off**). Disk and ring are concentric, so a background linear in position cancels between them and only curvature survives — which on a smooth ice ring reaches +26 counts on a single reflection. `auto` applies it per image where that image's ice score shows a *smooth* powder ring, since the model is a function of radius alone: on ice made of discrete crystallite spots there is no smooth ring and the correction makes the bias worse. Ignored by `--integrator boxsum` (no clip pass to take the curve from) |
| `--integration-high-resolution <num>` | High-resolution limit for prediction and integration. Omitted (or 0) means integration extends as far as the detector reaches — which is what the predictor can place on the detector anyway, since it rejects reflections that miss it. Set a value to integrate less than the detector offers |
| `--max-hkl <n>` | Predict reflections with \|h\|,\|k\|,\|l\| ≤ `n` (max 511). By default this is derived per crystal from the refined cell as `ceil(max(a,b,c)/d_min) + 1`, which is the exact bound: the predictor keeps only \|q\| ≤ 1/d_min and `h = a·q`, so no reflection can lie outside it and no candidate inside it is wasted on a shorter axis. Set it only to override that |
| `--bandwidth <num>` | Relative X-ray bandwidth FWHM (e.g. `0.01` for a 1% DMM); default from file or 0 (monochromatic) |
| `--overlap <txt>` | What to do where two predicted reflections share signal pixels: `off` \| `reject` \| `exclude` (default `exclude`). A shared pixel belongs to the nearer centre; without this a crowded reflection reads high on a dense pattern. `exclude` drops the shared pixels from the profile fit, which renormalises itself, and keeps the reflection; `reject` instead drops the whole reflection when too little of its profile is cleanly its own. `--integrator boxsum` has no profile to renormalise, so only `reject` acts there |
| `--overlap-minpk <f>` | Least fraction of a reflection's expected profile that must be usable for it to be kept (default 0.75, XDS `MINPK`). Governs both the fraction that must be **readable** — not masked, untrusted, in a gap or overloaded — in every profile mode, and, under `--overlap reject`, the fraction that must be cleanly its own. Under `--integrator boxsum` any unreadable pixel discards the disk outright and the reject fraction goes by disk *area*, which cuts harder |
| `--prediction-mosaicity <num>` | Diagnostic: fix the rocking width (deg) the **prediction** window opens to, leaving partiality on the per-image σ_M. The two are one number by default, so a σ_M that moves takes the integrated reflection population with it |

Geometry overrides (defaults are taken from the input file; override them to reprocess with a corrected geometry):

| Option | Description |
| --- | --- |
| `--beam-x <num>` | Beam centre X (pixel) |
| `--beam-y <num>` | Beam centre Y (pixel) |
| `--detector-distance <num>` | Detector distance (mm) |
| `--wavelength <num>` | Wavelength (Å) |
| `--rot1 <num>` | PONI detector rotation 1 (rad) |
| `--rot2 <num>` | PONI detector rotation 2 (rad) |
| `--polarization <num>` | Polarization factor |
| `--rotation-scale <k>` | Goniometer rotation scale: the stage turned `k` times the angle stored in the file (the commanded one). Applied to both passes, and overrides the scale rugnux fits for itself |