The Grid Catchment Calculations form is used to carry out calculations based on all pixels that lie upstream of any other pixel.
The calculations that are performed on each pixel in the 'Source Grid' are controlled by the selection in the 'Operation' drop down box. A summary of each of the available operations is provided below:
•Min Value: Extracts the minimum pixel value from all upstream pixels
•Max Value: Extracts the maximum pixel value from all upstream pixels
•Average of Values: Extracts the average value of all upstream pixels
•Similarity (Number of Matches): Number of upstream pixels with the same pixel value
•Similarity % (Proportion of Matches): Number of upstream pixels with the same pixel value divided by the total number of upstream pixels
•Connectivity (Number of Connected Matches): Number of upstream pixels with the same value that are directly connected (i.e., not separated by a pixel with a different value)
•Connectivity % (Proportion of Connected Matches): Number of upstream pixels with the same value that are directly connected divided by the total number of upstream pixels
•Decay: This is currently not implemented
