HDRI backround rendering problem...

Hello again, Al, Rich,

I have found the strangest problem relating to the HDRI background. My animation starts by looking out at the sunset, then zooms back into the bathroom, dabbles around and finally ends by zooming out the bathroom window again. Here are those key frames, and a few in-between, In animation order... What is important to note is the size / intensity of the sun.

Opening frame big sun::

Zooming all the way back... (sun is still large, still Scene 0 - first scene)

Next frame which goes into Scene 1 (second Scene)... Sun is small and not so intense...

Now the kicker...

Next-to-last-frame. You can see window sill on the sides, still has a small sun:

And finally the last frame, and the sun goes large / brighter again:

I can reproduce this behavior without doing an animation. It seems to depend on how much of my real model is shown. If I backup the camera about 1 inch and show a bit of the modem (window frame), I will get a small or "normal" sun. If I go back only about 1/2 inch, it will show the big/brighter sun again.

Got any idea what might be happening here? And how I can work around it?

regards,

-randall

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Permalink Reply by Rich Hart on September 5, 2012 at 9:06pm

Just guessing here, but since the HDRi is a light source, I assume it is getting brighter when there are no visible lights in the room anymore to balance out the lighting, like the way your pupils enlarge when you turn the lights in the room off. Unfortunately the rendering eye doesn't adjust to the change in lighting as slowly as your pupils do.

Perhaps you could use a Spherical or Cylindrical background, that wouldn't be a light source, to represent the sunset.

I'd have to play around with it to see if that would work at all in an animation, though.

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Permalink Reply by Randy S on September 6, 2012 at 11:26pm

Hi Rich,

Since I have reported a number of things that relate to this model, I will upload it so you are free to investigate things further if you like.

What's odd about this particular issue is that the lighting of a scene is always "locked" to the Scene you are going to. eg If I am rendering Scene 4 to Scene5, the lighting will take on however they are set for Scene5. So this situation is unique in that it changes mid scene (albeit the very last frame of the scene). But I'm sure if I changed the scene, so it goes out the window earlier (earlier then the last frame) we'd see the same behaviour.

regards,

-randall