Motionvector AOV doesn't work in 3DS Max

[Anonymous]

In 3DS Max Arnold 6.2.2.1 when I create a motionVector AOV I get no motion data (a black channel image). So I opened an old scene and everything is working fine. I then deleted the MotionVector AOV and immediately recreated it (same camera, same scene, same settings). The result I get is, again, a black channel (empty).

Is there any know bug for that AOV? Can someone help me please?

[madsd]

I just tried this in A7.
First run gave me a black renderer.

Dev will see the thread later today.

[Anonymous]

Thanx Mad Dreschler

[osukas]

There is a way how to do customized AOV to get motionvector data?

[Stephen.Blair]

How was the motionvector AOV defined in the old scene?

With MAXtoA 5.0.0.93, if I create a custom AOV, rename it to motionvector, set the type to RGB, and the filter to closest, I get motionvectors.

The other alternative would be the motion vector shader.

[Anonymous]

Hello Stephen,

originaly the motionvector AOV was defined with the data AOV of the same name. Motion blur was activated both on the camera and the Instantaneous Shutter for Motion Vector parameter.

I've tried to create a custom AOV as you did but it doesn't work. So I tried with diffrent types (RGB, Vector ans Vector2. Still no data. I created another AOV which I name RGBA_MV (like in Maya I think)... Nope. So I tried every type... Still no data.

I also tried the MotionVector map only and then the motion vector map with the AOV Write RGBA and then again with the AOV Write Vector shaders without succes.

If I use th Arnold renderview Debud Shading tool, I see data for every AOV I create (but there's no vector parameter in this tool).

As I was saying, if I open an old scene and everything is working fine (like your pool balls scene) and then delete the MotionVector AOV and immediately recreated it (same camera, same scene, same settings). The result I get is an empty black channel (no data).

I've been teaching 3Ds Max since 2002, so I'm not a newby. Furthermore the motion vectors AOV worked fine 2 years ago with Max 2020 Now that we've updated to Max 2022, it doesn't work, even with the same compouter. Wish I didn't desintalled my 2020 version to test it further.

Thanx for your help.

[Anonymous]

1- Create motionvector AOV with closest filter
(By the way there is a little bug, normally when you create the motionvector aov you don't have to change the filter since it defined in aovs.py file)
aovs.py line 113
defaultFiltersByName = {'Z' : 'closest', 'motion_vector' : 'closest', 'P' : 'closest', 'N' : 'closest', 'Pref' : 'closest', 'ID' : 'closest', 'AA_inv_density' : 'heatmap', 'volume_Z' : 'closest' }

2- Enable Motion Blur in Arnold Renderer
3- Ignore Motion in Diagnostics
and you have it!
same setup for all DCC

[Anonymous]

Hello Rachid,

thanx for your help but it doesn't work. Every other AOVs are working fine though.

As I was saying, if i use a scene where it does work (an old scene) and I delete the motionvector AOV and replace it by an other one with all the same parameters (same scene, same camera same object, same material, motionvector AOV, filter "Closest"), it doesn't work anymore.

[Anonymous]

Can you make a fresh scene?
- a simple sphere with some keys (translate/rotate)
- Motion Blur: Enabled
- Ignore Motion in Diagnostics
- apply motionvector AOV
Here I have 02 pass:
motionvector Aov and custom mv with aiMotionVector Shader
Defaut motionvector Aov
Custom mv with aiMotionVector Shader

[Stephen.Blair]

It's a bug (a regression: a feature that worked before and now doesn't), and I logged it.

I did got motionvector data (as shown in the screenshot). You do have a physical camera?
Other AOV names won't work.

[Anonymous]

Hi Stephan,

thanx for your help.

Yes I'm using a Physical cam. I also tried without a camera just to test it further. Same result. As- you can see in this screenshot, there is no data in the MotionVector AOV.

MotionVectorLess.png

[Stephen.Blair]

I checked the example file from the documentation, and I was able to get motion vectors in it.

1) The original motionvector AOV in the sample scene.

2) A new motionvector AOV that I created (it didn't give any motion vectors)

3) A "mv" custom AOV that I renamed to "motionvector"

[Anonymous]

I don't know about 3dsmax, but in Maya & Houdini, you have to enable motion blur first in Arnold Render, then ignore Motion in Diagnostics to get motionvector AOV working, and this was always like this since version 0.1!

[Stephen.Blair]

It changed for all plugins when Instantaneous Shutter was introduced, back in March 2019.

For MtoA, that was MtoA 3.2.0

https://docs.arnoldrenderer.com/display/A5AFMUG/3.2.0

• Improved workflow for motion vectors AOV: new attribute Instantaneous Shutter in the motion blur settings allows getting correct motion vectors AOV while rendering a still image. The shutter range will now be taken into account in the AOV.

[Anonymous]

Can we get motionvector AOV without enabling Motion Blur in Arnold Renderer?

[Anonymous]

take a look here
https://youtu.be/pzOAeO2pyQw

[Anonymous]

Hi Rachid,

the bug is in 3DS Max not in Maya. 😉