Hi,<br><br>I have a collection of MODIS imagery files (in Erdas Imagine .img format), and I need to to be able to derive new files from them, where the derived file has the same format and metadata as the input files, but each pixel in the derived file file is some arithmetic function of the corresponding pixels in the input files. For example,<br>
<br> derived_file_pixel(i,j) = average of pixel(i,j) for each input file<br><br>I'd like to set up a system for creating these derived files that makes it easy to change the particular function (for example, compute the sum instead of the average, or compute a difference, or a weighted average, etc etc), and easy to change the set of input files.<br>
<br>I poked around in the GDAL documentation and it looks like one way to do this would be to use a VRT with a pixel function, but it looks like that would involve writing a program, either in C or in python. I can do that, but ultimately I'd like to set things up so that my<br>
non-programmer colleagues can change the pixel function and generate new derived files without having to get me to write a new program.<br><br>So, I'm wondering if there's a command-line utility program that can be used for doing this kind of thing, that allows the pixel function to be given as parameter on the command. Either a program that's part of GDAL itself, or part of some other package that uses GDAL? I'd appreciate any suggestions.<br>
<br>Also, if I do end up writing the program myself using GDAL, does the VRT + pixel function approach I described sound like the best way? I know enough about GDAL to feel pretty sure that it'd be good for doing this kind of thing, but I've never actually written a program using GDAL, so I'd appreciate any pointers.<br>
<br>Thanks!<br><br>--Mark<br><br>