Render effect motion blur with cards

[Seraph135]

I'm doing a animation which has some weeds growing next to some buildings. I've mapped them onto cards and I'm using the render effect motion blur because I can't afford the rendertimes of 3d motion blur AND I have a mixed pipeline with Brazil/scanline. So I have to use image blur on this one to keep everything consistant.

The problem is that the cards render very dark with "work with transparency" checked, but they look ok without it checked.

I don't think I'll have a problem on this project with not using the transparency since the camera doesn't come too close to them, but I'd like to have someone else confirm that this is a bug. Or explain why its happening. It doesn't happen with scanline.

Thanks!

Tim J

[jacksc02]

could you show some images? it will help to figure this out

[Seraph135]

I would have but I'm currently at work and not able to upload images from here. I can do it tonight....However,

It should be very simple to re-produce. Create a card object and a camera move. Render with render effect motion blur with and without the transparency check box checked and compare the results. I had this problem even in a brand new file.

version 1.47.03

The version with transparency checked is significantly darker than the version without.

Tim J

[Morbid Angel]

i would strongly suggest to stay away from max's image motion blur for number of reasons, one of the being that it can produce unresolvable flickering.
Instead I would suggest rendering to rpf with motion blur velocity and then do an rpf motion blur in post. Works well, fast, no problem .

[Seraph135]

Ok here is an example. This scene has only the card plant and a camera...No lights except the default lighting (Doesn't matter if lights exist in the scene or not). Any card object I create does this...not just this one.

Can someone please confirm that this is not just happening to me? or better yet explain why its happening?

Thanks,

Tim J

[Seraph135]

i would strongly suggest to stay away from max's image motion blur for number of reasons, one of the being that it can produce unresolvable flickering.
Instead I would suggest rendering to rpf with motion blur velocity and then do an rpf motion blur in post. Works well, fast, no problem .

Flickering is actually an issue I've never had with image blur, though I'm not suprized with all the other issues image blur presents. I have seen many horrible artifacts like diagonal lines cutting through the image and I won't even get started on what happens to particle systems.

RPF velocity motion blur is actually not an option for this project. Our tests with it have not gone well in the past.

I know there are a bunch of work arounds to resolve the problem, but I'd like to know why its happening in the first place.

Tim J

[vlado]

Tim, I've seen this effect, but I tend to get that with the scanline renderer too; I'll post images a bit later.

Best regards,
Vlado

[vlado]

Here are two scanline renderings:

no motion blur effect:


motion blur render effect with transparency option, still scanline rendering:


I think this is a problem of the motion blur render effect.

Best regards,
Vlado