Velocity pass from multiple xmesh

[pieforme]

Hello,

I am getting a strange error in the velocity pass while rendering multiple xmeshes.If I use a multichannel exr then the velocity channel seems to be empty. However if I just render one xmesh I get the correct velocity pass. When using the render elements velocity pass it works when I have multiple xmeshes or if I have a single one , Although its incorrect when I have multiple xmeshes in that things that are stationary also have velocity on them.

[paul]

Thank you for your report! Unfortunately I was unable to reproduce this problem, so I’ll need more information from you.

Here’s what I tried. I used 3ds Max 2012 with the Default Scanline Renderer and XMesh Loader 1.1.3. I saved a moving sphere and a stationary box. I created three XMesh Loaders in my scene: two loading the moving sphere, and one loading the stationary box. I added a Velocity render pass, and rendered to an EXR file. The Velocity pass appeared as expected in the Render Preview Window and in the EXR file’s Velocity channel.

I have a few questions for you:* What version of 3ds Max are you using?

• What renderer are you using? (and what renderer version, if applicable)
• What version of XMesh are you using?

It might also be helpful if you could please send us a scene file that reproduces the problem. You can send us files using our ticket system. You may need to ZIP the file to get it through to us.

[pieforme]

Hi Paul,

Its actually the same file you were helping me with before, its to big to send but you should have a version of it. I am having the issue with the combined xmeshes from the same file.

What version of 3ds Max are you using?
max 2012
What renderer are you using? (and what renderer version, if applicable)
Mental Ray

What version of XMesh are you using?

The verision you sent me . I can have a look when i go in tomorrow.

Zoubein

[paul]

Thanks! I loaded the scene you sent me before.

I made two changes to fix the velocity pass:

1. Add a modifier (any modifier) to each XMesh Loader. I used a XForm modifier with no transform. (This workaround is required so that mental ray can recognize that the XMesh Loader is animated.)
2. Change the Loading Mode to “Frame Velocity Offset” in each XMesh Loader. (This will fix any “non-consistent topology” errors you may have seen in mental ray.)

Could you please try making these same changes in your scene?

[pieforme]

That didn’t seem to work, at least not in the frame buffer. But i noticed when I render out a sequence and save the files the velocity pass is there although it is corrupt I have set of another render with your fix I will let you know if it works.

The other issue I have been having which seems quite straightforward but I cant seem to work out in this scene and also in a simple test scene. I have a simple pflow with particles just emitting out for a 100 frames. I make an xmesh which works fine however when I retime it with the graph to finish at frame 50 it just disappears after frame 50, I have tried different loading modes and same issue. I am also having the same thing in my main file where object disappears after I retime it. The entire xmesh sequence is 1000 frames I have retimed it to 500 and after that it disappears, additionally say I just speed up the first 200 frames and have it end at 1000 then around 990 or so it disappears this is driving me a bit nuts.
xmesh_test.zip (2.8 MB)

[paul]

The other issue I have been having which seems quite straightforward but I cant seem to work out in this scene and also in a simple test scene. I have a simple pflow with particles just emitting out for a 100 frames. I make an xmesh which works fine however when I retime it with the graph to finish at frame 50 it just disappears after frame 50, I have tried different loading modes and same issue. I am also having the same thing in my main file where object disappears after I retime it. The entire xmesh sequence is 1000 frames I have retimed it to 500 and after that it disappears, additionally say I just speed up the first 200 frames and have it end at 1000 then around 990 or so it disappears this is driving me a bit nuts.

Thank you for your report! Could you please try the attached build?

I’ll take another look at the velocity pass issue.

[size=85]Attachments

XMeshLoader-MX-1.1.4.49723-64bit.zip (removed)
(3.52 MiB) Downloaded 90 times[/size]

[paul]

That didn’t seem to work, at least not in the frame buffer. But i noticed when I render out a sequence and save the files the velocity pass is there although it is corrupt I have set of another render with your fix I will let you know if it works.

I made a new scene based with two XMesh Loaders, loading the xmesh sequence you posted above. The velocity pass appears how I expect:

Here is my scene file:
two_xmesh_loaders_mental_ray_velocity_render_element.zip (20.1 KB)

Could you please try rendering this scene, and let me know the result?

(Also, please note that I posted a new build of the XMesh Loader for you to try above.)

[pieforme]

Hey Paul,

Thanks for the speedy response and solution. With the new build both the issues have been sorted. I am still having issues with the open exr velocity in my main file although its fine in the test file. However the render elements velocity seems to be good. I will have a look again when i get to work tomorrow but so far its looks like its good. Is this an issue with Pflow again as it was in the first instance?

[pieforme]

The other issue I have been having which seems quite straightforward but I cant seem to work out in this scene and also in a simple test scene. I have a simple pflow with particles just emitting out for a 100 frames. I make an xmesh which works fine however when I retime it with the graph to finish at frame 50 it just disappears after frame 50, I have tried different loading modes and same issue. I am also having the same thing in my main file where object disappears after I retime it. The entire xmesh sequence is 1000 frames I have retimed it to 500 and after that it disappears, additionally say I just speed up the first 200 frames and have it end at 1000 then around 990 or so it disappears this is driving me a bit nuts.

Thank you for your report! Could you please try the attached build?

I’ll take another look at the velocity pass issue.

FYI this also happens when caching out Frost objects.

[paul]

Thanks for the speedy response and solution. With the new build both the issues have been sorted. I am still having issues with the open exr velocity in my main file although its fine in the test file. However the render elements velocity seems to be good. I will have a look again when i get to work tomorrow but so far its looks like its good. Is this an issue with Pflow again as it was in the first instance?

There was a bug that caused things to blow up when the Timing Graph is flat. I’m really surprised that it went unnoticed for so long.

Did you manage to fix the velocity issue in your main file?

FYI this also happens when caching out Frost objects.

Sorry, I’m not sure what you mean. I just tested the Playback Graph in Frost, and it doesn’t seem to have the same bug as the XMesh Loader.

What kind of particle source are you using for Frost? For example, are you loading particle files through the Particle Files rollout, or using a Particle Flow system through the Particle Objects rollout?

Would it be possible for you to perhaps send me a scene file that reproduces this problem?

[pieforme]

Hey what i meant was that if you xmesh a frost object and retime it you get the same problem of the mesh disappearing, but after reading your post its basically the same bug.

“There was a bug that caused things to blow up when the Timing Graph is flat. I’m really surprised that it went unnoticed for so long.”

[paul]

Got it, thanks!