Texture Size / Dimension? Render speeds.

mmoch25

What would slow down a render more, 2MB textues at 4096 x 4096, or a 5MB textures at 1024 x 1024

Is it the size or dimension?

I tend to reduce my textures down in size, but occasionally the smaller sizes use up more memory. So I wandered is it better to use the original larger textures.

hphoenix

Texture sizes will only slow down a render if it is in Iray and causes it to drop to CPU due to the scene being too big to fit in the GPU memory.  The smaller textures will typically take up less memory....as they'll be converted to raw format then compressed internally inside the GPU, so the dimensions are usually the bigger concern.

 

mmoch25

Ok, thanks for that.

 

Maraun

The size for textures is width x height x channels x bits per channel.

For example:

4096 x 4096 x 3(RGB) x 8(0-255) = 402653184 bits / 8 / 1024 / 1024 = 48 MB.
1024 x 1024 x 3(RGB) x 8(0-255) = 25165824 bits / 8 / 1024 / 1024 = 3 MB.
4096 x 2048 x 3(RGB) x 32(HDR) = 805306368 bits  / 8 / 1024 / 1024 = 96 MB.

The file has compression but this don't matter for render engine.