Regarding Tracking Delay and Studio Values

Studio Operators Content Creation Composer Camera Tracking Unreal

 

Hey,

Since we began using Aximmetry for production more than a year ago, we had a couple persisting issues that we need to fix for production-

1. The tracking delay is very inconsistent- We are currently using two trackers (Anti Latency and also testing REtracker BLISS for a while) and we're encountering this problem with both of them and every other tracker we had in the past. After a few minutes of using the tracker and moving the camera around, the tracking delay value needed to lock down the talent to move with the environment changes completely. Usually we are using them with genlock- set to 25fps and with REtracker BLISS we have also tried to use the tracker in Free Run mode at different tracking fps such as 1000, 500 and 300.
Regardless the tracking delay still  goes out of sync.
We have also done a bit of testing- leaving the system with the trackers on for a long time (about a day) without moving the tracker after locking down the tracking delay and it seems that the tracking delay stays locked as it should- The problem occurs only after a few minutes of actively moving the the camera and tracking.
Also from what we've understood when using the trackers directly with Unreal Live Link, this problem doesn't occur.

2. The Studio values changes when re-opening a compound- When setting up our project, we are also setting up the required studio values to get the correct crop that works for us. The next time we are opening the project or another project and copy these values, they don't work the same anymore. The studio rotation changes and the ceiling and such don't match the same as they did when we've set them up when creating the project.

Any help on these matters will be greatly appreciated as it always delays our shooting and leads to some undesired results a lot of the times.


Thanks in advance,
Virtuals.tv Studio

   guyamit

 
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TwentyStudios
6/22/2022 9:28:18 AM
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I don’t know what’s going on here, but how are you genlocking Antilatency? 

 
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guyamit
6/22/2022 9:42:21 AM
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I've made a mistake when making the post what I meant is we have everything genlocked and have also tried using REtracker genlocked.

 
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TwentyStudios
6/22/2022 10:03:11 AM
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If the tracking system isn’t genlocked, you’ll see no tracking accuracy benefits with genlocking the camera or video card output. Aximmetr will genlock to the video input (if you check the Sync option) even if the camera or capture card itself isn’t genlocked. 

 
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guyamit
6/23/2022 9:04:20 AM
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Yeah, we've tried genlocking REtracker but that didn't solve the tracking delay changing over time, only made tracking less accurate than Free Run mode.

 
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Eifert@Aximmetry
6/30/2022 11:48:16 AM
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Hi Guyamit,

1.,
Are you sure that the REtracker BLISS is genlocked with your camera and the tracking?

In the case of tracking that is not genlocked (Anti Latency), you could try to reduce the delay, and then maybe the change in the delay over time will also be reduced. Are you using a wired Alt (Antilatency tracker)? If so, how it is wired? How big a delay do you need to set in Aximmetry?

2.,
It should not happen that Aximmetry loses studio settings when loading a project. Instead, It is likely that tracking changed and it has a different zero-point now and that is why you experience the changes.
When antilatency is turned off, it doesn't save its last location, so when you turn it off next time, it will have a different zero-point. If you turn on and off the camera in the same real-world position then this will be less noticeable.

Also, you can easily copy settings between the same control board using the Save Settings... context menu option:

Warmest regards,


 
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TwentyStudios
6/30/2022 12:12:21 PM
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@Eifert: This doesn’t make much sense. Why would they reduce the delay? The point is to line it up exactly with the camera delay, right? If they’ve done that but the delay varies over time, there must be an issue somewhere. Since they’re seeing this with both ReTracker and Antilatency it’s likely there is an issue somewhere in Aximmetry that is causing this.

Antilatency shouldn’t change zero-point. It’s an absolute tracking system, like MoSys StarTracker or Stype RedSpy, so unlike with ReTeacker it shouldn’t need any calibration between runs. 

 
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guyamit
7/4/2022 7:56:30 AM
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@Eifert

Hey Eifert,

1. I am sure that REtracker was genlocked. As I said, we've tried using both the genlocked mode and the free run mode (up to a 1000 fps tracking).
We are still experiencing changes in the delay regardless...
If we'll reduce the delay with Antilatency, we'll simply get the wrong delay and the talent would look disconnected from the virtual environment.
With Antilatency we've also tried quite a few ways of wiring it including connecting it to the PC with optic cables, long USB, and our current setup which is the tracker connected with a short USB cable to a mini PC mounted on the camera that is connected to the rendering PC with a network cable.
The usual delay we have to set for Antilatency is around 0.3-1.3, always changing- both over time and also when loading up a project again.

2. As TwentyStudios replied, why is Antilatency changing it's zero point? it is always the same ceiling setup, shouldn't the studio settings stay the same as well?
What can we do so we don't have to go through setting up the studio each time?

Thanks,
Guy


 
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Eifert@Aximmetry
7/8/2022 8:25:15 AM
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Hi,

1. I meant by reducing delay by reducing the amount of hardware. It seems you have already done a lot on that front, like the optic cables instead of the long USB. 0.3-1.3 delay change doesn't seem to be too much. Note that the delay in the Input panel is counted in frames.

If genlock works correctly the delay should not change. Note that most likely the genlock mode won't work with the free run (1000 fps) mode. Also, your camera and capture card also needs to be in a genlock state.

2. TwentyStudios is right Antilatency does not change the zero point. Sorry for the confusion.
When reopening the compound, it shouldn't change any of the settings.
You can check if the camera's position changed with the Cam Transform pin, like this:

If things go wrong when copying, then a detailed description of how you copy the studio values could help figure out where is the issue.

Warmest regards,

 
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TwentyStudios
7/9/2022 4:14:12 PM
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@Eifert: Since Aximmetry is genlocked to the video input, there shouldn’t be a variable delay to tracking if it’s received at a steady 1000 FPS. That is, if it’s actually implemented correctly in Aximmetry. There’s also a difference between delay variability and delay drift. If the delay increases over time but is steady between frames, there is definitely something that’s not right. In my limited tests I’ve also experienced an increase tracking delay over time. This has now been reported by many different users (who also reports it’s working fine in vanilla UE4) , so I think it definitely warrants further investigation by Aximmetry. Again, genlocked cameras or not, there shouldn’t be a delay drift between the camera and tracking data over time.