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[Framemarker] real-time detection?

April 26, 2013 - 2:03pm #1

Just did an exp: display the same image but with two time varying framemarkers, like marker 0 and maker 1. The period of each marker is 1s. Codes from framemarkder can do the tracking in realtime, but not for detection. Once the 1st detected marker is marker 0, then the rest will be recoganized as 0, though marker 1 is being displayed.

Check the codes. The tracking & detection happens in JNI "Java_com_qualcomm_QCARSamples_FrameMarkers_FrameMarkersRenderer_renderFrame", when the onDrawFrame() function is called in the class FrameMarkersRenderer. Since by default in my settings, only one framemarker is displayed, I adapted the codes as follows:

	if(state.getNumTrackableResults() == 1)
    {
		const QCAR::TrackableResult* trackableResult = state.getTrackableResult(0);

		// Check the type of the trackable:
		assert(trackableResult->getType() == QCAR::TrackableResult::MARKER_RESULT);
		const QCAR::MarkerResult* markerResult = static_cast<const QCAR::MarkerResult*>(trackableResult);
		const QCAR::Marker& marker = markerResult->getTrackable();
		int textureIndex = marker.getMarkerId();
		LOG("Frame %d is detected.", textureIndex);
     }

What's wrong with realtime detection? Any suggestions on correction? thx.

[Framemarker] real-time detection?

May 1, 2013 - 12:09am #4

OK, thanks for the clarification;

the thing is that detection runs as a background process and can take a little bit of time (compared to tracking); so in that sense, it's not strictly "realtime" (just to use your definition);

once a marker is detected, then the tracking process starts; so, it could be that when you suddenly switch the marker in you sequence, the tracker keeps tracking the marker as if it was the old one (while the detector might realize the change only after some time).

 

[Framemarker] real-time detection?

April 30, 2013 - 7:05pm #3

Display a video sequence of framemarkers. In each frame there is only one framemarker.  The order of displayed frame markers is index0->index1->index2... I find tracking can be realtime however detection is not. Usually the detected sequence is always the same as the first detected frame, for example index0, though at that time index5 is displayed there. My question is: is detection also as realtime as for tracking? Any reference to the framemarker algorithm? Sorry for the confusion.

[Framemarker] real-time detection?

April 28, 2013 - 1:05pm #2

Hi, sorry but I'm afraid I don't understand what you are trying to do and you question.

 

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