The issue is the populator. My entire scene is almost complete with populations of vegetation. Now, I want to tweak some surface setting and make a cropped, test render to see how the tweaking works out. Each time I do this, the populator starts running again and eats up a lot of time. Is this normal?
Adjusting certain settings will cause the populator to repopulate and this is unavoidable. But do make sure that you have "recompute every frame" unchecked in your populations.
- Oshyan
Thanks Oshyan; I'll check that. One of the two populations on the scene takes quite awhile to populate. I guess I could disable the pops while tweaking other settings.
If you connect the last shader to the populations terrain input you may find that any change to the surfacing will result in a repopulation. You might be able to cut this down by connecting only the last node with any significant displacement (or the compute terrain node)... but I havent tested this. You can always cancel the populator and the render will continue with only the objects that have been "populated".
On a slightly related topic... if you use a distance shader to restrict the extent of a population from the camera, it pays to set the population size/position so that you have as little "empty" population as possible. The speed of the populator seems to be largely related to area, so a large area of a population with no objects in it will add a substantial amount to the render time. The other situation people commonly use is a through camera image map. In this case there's no point placing the camera in the centre of a population as everything behind the camera won't be visible but will be calculated. This is a particular performance consideration for animations, where it pays to move the populations with the camera.
Thank you Ben. Sorry I haven't replied sooner; but, I am traveling and haven't had a chance to catch up. As soon as I get back, I will go into your response in depth and get back to you.