Is an image map that's called up in a default shader called once or twice (in color and and opacity, e.g.)? I mean, does it add twice the MB's into memory or once? Meaning; would it be better to take an image map shader and link that to the inputs of those if you need to keep a file lower in memory? Or a setup without the default shader but just the image map shader even?
The image is loaded twice. If you use a 4-channel image file with RGB for diffuse and the alpha channel for opacity, there's no way to save memory by using a separate Image Map Shader plugged into the 'function' input, because you'd still need two Image Map Shaders so that one can be set to "use alpha channel".
However, if you make your diffuse map a 3-channel image and then use a single-channel 8-bit image for your opacity, you can save memory. You might as well do this with the Default Shader though.
Matt
Thanks Matt.