I roughly sketched out the hills and wadi in GIMP and saved as a greyscale .png, loaded that into Wilbur to do various terrain processing things, exported it as an 8 bit .bmp height map file, loaded that back into GIMP, flipped it vertically (for some reason SB1 maps are flipped on the N-S axis) adjusted the levels to get the elevations roughly where they need to be, saved that as a raw file and then used a hex editor to add the width and height to to beginning of the file, renamed the file extention to .hgt, put it on the maps folder where the old style maps are stored (not the new 4.1 style maps,) and then used the import .hgt function in the map editor.