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Extended Tracking doesn't work

August 1, 2018 - 1:57am #1

Hello everyone,



I'm making an app using Vuforia 7.2.24 and Unity 2018.1.7f1, where I track an object target.

The object has 69 points. The scene works but each time the tracker is lost, the camera position is reset.

Device Tracker is enabled, with the tracking mode set to "positional" and the fusion mode set to "optimize for image target and Vumarks"

Extended tracking works when I use Image target as tracker.



Any solutions ?

Extended Tracking doesn't work

August 2, 2018 - 11:09am #2

Hello,

There are many factors that can affect the tracking performance of a Object Target, both during the scanning process and when running an app. Most issues with Object Targets can be traced to the creation of the .od file using the Vuforia Object Scanner. Be sure to follow the scanner app instructions: https://library.vuforia.com/articles/Training/Vuforia-Object-Scanner-Users-Guide, paying close attention to step #8 in the article.

  • When creating the .od file, was the model scanned in an environment that was free of background details which may have introduced features that were not part of the model? Scanning in 'cluttered' environments can introduce false detection/tracking points.
  • When creating the .od file, were there any specular reflections on the model introduced by environmental lighting? Scanning objects that have reflective surfaces under direct lighting can introduce areas with no detection/tracking points.
  • Are you using the recommended devices referenced on the tool download page?: https://developer.vuforia.com/downloads/tool

In our labs, we utilize four primary strategies for creating an optimal Object Target scanning environment:

  1. All background surfaces are colored at 18% gray. An easy, off-the-shelf solution is to buy bed sheets near this color and drape everything in the environment that could be seen by the scanning device's camera.
  2. No direct lighting. We use light boxes and/or diffusers to eliminate direct lighting upon the object and minimize any spectral reflections.
  3. Utilize a 360 turntable to re-orient the device. This is especially helpful when you've set your environment to near ideal conditions within a limited area. You can spin the model and scan in 360 degrees without having to move around it.
  4. Be sure that the environment in which you’re testing (via the Object Scanner app ‘test mode’) is the same in which you’re verifying tracking (via the sample code). Environmental factors such as lighting, shadows, spectral reflections, etc. can negatively affect tracking performance, so awareness of how the environment is interacting with your model is important for qualifying performance.

The low number of keypoints (69) from the scanning phase is concerning for performance. We advise that objects should have 150+ keypoints for best performance.

Thanks,

Vuforia Engine Support

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