After importing the FBX of the camera tracking data to UE4, the position is different.

FAQ Content Creation Bugs 3D Animation Sequencer Video Playback Camera Tracking Unreal

 

    I used Record 3-Audio to record the tracking data of the camera in Aximmetry, and imported the FBX into the Sequencer of UE4 and found that the position of the camera was incorrect.

    This is the footage recorded by Aximmetry.


This is the screen after importing FBX into UE4 .

This is my setting .

I don't know why this happens. Is it to be used in other 3D software? Can anyone help me solve this problem, thank you very much .

   ChengJH

 
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Zoltan@Aximmetry
4/9/2021 2:02:10 PM
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Hi Cheng,

We've tested it with Maya.

Did you use the default time code?

Is the camera moving (just on a wrong path), or is it just sitting still in a wrong position?

 
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Base2 Video Factory
4/9/2021 2:48:59 PM
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Hi cheng,
How did you manage to import axy's fbx back to unreal? When I try to do it, i recive this message in unreal's output log and can't import the tracking datas 

 
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ChengJH
5/4/2021 8:23:21 AM
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Using the sequencer in UE4


 
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Crossroad1000
5/6/2021 8:04:17 AM
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We are having the same problem here. 

The data is recorded but the position of the camera is not correct according to the position of the scene. 

@ Cheng, did you found a solution? 

 
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ChengJH
5/7/2021 11:10:14 AM
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It doesn't work. Maybe it works in Maya or 3DMAX. But I don't know how to use the FBX file correctly in UE4.

 
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AxiTry
5/11/2021 3:30:48 PM
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I am having a similar issue.

I have tried importing into MAYA, Blender and Unreal but my fbx always come with 0 keyframes.

Right now the only way I can record tracking data is with the tracked camera compound  and render it in the  sequencer.

 
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guyamit
5/18/2021 12:27:23 PM
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Same is here, I do manage to import to Unreal, and I get the keyframes, but the origin of the camera is wrong

 
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Funkdigit
6/11/2021 11:07:30 AM
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I believe this may be related to incorrect scaling of the FBX camera data.

Looking at a test I've just completed, (simple Vive tracking to FBX, FBX into C4D), all my tracking / camera positions are contained within a 1cm cube. This gives the impression of being stuck in the floor / incorrect origin, but if one zooms in you can see the correct movements are recorded, just with the incorrect scaling.

Zoltan@ - When you say "We have tested in Maya" can you confirm you see correct scaling / postioning of camera data via FBX that matches the recorded footage? FBX is pretty universal - if it works in Maya, we should see same results in C4D / UE4 / MAX etc..?



 
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Funkdigit
6/11/2021 2:31:49 PM
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Potential fix for the above scaling issue in UE, (same technique may work in other Post software).

Make a Camera in UE4 level. Also make a simple null (eg a cube). Ensure rendering of the cube is set to not visible (but is Actor is NOT hidden in Game), and ensure cast shadow is off for the cube. Parent the Camera to the null. Ensure Cube is Location 0,0,0 and add +90 to Z rotation of cube.

Now lock the scale of the cube and set scale to 100. Transforms for the actual camera will be set via FBX import (see next).

Now make a level sequence. Import the Camera you made above, and set it to the current camera cut track. Right click on the camera in sequencer, and import (FBX animation to this object). Ensure no options are ticked, then click import. Lock viewport to Camera Cut (click the camera icon on Camera Cuts track). Hit play, then scrub / play through the level sequence to check correct camera orientation and movement / scale.

Cheers.

 
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Zoltan@Aximmetry
7/1/2021 1:56:15 PM
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Hi Funkdigit,

Thank you very much for sharing your findings and solution.

Aximmetry, indeed, exports the data in meters, since it is the base unit in Aximmetry.

It's possible that it is not indicated explicitly in the file and UE interprets it in cm.  We'll look into it, thanks again.

 
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DeataProduction
7/25/2021 2:04:05 PM
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Aximmetry records the fbx with units as meters, unreal works in centimeters that's why it appears to be stuck on the ground..

Camera is at 1.32m in aximmetry ----> 1.32cm in unreal.

You need to convert the world scale on the fbx file to centimeters.

 
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Aximmetry
7/30/2021 11:34:20 AM
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Hi,

FBX format contains unit information, but unfortunately we forgot to set it properly. So as you wrote it has to be converted manually now. We will fix this error in the next version. So conversion will be automatic. Sorry for the inconvenience.

As a side note: if you provide a transformation to Unreal (using Get Aximmetry Transformation) then we automatically convert the unit (and coordinate system) For everything else (for example if you just provide a vector that you want to use as a position in unreal) you have to convert it manually.

(FBX is another exception since it has unit and coordinate system information)

Best Regards


 
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guyamit
8/3/2021 12:36:04 PM
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Hey, I'm facing a similar problem and have tried Funkdigit's solution, but in my case when importing the FBX into UE4, I get this error-

The FBX cannot find a matching camera and imports into the sequence without any keyframes.

Other than that, I've tried importing the FBX file into Maya to check if it is working okay and found out that other than being small (in cm)


it had close to a million frames to the animation with only a few keyframes near the end of the animation. But the keyframes were empty as well- didn't change the position of the camera or anything.


 
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Aximmetry
8/10/2021 7:52:11 AM
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Make sure that "Use Input TC" or "Use Master TC" is turned off.
https://aximmetry.com/learn/tutorials/for-studio-operators/recording-camera-tracking-data/#timecode
Otherwise, your recording's keyframes will start from the frame number derived from your camera's internal timecode. (Which is necessary in some application, but not when you import it to another 3d applcation)

Also, for example, if you are using "Record 3-Audio", then make sure that "Record Data" of "Record 3-Audio" is connected to your "TrackedCam", otherwise the keyframes won't record your camera's position.

Best Regards