The purpose of this file is to calculate the transformation from the local camera coordinates (pixels) to the physical world coordinates in your experiment. Currently only linear mapping is supported. The calling sequence for defining the mapping would then look like:
The world coordinates may be represented either by distinguishable dots or by a regular grid. For the former case one should specify an o for the typeofcoordinate input, whilst for the latter one should specify a + sign. If your image is called WorldCo1.bmp and contains a regular grid the calling should look like
>> definewoco('WorldCo1.bmp','+').This will make a window pop up containing the image. The mouse pointer will change to a circle, and the left mouse button is used to mark the points in the image that mark the World Coordinate system. After you have marked all your points you will be asked to type in the physical coordinates of each of the points marked with the mouse. These coordinates should be on the form [x y], with x being the horizontal and y being the vertical coordinate. Figure 2.2 shows the example image supplied with MatPIV. It can be relatively difficult to spot all the points present in the image, The figure shows the points that should be used in your mapping marked out with white circles. This figure also includes the physical coordinates to some of the points as used in that experiment. All numbers are measured in cm.