I was doing some tests to see what the gains were for using RAT as textures or environment maps. I was surprised to see EXR was noticeably slower than RAT or JPG/HDR for textures.

https://cerebero.wordpress.com/2016/02/17/to-rat-or-not/ [cerebero.wordpress.com]

Does anyone have some insights, perhaps, as to why this is? I thought that Mantra internally converts any non-RATs into RAT, so if anything, I'd expect to see EXR and JPG/HDR to be more similar.

When I generate an EXR via JPG –> RAT –> EXR, the files are twice as big compared to JPG –> EXR. I tried the EXR renders using the alternate JPG –> EXR but the times got even worse for EXR after that!

The images make this project way too big to post; I'll see if I can find a place to host them (I've just attached renders), but if anyone has some ideas, I'd be interested to hear them!

Thanks!