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ImageTarget tracking problem

March 24, 2019 - 7:07am #1

Hi everyone, I'm using Vuforia with Unity and I try to track an ImageTarget( that with stones from Vuforia site). The problem is that sometimes (in 20-30% of  cases) it takes like 10-20 seconds to recognize the ImageTarget even if I put it very clearly in front of the camera. Other problem is when the ImageTarget disappears from the scene and reappears sometimes works perfectly sometimes not. Any suggestion why this is happening? (I'm new in Vuforia)

ImageTarget tracking problem

June 6, 2019 - 3:33pm #7

Hello @holo112,

Vuforia recommends that an Image Target's size match the printed materials. As meters are the Unity default scene units, a 28 cm printed image would be specified as 0.28 in the Target Manager.

Thanks,

Vuforia Engine Support

ImageTarget tracking problem

June 6, 2019 - 8:40am #6

Another question, if I have a printed image that has 28 cm that I want to use as a marker, what width I should set in the target manager for that image (0.28 ) ?

ImageTarget tracking problem

April 12, 2019 - 3:24am #5

@medabit

There is no problem detecting my ImageTarget but it jitters from time to time even the camera is close to ImageTarget (not too close of course).

I have read the article about stability you mentioned and jittering remains after the camera focus mode is set to FOCUS_MODE_CONTINUOUS_AUTO.

I am wondering if there are more specific suggestions about lighting conditions, for example color temperature, video reference about light setup etc.

"enough light" is just too abstract for users to confirm whether the problem is caused by ImageTarget itself or light condition

 

Thanks

ImageTarget tracking problem

March 29, 2019 - 4:49pm #4

Hello,

This could be related to your target and/or your environment. I suggest you start by reviewing best practices for your target to insure it is performant:

https://library.vuforia.com/articles/Solution/Optimizing-Target-Detection-and-Tracking-Stability

Some additional tips:

  • Always print the image that was uploaded to the portal to the exact same aspect ratio. Some printers default to "stretch to fit", which can change the aspect ratio.
  • Check the size values you are using when uploading Targets to the Vuforia Target Manager. Note there is specific language used in the dialogue box that says Vuforia uses meters as the default unit scale. Incorrect target sizes could affect either our detection/tracking algorithm
  • Image Targets must be flat when in the camera's field of view
  • Not enough lighting upon, and/or spectral reflections occluding the Image Target

Thanks,

Vuforia Engine Support

ImageTarget tracking problem

March 28, 2019 - 8:37am #3

I used the laptop  webcam to test (720p webcam laptop:Lenovo Legion Y720) and after I deployed the application on a Huawei P20 lite and had the same result ( sometimes worked perfectly sometimes didn't detect at all). I dont understand why this happen, I add this code in the DefaultTrackableEventHandler script from an ImageTarget:

protected virtual void Update()

{

calculateLength();

}

protected virtual void calculateLength()

{ Vector3 delta = Camera.main.transform.position - mTrackableBehaviour.transform.position;

float d = delta.magnitude/28 ;

Debug.Log("The distance is : " + d +"cm");

}.

Can this affect the ImageTarget detection?

ImageTarget tracking problem

March 26, 2019 - 9:29am #2

Hello,

This is unusual behavior. Detection should not take that long unless the device camera is of poor quality, or if the input image is blurred due to a lack of focus.

What device are you using?

Thanks,

Vuforia Engine Support

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