Dark Frame in Bongo/VRay Render Sequence

Not sure if this belongs in the rendering section, may be a VRay issue rather than Bongo.

I’m a new Bongo user, just working on my first simple animation. I’ve rendered two sequences so far (both in VfR); first 150 frames and the second 300. They’re exactly the same animation, I just needed the sequence to be longer hence the 300 frames.

In both sequences, I have one frame that is rendered much darker than all others - under exposed. In the first sequence of 150, it was frame 81; in the second of 300, frame 164 was dark. I can’t find any reason for this - can anybody point me in the right direction?

Thanks in advance for any help.


Can you give more information about what you are trying to render, could you also upload the visopt settings you are using.

Does the camera move – and go behind the light? If so, make the light invisible so it won’t block the camera.

Also, please post two frames for comparison; one normal and one ‘too dark.’

EDIT / UPDATE: I jut did a test, thinking that you may have accidentally animated the light’s power / intensity. It doesn’t look like that parameter CAN be animated, so I tried another one: light size. I found that you can animate a light’s scale, which would definitely cause the light to change brightness during an animation.

Check that setting. A easy place to look as the Bongo → Animation Manager. Everything animated will show up there.

Thanks for your reply, Matt.

I’m using the render preset >General>Low. Physical camera with a shutter speed of 30.

Thanks for replying, Dave.

Yes, the camera follows a path around a target. The camera passes in front of the light, I’ve taken a screen grab of the set up.

And here is a comparison of the frames in question - it is just frame 164 that is dark.

I can’t show the whole image but hopefully you can see the issue. I have checked the Animation Manger but can’t find any reference to the light size being animated.

Thanks again for your help.

Did the camera exposure / f-stop / ISO speed get animated? Check for any listing of the camera in the Animation Manager as well. Something is changing!

What happens when you render the three frames as separate stills? (vs. a sequence)

There can also be occasional glitches & bugs that you never figure out. If I find that I’m spending 30 minutes trouble-shooting – and I can delete and re-build in 15 minutes – then I will punt and try a fresh set-up.That should also include saving with a new name, closing, and re-opening Rhino. That actually helps a lot of V-Ray issues.

I haven’t intentionally animated anything but the camera path and target path - following the example in your Lynda course (it’s a good introduction, by-the-way. More Bongo courses would be great :slight_smile:). I’ve double checked the animation manager but there is no mention of any camera setting.

The frames in my previous response are individual renders straight from vRay. They render exactly the same as when I do a sequence.

When I have a bit more time I’ll strip out the commercial stuff from the file and post it here. It could just be a glitch, the workaround in this case it to adjust the errant frame in Photoshop.