Render complexity: Opacity Map vs Diffuse Map

Scavenger

I was wondering...Does an Opacity Map add to the Render time/complexity? 

For example, a fishnet body suit... an opacity map that lets skin be seen thru the holes vs faking skin beneath the net on the diffuse map.

The Opacity map would be a perferable thing, but if it'd be a very complicated thing to render, faking it would be better, I think.

mjc1016

That depends entirely on the renderer and shader used.

Iray probably has less overhead in that area than most of the 3Delight shaders used in Studio.  But 3Delight doesn't necessarily HAVE to be 'costly'

Scavenger

I guess I don't understand that answer.

Where my brain was was thinking "hmm...this net has thousands of holes in it, and the renderer would have to acount for the light going into to each of those holes to the surface beneath it, vs a solid surface colored differently.

 

 

ZarconDeeGrissom

That is a far more interesting question, then you or may think, lol. Some things are incredibly light on the CPU, others need more math, and the different 'effects' add up. A simply map with black or white pixels, can be incredibly efficient compared to one with shades of gray, especially in 3delight even with the simplest of shaders.

3delight. I once tried to make a floor with a light beneath it, and I used an opacity map to set the areas of glass, with another map for the same areas of reflectivity strength for the glass windows. It took **** ages to render. I ditched the reflectivity map in favor of no glass-like reflection, and it got faster. Changed the opacity map to black/white (instead of gray scale), and it rendered almost as fast as if the thing was just a solid surface. That was not even using a heavy-handed shader like AoA or Omni, tho I suspect the maths involved with light translucancy vs reflectivity will have similar results with them.

Iray, well, I've yet to have time to try it.

(EDIT, I had no idea that was a bad word, lol. WOW!)

Panzer Dragoon

Yes opacity maps can impact render time. Depends on settings. Like if the object

is hair, and you allow it to cast and receive shadows it will increase the time in 3DL. You can disable that if you want. 

Scavenger

Hmm...I guess I'll forge ahead with the opacity maps and keep the other idea in my back pocket for when I'm done, if needed! Thanks!

mjc1016

UberSurface (omnifreaker) can actually be MUCH faster with opacity...because it does have the occlusion controls.  Occlusion is the time killer these days, as the improvements in 3Delight's raytracer have sped up the shadows considerably.  

Also, 3Delight CAN use alpha-mapped TRANSPARENCY, but none of the usual Studio shaders do it that way!  Alpha mapped transparency is much faster than the opacity maps.