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# px

## PURPOSE

'px': transform fields from physical coordinates (phys) to image (px) coordinates

## SYNOPSIS

function [DataOut,DataOut_1]=px(Data,CalibData,Data_1,CalibData_1)%DataIn,Calib)

## DESCRIPTION

    'px': transform fields from physical coordinates (phys) to image (px) coordinates

## CROSS-REFERENCE INFORMATION

This function calls:

- px_XYZ 'px_XYZ': transform phys coordinates to image coordinates (px)

This function is called by:

- geometry_calib 'geometry_calib': performs geometric calibration from a set of reference points
- probe_calib 'probe_calib': performs geometric calibration from a set of reference points

## SUBFUNCTIONS

- function DataOut=px_1(Data,Calib)

## SOURCE CODE

    0001 %'px': transform fields from physical coordinates (phys) to image (px) coordinates
    0002
    0003 % OUTPUT:
    0004 % DataOut:   structure of modified data (transforms DataIn)
    0005 %       DataOut.CoordType='px': labels image coordinates
    0006 %       DataOut.CoordUnit= 'px' : units of output coordinates
    0007 %       DataOut.X and .Y arrays of image coordinates X, Y
    0008 %       DataOut.U, .V velocity in pixel displacement on the image (unit=px), if velocity exists as input
    0009 %
    0010 %INPUT:
    0011 % DataIn:  structure of possible input data (like UvData) or cell of structures (several fields):
    0012 %      DataIn.CoordType='phys': allows transform to px, else no transform   (DataOut=DataIn)
    0013 %      DataIn.X and .Y arrays of physical coordinates X, Y
    0014 %      DataIn.Z corresponding array of Z coordinates (=0 by default)
    0015 %      DataIn.U, V corresponding array of velocity components
    0016 %      DataIn.W corresponding array of the third velocity component in 3D case
    0017 %      DataIn.dt: time interval of the image pair used for velocity measurement (NEEDED TO GET OUTPUT RESULT))
    0018 %      DataIn.A, AX, AY : image or scalar input -> EMPTY  CORRESPONDING OUTPUT (A REVOIR)
    0019 %      Other fields in DataIn: copied to DataOut without modification
    0020 % Calib: structure containing the calibration parameters (Tsai) or containing a subtree Calib.GeometryCalib with these parameters
    0021 %
    0022 % call the functions phys_XYZ or px_XYZ (case of images) for pointwise coordinate transforms
    0023
    0024 function [DataOut,DataOut_1]=px(Data,CalibData,Data_1,CalibData_1)%DataIn,Calib)
    0025 % A FAIRE: 1- verifier si DataIn est une 'field structure'(.ListVarName'):
    0026 % chercher ListVarAttribute, for each field (cell of variables):
    0027 %   .CoordType: 'phys' or 'px'   (default==px, no transform)
    0028 %   .scale_factor: =dt (to transform displacement into velocity) default=1
    0029 %   .covariance: 'scalar', 'coord', 'D_i': covariant (like velocity), 'D^i': contravariant (like gradient), 'D^jD_i' (like strain tensor)
    0030 %   (default='coord' if .Role='coord_x,_y...,
    0031 %            'D_i' if '.Role='vector_x,...',
    0032 %              'scalar', else (thenno change except scale factor)
    0033 if  ~(exist('CalibData','var') && isfield(CalibData,'GeometryCalib'))
    0034     DataOut=Data;
    0035 else
    0036     DataOut=px_1(Data,CalibData.GeometryCalib);
    0037 end
    0038 if exist('Data_1','var')
    0039     if ~(exist('CalibData_1','var') && isfield(CalibData_1,'GeometryCalib'))
    0040         DataOut_1=Data_1;
    0041     else
    0042         DataOut_1=px_1(Data_1,CalibData_1.GeometryCalib);
    0043     end
    0044 else
    0045     DataOut_1=[];
    0046 end
    0047
    0048
    0049 %------------------------------------------------
    0050 function DataOut=px_1(Data,Calib)
    0051 DataOut=Data;%default
    0052
    0053 %Act only if .CoordType=phys, and Calib defined
    0054 if isfield(Data,'CoordType')& isequal(Data.CoordType,'phys')& ~isempty(Calib)
    0055     DataOut.CoordType='px'; %put flag for pixel coordinates
    0056     DataOut.CoordUnit='px';
    0057     %transform of X,Y coordinates
    0058     if isfield(Data,'Z')&~isempty(Data.Z)
    0059         Z=Data.Z;
    0060     else
    0061         Z=0;
    0062     end
    0063     if isfield(Data,'X') & isfield(Data,'Y')
    0064         [DataOut.X,DataOut.Y]=px_XYZ(Calib,Data.X,Data.Y,Z);
    0065         if isfield(Data,'U')&isfield(Data,'V')& isfield(Data,'dt')& ~isequal(Data.dt,0)
    0066             Data.U=Data.U*Data.dt;
    0067             Data.V=Data.V*Data.dt;
    0068             if isfield(Data,'W')
    0069                 W=Data.W*Data.dt;
    0070             else
    0071                 W=0;
    0072             end
    0073             [XOut_1,YOut_1]=px_XYZ(Calib,Data.X-Data.U/2,Data.Y-Data.V/2,Z-W/2);
    0074             [XOut_2,YOut_2]=px_XYZ(Calib,Data.X+Data.U/2,Data.Y+Data.V/2,Z+W/2);
    0075             DataOut.U=XOut_2-XOut_1;
    0076             DataOut.V=YOut_2-YOut_1;
    0077         end
    0078     end
    0079     %transform of an image
    0080     if isfield(Data,'A')&isfield(Data,'AX')&~isempty(Data.AX) & isfield(Data,'AY')&...
    0081                                    isfield(Data,'AY')&~isempty(Data.AY)&length(Data.A)>1
    0082 %         if isfield(Data,'Field')&isequal(Data.Field,'images')
    0083           %NO TRANSFORM FROM phys to px for images
    0084             DataOut.A=[];%
    0085     end
    0086 end
    0087