Texture projection problem

[Sbowling]

There is so much "noise" in the scene I can't really tell what your problem is. Can you create a simplified version of the problem? The only thing I can really make out in the picture is the buildings on the left.

[N_wEvil]

Sorry, I thought i'd hilighted the problem with the red circles (down the right hand leg of the robot)

I'll make up a short animated GIF when later on today when I get home, but for now let me try to explain;

I'm mapping a renderer output back onto the scene geometry with a camera projection to get a fast motion blur pass.

Since it is a camera projection the textures should not be slipping off the geometry as the camera movement hasn't changed, neither should the objects all be slipping in different directions.

The green skyscraper on the left seems to creep up, and texture on the robot seems to swim every which way.

Oddly enough, the render region gives me a perfect result and the UV editor doesn't suggest that there are any problems updating the UV's, hence my conclusion that somehow XSI isn't sending mental ray the correct UV data.

[N_wEvil]

Does this help any?
(apologies for the size)

http://www.andymelville.net/documents/textureprob.gif

[Sbowling]

Sorry, I thought i'd hilighted the problem with the red circles (down the right hand leg of the robot)


I saw the red circles, but I just wasn't sure what I was supposed to be lookihng at inthem, since everythign is basically a bunch of littel squares and circles. The animated Gif helps a lot with the buildfing, but I'm not seeing the problem on the robot arm.


I'm mapping a renderer output back onto the scene geometry with a camera projection to get a fast motion blur pass.

Since it is a camera projection the textures should not be slipping off the geometry as the camera movement hasn't changed, neither should the objects all be slipping in different directions.

The green skyscraper on the left seems to creep up, and texture on the robot seems to swim every which way.

Oddly enough, the render region gives me a perfect result and the UV editor doesn't suggest that there are any problems updating the UV's, hence my conclusion that somehow XSI isn't sending mental ray the correct UV data.

The first hings that come to mind is that the texture projection for the building is being projected from a different camera than the one being used to render animation.

As for the texture on the robot, I would make sure the uv projections are frozen, so that they can't move. I would also make sure you don't have and animation applied to any of the textures on either of the problem objects.

Finally, I'm not sure why you don't just render out the background as a seperate pass and comp it in later.

Looking at this again, it almost looks like the building is moving with the robot. I wonder if you may have somehow got the uvs backwards, so that the robot textures are moving with the camera and the building textures are moving with the robot. I know htis is a long shot, and probably not even possible, but I thought I'm throw it out there just in case....

[N_wEvil]

The thing is, everything is the one camera projection so even if there was a mismatch between the standard pass and the motion blur pass, surely the objects would be mismatching in the same direction?

Freezing the UV's isn't an option as it's a sequence of images mapped onto a camera projection, hence I need the UVs to update every frame.

As for not rendering the background out, I did try but as this is a personal project and I had no deadline to hit I felt that having some moving reflections in the BG helped make it look a little more alive.

I have tried seperating everything out for this pass but even if I cut the robot out and render it using this technique I still get the mismatch, so it doesn't appear to be a problem with simply having too many objects at once. Very frustrating :-/

Thanks for responding :)

[mocaw]

Is it as simple as you having your textures in sequences? Building1.psd, Building 2.psd, Building 3.psd, etc. etc. and that for each frame and that these DON'T match your camera?

That is the only way I can explain the shift.

I think something VERY simple like that is going wrong in all honesty.

If you wanted reflections then why not do that as a separate pass?

[N_wEvil]

mocaw-

Yes that is is exactly. A still image sequence mapped back onto the geometry with a camera projection. Very simple and seemingly not much to go wrong.

However the UV editor displays everything as it should be, but i'm not getting the correct result from the renderer output, which is what is making my head hurt.


As for doing a reflection pass - either way I would still need to motion blur and I felt I wouldn't be getting much out of splitting it up that way other than another sequence of images. The scene is just a diffuse pass and an AO pass comped together right now.

Thanks for taking the time to reply :)

[Felipe]

It seems that the texture support is moving with some part of the leg. Are you sure the texture support has no relation (child, contrains) with the moving parts of the robot?

[N_wEvil]

Hi Felipe,

Not to my knowledge. AFAIK a camera projection is constrained only to the camera and it's movements match exactly to the desired result. The camera itself has no constraints to the robot model, and the buildings in the background are also independent of the robot model. Also the viewport and render region output the correct result, it's only using the output renderer that there seems to be a problem. I could understand and fix the problem if it was consistent across the UV editor, the viewport, the render region AND the output renderer, but it's just the final output that seems to give me a screwy result.

If I drag out a render region and play the animation forward a few times it's still correct, however if I leave XSI to render some sequential frames I get an incorrect result within 3-5 frames. The problem manifests if I use render-->current pass OR batch rendering.

As I said above, the UV editor seems to think everything is fine so somehow, the right UVs aren't getting to the renderer o_O

Thanks!

[Sbowling]

If I drag out a render region and play the animation forward a few times it's still correct, however if I leave XSI to render some sequential frames I get an incorrect result within 3-5 frames. The problem manifests if I use render-->current pass OR batch rendering.


So if you draw a region and do a capture of the animation, everything is fine? If so, I would suspect that your render settings are not set up the same as your preview/region settings.

[N_wEvil]

Sbowling-

Both render settings are exactly the same - i've checked it multiple times.

Thanks for the suggestion :)

[N_wEvil]

Well, I did find a workaround in the end.

Exporting the whole sene to an mi2 archive then rendering in the command line with ray3.exe seemed to solve it, works fine now.

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