Log in or register to post comments

re-scan an image target

May 27, 2019 - 4:23am #3

What is the recommended way to re-scan an image target? This is a hololens application using Unity & Vuforia. An image target is scanned and the 3D model is displayed just fine. But, when a user moves the hololens too close to a surface the image "Trying to map your surroundings" pops-up indicating tracking loss. After the user moves back from the surface tracking is re-established but once in a while the location of 3D model has changed dramatically and the image target should be re-scanned.

From what I can gather from the documentation and forums is that I should delete the database containing the marker and then read the database back in again. Which should allow me to scan it again and thus establish it's proper place again. Is that correct? It seems a bit of a long winded way of going about it. I would expect something like marking the image target as "undiscovered" after which it would be available for "discovery" just like any other image target in the database.

Thanks for your feedback.

re-scan an image target

June 4, 2019 - 5:05pm #2

Hello,

MrJigs wrote:

What is the recommended way to re-scan an image target? This is a hololens application using Unity & Vuforia. An image target is scanned and the 3D model is displayed just fine. But, when a user moves the hololens too close to a surface the image "Trying to map your surroundings" pops-up indicating tracking loss. After the user moves back from the surface tracking is re-established but once in a while the location of 3D model has changed dramatically and the image target should be re-scanned.

To clarify, the "Trying to map your surroundings" is a HoloLens message and not Vuforia, although it does affect Vuforia Engine's functionality and performance as we are dependent upon HoloLens spacial tracking for augmentation placement.

MrJigs wrote:

From what I can gather from the documentation and forums is that I should delete the database containing the marker and then read the database back in again. Which should allow me to scan it again and thus establish it's proper place again. Is that correct? It seems a bit of a long winded way of going about it. I would expect something like marking the image target as "undiscovered" after which it would be available for "discovery" just like any other image target in the database.

Actually, we have a method in our Unity Sample for HoloLens that demonstrates best practice for resetting the trackable, consisting of the following steps:

  1. Stop the tracker
  2. Deactivate the dataset
  3. Activate the dataset
  4. Start the tracker

Look for the code in the Reset() method in /Assets/SampleResources/Scripts/VoiceCommands.cs of the HoloLens sample on the Unity Asset Store.

Thanks,

Vuforia Engine Support

re-scan an image target

June 13, 2019 - 12:24am #1

Thanks for your answer. I did happen to stumble across that piece of code myself and it did solve the problem of re-scanning.

Log in or register to post comments