Help: Color in tree populations randomly "popping" out

[masonspappy]

I'm animating a camera to move closer to a cabin. When I reach a particular frame the leaf color on a tree behind the cabin suddenly "pops" or brightens considerably. (See frame with red circle). In the next frame the leaf color is back to normal.  I can't figure out why it's doing this and been trying to solve it for a few days. If anyone has any ideas where to look I'd really appreciate hearing from you. Thanks!

[Dune]

Strange. I can only imagine things happening to leaf color if variation is linked to a distance shader attached to the render camera (which would not be a wise thing to do, and is probably not the case), or reflection is changed by changing of the frustrum (suddenly reflecting detail that isn't inside the 'scope' of the frustrum, so to say). But that may be too far fetched as well. And I don't use the built in color variation method, so I don't know if that could cause it.
I believe there was an issue like changing leaf color in another thread a few weeks ago, but cannot find it right now.

[cyphyr]

Very odd indeed.

Did you pre-calculate the GI_Cache?

It doesn't look like a GFI_Cache problem although it may be related.
I usually write every 10th frame and then Blend mode "Interpolate (for animation)"> Number of files to blend> 5 (this is the default). However this sometimes is not sufficient and you may need to write a more frequent number of frames and/or blend a higher number of GI_Cache files.

Also check the tree leaf shader. Does it have any non-standard values in it? Especially in the specular and translucency channels. Check if the effect is repeated if everything is set to 0 (except defuse).

Good luck and do let us know what the solution turns out to be.

[sboerner]

If you place a new (not animated) camera at the precise position as the animated camera at that particular frame, using the same focal length, do you get the same result? With motion blur enabled/disabled? With/without GI cache?

Aside from the camera, is anything else in the scene animated?

Just looking for a way to simplify the problem and eliminate a few things.

[masonspappy]

Thanks guys - really appreciate the feedback.  I did try disabling the population but now I get the dreaded error message "... Terragen has stopped working...". and it continues to fail even after re-enabling the population.  I've deleted and reinstalled TG4 (I'm currently running V4.1.25 - 2 levels back, I think) and still getting the "stopped working" message.  I've loaded the previous save level of the TGD file  and it's rendering now - seems like it's running ok. So it looks like something in the TGD file, not Terragen itself.  Assuing this render runs ok, I'm going to reload the failing version and re-try a few of the suggestion you all made. Will let you know, and again, really appreciate the feedback!

[masonspappy]

Well, got the animation rendering again which is a good thing....

But now the original problem - the "color pop" (see picture below) is back.   I'm not using a PF for shading. And the color isn't in the next frame. And it's not in the exact same position as before. Seems like it's moved up just a bit.

[WAS]

Wondering if this is a lighting problem. I've been doing some planets lately and needing to up enviro light a lot to do like glows from the surface, and all over the planet I'll get circular lighting in the enviro, areas lit brighter just like what's shown here.

The same thing is visible in my Brown Dwarf rings with enviro light upped to get light from the planets self luminance.

Check out this original resolution image of the brown dwarf image

Mind you all, I've played with enviro light for years and haven't seen this more uniform soft glowball effect before outside light sources and GISD. I wonder if the frame effects are bringing out this issue, as it seems light-albedo based.

[Matt]

Check your Image Map Shaders and Default Shaders to see if any of them have "Unpremultiply" checked. If so, turn that off. If your textures aren't created in the right way to be used with the unpremultiply option, it can create extremely bright samples which can lead the issue you see in your render.

v4.3 includes a change to make this option safer to use on textures that weren't designed for it, so it isn't much of a problem in v4.3 and newer.

A GI cache file sequence might not fix the problem, and it will spread it out over a few frames if it occurs in one of the cache files.

[masonspappy]

Check your Image Map Shaders and Default Shaders to see if any of them have "Unpremultiply" checked.

That's interesting. I do have them checked.  Let's see what happens when I uncheck them.
Thanks Matt!!

[masonspappy]

Check your Image Map Shaders and Default Shaders to see if any of them have "Unpremultiply" checked.

That's interesting. I do have them checked.  Let's see what happens when I uncheck them.
Thanks Matt!!

Bingo! That fixed it Matt!  Just rendered all 40 frames and no problem at all.  Thanks Matt, and all you guys for your help.

[Dune]

Great! I have to remember that as well, as in some older objects the default shader still has it checked.