BIG Problem with motion blur & Element 3D!

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BIG Problem with motion blur & Element 3D!

Postby ImJim on 03/27/2019, 5:58 pm

Hey guys,

I was adding 3D models onto 3D-Tracked live footage with Element 3D, 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 off. When previewing, it looks like the tracking position is off by one frame: the layer lightly "floats" around without sticking to the tracked point. 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.

I suspect the 3D camera created by the Adobe camera tracker to be part of 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 with 2D tracking at all.

I verified the track was 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 a short video of a super basic test project showing you the issue in detail, please watch it closely!

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)
Again, making a pre-comp and adding CC Force Motion Blur yields to the exact same issue.

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.

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 RSMB or Pixel Blur, WAY too CPU-hungry, previewing takes forever; not a solution
- Using Force Motion Blur instead of the standard blur (same thing happens)

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!
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:
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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