As the title says (same as redshift). The reason is, I’m currently unable to have scenes which contain more than 700mb of compressed textures. A limit which doesnt apply to most of the other GPU engines I’ve used.
I love blender by the way, it’s incredible the amount of thought that’s gone into the workflow! Brilliant.
excerpt from redshift page:
Redshift can successfully render scenes containing gigabytes of texture data. It can achieve that by ‘recycling’ the texture cache (in this case 128MB). It will also upload only parts of the texture that are needed instead of the entire texture. So when textures are far away, a lower resolution version of the texture will be used (these are called “MIP maps”) and only specific tiles of that MIP map.
Because of this method of recycling memory, you will very likely see the PCIe-transferred figure grow larger than the texture cache size .
Once reserved memory and rays have been subtracted from free memory, the remaining is split between the geometry (polygons) and the texture cache (textures). The “Percentage” parameter tells the renderer the percentage of free memory that it can use for texturing.
Say we are using a 2GB videocard and what’s left after reserved buffers and rays is 1.7GB. The default 15% for the texture cache means that we can use up to 15% of that 1.7GB, i.e. approx 255MB. If on the other hand, we are using a videocard with 1GB and after reserved buffers and rays we are left with 700MB, the texture cache can be up to 105MB (15% of 700MB).
Once we know how many MB maximum we can use for the texture cache, we can further limit the number using the “Maximum Texture Cache Size” option. This is useful for videocards with a lot of free memory. For example, say you are using a 6GB Quadro and, after reserved buffers and rays you have 5.7GB free. 15% of that is 855MB. There are extremely few scenes that will ever need such a large texture cache! If we didn’t have the “Maximum Texture Cache Size” option you would have to be constantly modifying the “Percentage” option depending on the videocard you are using.