Different CPU_GPU calculation

Rendering V-Ray
1

I ran the same render (without caustics and other effects, identical settings) on both CPU and GPU.
In GPU rendering it is as if a level, a layer, is missing, in fact, when opening the file with Photoshop you notice the lack. Furthermore, the refraction effect is less evident, the translucent material is less transparent, with a different color.

On the contrary, the CPU calculation is perfect, free from defects, but it is very slow.
Is this a bug or a GPU code compilation flaw?

CPU

Calcolo CPU perfetto
Calcolo CPU perfetto1400Ă—788 2.07 MB

GPU
Calcolo GPU RTX impreciso
Calcolo GPU RTX impreciso1400Ă—788 1.65 MB

Is it a file saving problem? (except in png).

2

I just realized that the image rendered in CPU and then saved also has a defect (in the green bottle on the right). I opened the file in Photoshop and a layer is missing. Help me!

3

There are always some differences between CPU and GPU rendering. Both engines are different.

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4

I like the GPU orange juice. Per CPU it looks like carrots juice. :slight_smile:

Best make a setup in your favorite mode and don’t switch. It’s not the same code, it’s different software.

5

The CPU orange juice reminds me of that really intense “blood orange” (not quite, but some variations perhaps) you can find in some shops, and is served along the Mediterranean coast in various restaurants.

What caught my eye is the blue caustic/colour pickup of the glass through the CPU calculation. Though mamy renderers do a really great job of it; it is a demonstration that just slamming everything through the GPU may not always be correct. The CPU render depth is far more impressive to me.

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6

I confirm! The CPU calculation is more precise, the refractions perform better. The problem lies in its slowness: without an RTX it is almost impossible to work fluidly with Vray, even worse with other render engines.