Do you ever use all 2GB of VRAM?

[colorlabs]

I'm thinking about trading my 460 2gb for a 470 1.2gb for the speed boost. I never use more than a gig of memory, but I'm hoping to doing some more complex scenes in the future.

Memory use seems to come from three places: geometry, textures, and render size. So I did some experiments.

Geometry:
10k triangles used 22 MB
1m triangles used 200 MB
4m triangles used 680 MB (and took FOREVER to load )

Textures:
1024x1024 - used 4MB
2048x2048 - used 16MB
8192x8192 - used 250MB

Grayscale Textures: (via floatimage)
1024x1024 - used 1MB
2048x2048 - used 4MB
8192x8192 - used 64MB

Render size::
100x100 - used 2MB
1024x1024 - used 21MB
2048x2048 - used 81MB
4096x4096 - used 320MB
8192x8192 - used 1280MB
HD 1280x720 - used 20MB
HD 1920x1080 - used 41MB

So really, to use all 1.2GB (1280MB) of a 470's VRAM, I could have HD 1080p renders of:

• 2m triangles (400MB) and 55 textures at 2k
• 2m triangles and 13 textures at 4k
• 4m triangles (680MB) and 35 textures at 2k
• 6m triangles and no textures

As I'm mostly using Octane for video, I think I'll be keeping the triangle count low anyway to speed up Octane loading/voxelising. And really, for video (1080p) I don't think I'll be needing more than 2k or 4k textures. Seems like the 2GB cards are more for making work for print media...

However I'm pretty new to 3d and would love anyone's feedback on this.

[GeoPappas]

I believe that the amount of VRAM used is also a function of the render size. So an image that is 800x600 will take a lot less VRAM memory than an image that is 4000x3000.

[colorlabs]

Thanks GeoPappas, I forgot about that. It actually makes a huge difference! I edited my original post.

[ROUBAL]

I confirm that the memory amount is really important when you render in high resolution, or use very detailed models.

In my current scene, I use few textures, but I model each object with maximum detail to allow a total freedom for the camera location. So, each object can be seen in close up, like in real life.

This leads to constant struggle to keep everything fitting in the memory ! With 1.5GB, it is very difficult, and it is the reason why I try to use as less images textures as possible. Procedurals are not always suitable, but don't eat memory !

[san]

I confirm that the memory amount is really important when you render in high resolution, or use very detailed models.

or both


Just a note though, graphics cards are fast-moving items, they get refreshed within 9-12 months cycle and prices are going down quickly. Not a good long-term investment unless used to their max immediately since the day you bought it. So if you only need 1GB framebuffer now, and would appreciate a speed boost for your current projects then yes 470 will serve you better than 460 for now. Especially with its price going downhill.

Just make sure that ~1GB is all you need for the projects you're doing in maybe 1-9 months to come, depending on how often you'd be willing to trade cards. Whether team Radiance will be able to optimize 460 for Octane in the coming weeks/months is also a factor for 460 owners...

[face]

You can also use tricks.
Maybe a level of detail system or multi resolution textures.
It´s all scene dependent.
With a high aperture you can use the LOD/MRT rather...
For hidden objects which will be visible only in reflections/refractions, you can use the LOD/MRT.
You can animate the LOD/MRT with a switch if you animate a scene.
You can hide Objects, which are irrelevant for the scene.

And so on...

face