The help for RTV_DOIT discuss how the in_memory array should be set up (yes, an array which is a little unusual!): IN_MEMORY Set this keyword to an array of ones and zeros indicating the storage location for each of the output vectors. IN_MEMORY is a long-integer array of ones and zeros with the same number of elements as VALUES and OUT_NAME. So in some example code that I have using ENVI's sample dataset, I set it up like this: envi_open_file, 'C:\Program Files\Exelis\ENVI50\classic\data\bhdemsub.img', r_fid=fid envi_file_query, fid, dims=dims pos = [0] values = [1250, 1300, 1350, 1400, 1450, 1500] out_names = 'testimg_' + $ strcompress(string(values),/remove_all) + '.evf' l_name = ['1219', '1288', '1357', '1426', '1494', '1563'] in_memory = lonarr(n_elements(values)) envi_doit, 'rtv_doit', fid=fid, pos=pos, dims=dims, $ values=values, l_name=l_name, in_memory=in_memory, $ out_names=out_names

Hi Mari, Adding in the "in_memory = lonarr(n_elements(values))" line helped greatly and allowed the program to run after a bit more debugging on my end. My ultimate goal with this is to create contour maps - when I use the RTV_ENVI doit on heightmap rasters, I get an error "The following raster values were not contained in the input band so no vector values was created:" with a varying list of contour levels. The resulting vectors that only encircle a few pixels in random places throughout the image - is there a better way to get contours on an ENVI raster, or am I doing this right?