BIG Problem with motion blur & Element 3D!

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BIG Problem with motion blur & Element 3D!

Postby ImJim on 03/26/2019, 9:29 am

Hey guys,

I was adding 3D models onto 3D-Tracked live footage with E3D, when I noticed that enabling motion blur in the composition settings and on the Element 3D layer makes the tracking out of sync. Yup, you read me well. If I want to add motion blur to match the camera shutter speed (in my case 1/50 or 180° angle) the whole tracking data is slightly off. The layer "floats" around without sticking to the tracked point. And no, moving the layer by one frame forward or backwards doesn't do anything. As soon as you click on the motion blur icon, you can immediately see the layer and the null slightly changing their position, which confirms motion blur is making tracked layers off-track.

Here's a short video of a super basic test project showing you the issue in detail, please watch it closely! First composition I'm showing is a comp with motion blur turned OFF for the Element 3D solid. Second composition is the same but with motion blur ON.



Both comps contain:
- the tracked footage (25fps, 1/50 shutter speed)
- a solid with E3D opened
- a Null generated from the tracker
- a 3D tracker Camera generated from the tracker
- a group Null controlling the 3D model position.


► In the first comp (0:17 seconds in the video) with MB set to OFF, the track is pretty much seamless; as you can see, the plane model sticks at the top of the sound card, just sitting on top of the red line. (focus your attention on the bottom of the plane model)

► In the second comp, (0:30 seconds in the video) with MB set to ON, the track is completely ruined. The object floats around and doesn't stick to the top of the sound card. At 1:00 in the video, I'm showing you how turning motion blur ON and OFF makes the position of both the 3D object & Null shift in space.

Composition settings are: Shutter angle 180°, Shutter phase -90 (aka the exact settings used for 1/50 shutter speed footage)

I suspect Element 3D to be the cause. But I can't find the root of the problem. Adjusting shutter phase to -1/2 of the angle value (as advised by Adobe) doesn't change anything. Note that I don't have this problem when 3D-tracking 2D objects like solids or still images.

I verified the track was indeed off by making a pre-comp of the footage + tracked object and stabilized it with Warp Stabilizer. The track is completely off with motion blur, but perfect without.

Here's what I've done so far, with no luck:
- Re-installing After Effects
- Updating to latest version
- Converting the footage to H.264 MP4 instead of its original XAVC format
- Trying different shutter phase values- Using Force Motion Blur instead of the standard blur (same thing happens)
- Shifting the video by one frame forward or backward (makes it worse)


Has any of you noticed this problem and/or found a solution? I'd be so grateful if someone had at least a clue of where the issue comes from. Any other suggestions welcome. Thanks in advance!
ImJim
 
Posts: 2
Joined: 03/26/2019, 9:21 am
System Specs: Build: Element x64 2.2.0 (2100)

OS: Microsoft Windows 10 Famille 64 bits 10.0.17134

CPU: Intel(R) Core(TM) i7-6700HQ CPU @ 2.60GHz
RAM: 24436MB

GPU Vendor: NVIDIA Corporation
GPU: GeForce GTX 960M/PCIe/SSE2
GPU Driver: 21.20.16.4550
GPU RAM: 2048MB
GPU Code: 0

CL0: GeForce GTX 960M (47.6%) (GL Interop)
CL1: Intel(R) HD Graphics 530 (47.6%)
CL2: Intel(R) Core(TM) i7-6700HQ CPU @ 2.60GHz (4.8%)

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