I have a simple scene with FinalGathering and 1 raytraced light that contains a few very low resolution spruce trees. The scene renders in about 1:30 without alpha for the leaves, but as soon as I apply the alpha texture, the render time shoots up to almost 4 min. I’ve tried MIA material x and a simple blinn, thinking the MIA material would be faster, it wasn’t. Am I missing something completely?
Alpha channel substantially increases render time (MentalRay)
Panupat
#2
Same issue with V-ray and Arnold. These engines just can’t handle alpha channel that well. It’s better to model your leaf than cutting it with alpha. Arnold in particular eats geometry for breakfast so you can really go crazy.
Cutout Opacity in the mia_mat_x shaders works just fine, at least prior to Maya 2016. Since you can’t do actual cutout opacity with the Blinn or other native shaders, it’s not a direct comparison but in all my tests the mia_mat_x was faster anyway, barring blurred reflections perhaps. Are you using instancing or references, perhaps? Sure, cutout opacity takes a little more juice but compare it to a geometry-only scene and you’ll get about the same results, since it’s still doing tons of calcs. We’ve gone over this topic for years. Here’s a scene with several billion polys, mostly cutout opacity leaves, which rendered very quickly:
