Tree leaves disappearing during view port render

[timAugustine]

Hi all,

I'm hit with a peculiar problem! Have you seen something like this before?

I'm rendering two tree (around 4M faces each) and while the view port render is going on, the leaves start to fade and then disappear. This only happens to one of them at a time. Both the trees have the same materials.

This is how the tree looks like when there are no issues:

solid leaves

This is how it starts to fade:

fading leaves

I wonder if it's because I'm very close to using up my computer's resources:

task manager

The leaf material is a simple PBR. Thank you so much in advance for any response!

Regards
Tim

[linograndiotoy]

Hard to tell what the issue may be without taking a look at the scene.

[Lewis]

Have you started rendering trees in the summer and then ended up in Fall ?

If yes then then it could be considered as feature that leaves fall off automatically ?

[timAugustine]

LOL @Lewis!

It's such a puzzling issue. I'm still facing it but right now I'm focusing on other parts of the scene so it's not an active issue. I'm not sure how to share this scene as it's a 1 GB+ file. I've ditched the second model of the tree and have been using instances of only one tree in the whole scene and I'm still facing this issue.

I'm going to try a few more things later on like experimenting with removing the translucency of the leaves to see if it has anything to do with this!

Tim

[Whispermode]

LOL @Lewis!

It's such a puzzling issue. I'm still facing it but right now I'm focusing on other parts of the scene so it's not an active issue. I'm not sure how to share this scene as it's a 1 GB+ file. I've ditched the second model of the tree and have been using instances of only one tree in the whole scene and I'm still facing this issue.

I'm going to try a few more things later on like experimenting with removing the translucency of the leaves to see if it has anything to do with this!

Tim

I've had this before and can't remember for the life of me what it was - not helpful, sorry, but maybe have a look at the normals on the leaves and the gamma values on the alpha.

Also, the denoiser can do weird things over time - I've had it gradually removing shadows before, so worth a look.

[timAugustine]

This issue was on the back burner for a while and now I would really like to fix it. Please note that this tree I'm rendering is quite heavy on my system (rtx1070 mobile version) and the tree has 10 million polygons and I've "instanced copied" the leaves to have foliage cover on the tree.

I'm adding a video of this happening for reference. Any help troubleshooting this is much appreciated!

I should also note that this video was recorded during the final render and not view port render

[linograndiotoy]

It would be great if you could share a simplified scene still showing the issue, so we can take a deeper look.

[frankmci]

I'm adding a video of this happening for reference. Any help troubleshooting this is much appreciated!

It will be a lot easier to offer suggestions if you tell us what trouble shooting you have already done. The most obvious thing is to first try it with a much simpler version of the same scene setup, eliminating as many variables as possible.

[timAugustine]

So far, this is what I've noted:

It does not disappear if it has nothing intersecting with it. If add the tree trunk, the leaves start to disappear. If it's just the leaves, they render fine.
I'll try to duplicate the .blend file and start simplifying it and the upload it here. Thanks!

[frankmci]

So far, this is what I've noted:

It does not disappear if it has nothing intersecting with it. If add the tree trunk, the leaves start to disappear. If it's just the leaves, they render fine.
I'll try to duplicate the .blend file and start simplifying it and the upload it here. Thanks!

I'd try greatly simplifying the trees themselves, too. Use a couple of scrawny saplings with only a few leaves. Try it with simple color materials applied to all geometry instead of any bitmap textures. Start from a clean, new scene file to eliminate any oddities or extraneous elements that may have crept in during project development. If you can repeat the behavior in such a simple scene, it should be relatively easy to track down what's causing the issue.