Does removing scene objects not visible in the view being rendered improve performance?

jamesramirez6734

I usually removing as much as I can from a scene whenever I render a specific shot (in order to boost rendering performance), which can actually take a while in some complex cases.

I just wanted confirmation this is actually worth doing? Is there nothing built into Daz which makes it automatically exclude any object not visible in the shot?

I expect not as that non-visible object might still be expected to affect the lighting in some way?

RobotHeadArt

Correct. Removing objects will help reduce memory usage and speed renders up.  There is no automatic culling as you deduced because objects out of scene could glow or reflect light or cast shadows into the viewable scene.

jamesramirez6734

Great - thank you!

The Blurst of Times

Another way to do it would be to use an Iray Section Plane Node (Create -> New Iray Section Plane Node).

Everything ABOVE the surface of that plane gets "cut" from the render calculations. So you just position & rotate that plane so that it slices off what isn't in the view of the camera. (It might change cast shadows and lighting if light sources are cut out by the Section Plane node, although you can tweak your node for the lighting.)

The point is to reduce the calculations for the renderer. It will try to simulate all of the little photons in your scene, even if they are off-camera, so limiting photon bounce/reflection (I think it's automatically infinite path length (as limited by reflectivity of your surfaces)? (Render Settings->Optimization->Max Path Length of -1 = infinite, as I recall. In a room with highly reflective surfaces, changing this number can help a bunch) and limiting the amount of stuff to calculate the photon bounces will make the renderer go faster.

marble

The Blurst of Times said:

Another way to do it would be to use an Iray Section Plane Node (Create -> New Iray Section Plane Node).

Everything ABOVE the surface of that plane gets "cut" from the render calculations. So you just position & rotate that plane so that it slices off what isn't in the view of the camera. (It might change cast shadows and lighting if light sources are cut out by the Section Plane node, although you can tweak your node for the lighting.)

The point is to reduce the calculations for the renderer. It will try to simulate all of the little photons in your scene, even if they are off-camera, so limiting photon bounce/reflection (I think it's automatically infinite path length (as limited by reflectivity of your surfaces)? (Render Settings->Optimization->Max Path Length of -1 = infinite, as I recall. In a room with highly reflective surfaces, changing this number can help a bunch) and limiting the amount of stuff to calculate the photon bounces will make the renderer go faster.

For the same reason I often use the Section Plane to allow light into a room from the HDRi dome by placing it inside a wall or ceiling. 

ed3D

~  And also how about Hidden _ would this have simiular result ??  thanx 

marble

ed3D said:

~  And also how about Hidden _ would this have simiular result ??  thanx 

I've seen conflicting views on this so I don't know. I know that the geometry is still loaded into VRAM but it is the large format textures that take up most VRAM and I think that they are loaded whether or not they are visible. Whether hiding them improves render times is, to me, unsure.

alliance4g63

marble said:

ed3D said:

~  And also how about Hidden _ would this have simiular result ??  thanx 

I've seen conflicting views on this so I don't know. I know that the geometry is still loaded into VRAM but it is the large format textures that take up most VRAM and I think that they are loaded whether or not they are visible. Whether hiding them improves render times is, to me, unsure.

 

Your take is interesting and I was going to start a thread asking a question about this. I have 8g VRAM and it was a struggle to include more than 2 G8 characters and a decent environment in one scene. Scene Optimzer has helped a ton. However, SO revealed things I had hidden still showed in the SO calculations.

So I have concluded that when you hide something in the scene it is still included in the VRAM calculation. I have resorted to deleting or hiding via SO only. Can anyone else confirm?

RobotHeadArt

Iray Section Planes do not avoid the memory usage of objects. Even though they are not visible in the render they and all of their textures are still loaded into the GPU memory for rendering.  You can verify this by looking in the log and seeing the number of textures and size of geometry loaded.

FirstBastion

Completely removing what is not seen in a scene (not in camera view) will save on memory and save on calculation time,  thus speeding up render times. Add the steps of saving the trimmed down scene,  Shutting down DS,  then reloading the scene with a fresh start and cleared cache.