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How many image targets can be tracked?

August 7, 2012 - 6:16pm #1

Hello, I am a new comer to Qualcomm AR. I have one question about how many image targets can be tracked at the same time.

According to Dev Guide: "The Vuforia SDK not only allows multiple input images in the database, but it can also detect and track up to five targets simultaneously in the camera field of view."

However it aslo says in Dev Guide: " Note that at any given time only one dataset can be active. This active dataset is used by the ImageTracker to find and track targets in the camera’s field of view. We recommend that each dataset have no more than 50 trackables."

Below are my questions:

1. What's the relationship with Image Target and Dataset?

2. How to understand "track up to five targets" and " each dataset have no more than 50 trackables" ? Does one target match to one trackable?

Thanks in advance.

 

How many image targets can be tracked?

August 8, 2012 - 9:21am #4

Which SDK are you using?

For the native SDKs, use the following..

QCAR::setHint(QCAR::HINT_MAX_SIMULTANEOUS_IMAGE_TARGETS, 2); // for a maximum of 2

For Unity you'll set this value in the Inspector for the ARCamera in the Max Simultaneous Image Targets field.

How many image targets can be tracked?

August 8, 2012 - 6:19am #3

David, thanks for explaination about detecting and tracking.

I know ther is a API to activate and deactivate dataset. However I can't find API to know which 5 trackables are been tracked. Is there a way to choose 5 trackable been tracked among all 50 trackables in one dataset?

 

How many image targets can be tracked?

August 7, 2012 - 7:32pm #2

Yes an ImageTarget is a type of Trackable, as are FrameMarkers and MultiTargets.

A DataSet is a collection of Trackables. We recommend a maximum of 50 Trackables per DataSet. You can load multiple DataSets to include more Trackables, but only one DataSet can be active at a time. These can be activated and deactivated at runtime.

It's helpful to recognize that there is a distinction between detection and tracking. Detection is the process of recognizing an image from a set of images. Tracking is the process of determining the pose of that image relative to the camera, and is computationally intensive. This is why there is a limit to the number of Trackables that can be tracked simultanously, and why there is a distinction between tracking up to 5 images and detecting from 50.

 

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