- Added a local maximum search for 2D detectors in support of peak

search for TRICS
2001-11-02 15:31:49 +00:00
parent 3c916c9a7d
commit 6c5db4ffd0
10 changed files with 892 additions and 30 deletions
--- a/lomax.w
+++ b/lomax.w
@ -0,0 +1,104 @@
+\subsection{Local Maximum Search}
+This module implements searching for local maxima in a 2D histogram of 
+data. It is mainly intended for use at TRICS where initially
+reflections need to be searched for the determination of a UB
+matrix. The local maximum algorithm is a little more sophisticated
+then commonly used in that the window of the search is user definable,
+and a valid maximum has to have a certain steepness against the
+bordering points in order to be valid. Another validity test is a
+threshold which must be reached. All these enhancements should reduce
+the number of false maxima which may turn up as the result of horrible
+measurement statistics. 
+
+The position and intensity of a local maximum found can be refined further
+ with a center of gravity calculation within a given window including all
+ data points above a certain threshold expressed as a fraction of the local
+ maximums intensity.
+
+Again this module has a little data structure:
+ 
+@d lomaxdata @{
+	typedef struct __LOMAX {
+				  pObjectDescriptor pDes;
+	                          ObPar *pParam;
+				}LoMax;		          
+@}
+The fields are:
+\begin{description}
+\item[pDes] The standard object descriptor.
+\item[pParam] The parameters of this object.
+\end{description}
+
+The exported interface is simple: just the necessary functions for
+representing the object in the interpreter and a function which allows
+to use the local maxima search from another module. If the latter is
+ever needed.
+
+@d lomaxint @{
+  int LoMaxAction(SConnection *pCon, SicsInterp *pSics,
+		  void *pData, int argc, char *argv[]);
+
+  int LoMaxFactory(SConnection *pCon, SicsInterp *pSics,
+		  void *pData, int argc, char *argv[]);
+
+  int testLocalMaximum(int *iData, int xsize, int ysize,
+                      int i, int j, 
+                      int window, int threshold, int steepness,
+                      int *intensity);
+  int calculateCOG(int *iData, int xsize, int ysize,
+	          int *i, int *j, int *intensity,
+                  int cogWindow, 
+                  float contour);
+                  
+@} 
+
+testLocalMaxima checks if point i, j is a valid local maximum. It
+returns true (1) if this is the case, or false (0) if this is not the
+case. The window parameter describes how much points shall be searched
+in each direction. 
+
+calculateCOG calculates the center of gravity for point i, j,. Points within a
+ sqaure window of size cogWindow are considered. Only points whose
+ intensity obeys I \gt I(i,j)*countour are used for the COG
+calculation. The position of the maximum (i,j) and its intensity are
+updated by calculateCOG.
+
+  
+@o lomax.h @{
+/*-------------------------------------------------------------------------
+                   L o c a l     M a x i m u m
+
+ This is a module for searching a local maximum in a 2D histogram as
+ collected at TRICS.
+
+ copyright: see copyright.h
+
+ Mark Koennecke, November 2001
+-------------------------------------------------------------------------*/
+#ifndef LOCALMAXIMUM
+#define LOCALMAXIMUM
+#include "obpar.h"
+
+  typedef struct  __LOMAX *pLoMax;
+
+@<lomaxint@>
+
+
+#endif
+@}  
+
+@o lomax.i @{
+/*-------------------------------------------------------------------------
+                   L o c a l     M a x i m u m
+
+ This is a module for searching a local maximum in a 2D histogram as
+ collected at TRICS. These are internal definitions only and are
+ supposed to be included only into lomax.c
+
+ copyright: see copyright.h
+
+ Mark Koennecke, November 2001
+-------------------------------------------------------------------------*/
+@<lomaxdata@>
+
+@}