Topic: Associating Output Raster to Input Data
I am using COSI-Corr in the context of glaciology and feature tracking.
I would like to know how the resulting rasters relate to the original input data. I have noticed that the results are smaller in size compared to the input images. When overlaying both input and output data, the output leaves a margin compared to the input (see example image: http://img337.imageshack.us/img337/9022 … sicorr.jpg). I believe this is due to the search window and the size of this margin is probably defined by the window size.
I would now need to know, how the pixel positions of the original image are represented by the result. In my example I used the frequency engine with an initial window size of 128x128 and a final size of 32x32. The XY step was 16 pixels. When I compare input and output I have a left margin of 127 px and a top margin of 128 px. However, when I calculated the correlation with the same setup and the same input images but without map information (non-referenced images), the resulting rasters were 1 px (16 original px) narrower. In this case the left margin was 143 px.
- How can I determine, which original pixels belong to each pixel in the result? In other words, is the magnitude of displacement calculated from exactly the 16x16 pixels 'underneath' the resulting pixel?
- How do the margins of 127 and 128 px come about?
- Why changes the output size when using georeferenced images?
Thanks a lot.