leonarski_fandClaude Opus 5.5
f849e2d1be
The two pre-scan steps that were still CPU-bound in a GPU build now run where the projection already is. - FindBeamCenterFromBackground: the per-iteration binning pass and the two clip rounds run on the device (BeamCenterBackgroundGPU); the fit itself stays on the host. Each cell is summed in the host's order (pixel order within the host's row blocks, blocks in order), and the per-pixel cell/derivative formula is shared (BackgroundBand.h). The angles come from BackgroundAtan2 (IEEE ops only) instead of atan2f, and both translation units are compiled without FMA contraction, so host and device give the same bits: 0 of 6.5 M pixels in a different cell, identical walks on the three in-house rotation sets. With glibc/CUDA atan2f and default contraction ~30 pixels per 16 Mpx sweep changed cell and the fitted centre moved by up to 0.05 px. - ShadowFinder::GetMask: the whole mask (pooling, ring medians, components, morphology, hole fill, arm search) runs on the device from ShadowAccumulatorGPU's projection (ShadowMaskGPU), so the 360 MB projection no longer comes back; the mean projection is divided on the device too (same bits). The two small fits over rings and sectors (BlockedOutTo, HarmonicFit) are shared with the host path in ShadowFinderInternal.h. Integers, comparisons, sorts and components are exact; the polarization trig, the Poisson log and the arm-search azimuth are not, so a pixel at a threshold can differ. The one-time change against the previous CPU arithmetic (BackgroundAtan2, no contraction), measured on the myoglobin, cytochrome C and thaumatin rotation sets: ring centre moves 0.002-0.045 px (fit sigma 0.75-1.2 px), beam-centre capture 0.01-0.04 px; beam-stop mask differs on 31 / 144 / 53 pixels of 259k / 144k / 198k (25 of the myoglobin ones are GPU-vs-CPU arithmetic in the mask, the rest follow the centre); hot-pixel mask identical. Spot width, integration radii, bandwidth, beam-centre arbitration, indexing, space group, cell, resolution and the merged statistics table are identical; only the error model moves in its 4th digit. CPU build: the same centres and decisions. Timing (GPU, box at load 30-38): ring walk 0.54 -> 0.23-0.27 s, mask 1.24-1.44 -> 0.18-0.22 s, beam-centre capture walk 1.1-1.3 -> 0.31-0.35 s. Tests: ShadowFinder_DeviceMaskMatchesHost, BeamCenterFromBackground_DeviceMatchesHost (bit-exact), plus [ShadowFinder], [BeamCenter], [HotPixelFinder]. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01K5K8jvPPbmCrbqnWkddTuB
41 lines
2.0 KiB
C++
41 lines
2.0 KiB
C++
// SPDX-FileCopyrightText: 2026 Filip Leonarski, Paul Scherrer Institute <filip.leonarski@psi.ch>
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// SPDX-License-Identifier: GPL-3.0-only
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#pragma once
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// Included only under JFJOCH_USE_CUDA. Free of CUDA headers, so the host fit can hold one.
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#include <cstdint>
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#include <memory>
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#include <vector>
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#include "BackgroundBand.h"
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// The two passes over the pixels of the background beam-centre fit (FindBeamCenterFromBackground),
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// on the device: binning every usable pixel into its cell about a trial centre, and summing the
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// binned pixels again under a clip. They are all of the fit's cost; the fit itself stays on the host.
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//
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// Each cell is summed in the order the host sums it - pixel order within each of the host's row
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// blocks, the blocks then added in block order - so a pixel that lands in the same cell on both
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// sides adds the same rounding on both. Whatever differs comes from BackgroundBandCell (see there).
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class BeamCenterBackgroundGPU {
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struct Impl;
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std::unique_ptr<Impl> impl;
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public:
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// block_row: the first row of each of the host's row blocks, and one past the last row at the end.
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BeamCenterBackgroundGPU(int width, int height, const std::vector<int> &block_row,
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const char *usable, const float *mean);
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~BeamCenterBackgroundGPU();
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// Bin the band about (beam_x, beam_y) and sum each cell: the values, their squares, the two
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// derivatives, and the count.
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void Bin(const BackgroundBand &band, float beam_x, float beam_y,
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std::vector<double> &sum, std::vector<double> &sum_sq,
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std::vector<double> &sum_jx, std::vector<double> &sum_jy, std::vector<int32_t> &count);
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// Sum the pixels the last Bin put in each cell again, leaving out those above the cell's
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// clip_limit and every pixel of a cell whose limit is negative.
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void Clip(const std::vector<float> &clip_limit,
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std::vector<double> &sum, std::vector<double> &sum_sq, std::vector<int32_t> &count);
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};
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