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Target Image coardinate in camera screen

August 10, 2012 - 7:42am #1

Hello Vuforia Team

       can you help me to find target image coardinate on phone screen, four corners coardinate on camera screen.


       find the size of target image on phone screen, 

 please help me to find any one of above things, it is importent to my project friends, please help me urgent




Target Image corners in camera screen

August 11, 2012 - 12:03am #3

Hi thanx for replay,

 but i need a corners coardinates, for target image four corners that coardinates i need on phone screen



Target Image coardinate in camera screen

August 10, 2012 - 10:17am #2

You can do this using the projectPoint function..

QCAR_API Vec2F QCAR::Tool::projectPoint ( const CameraCalibration &  calib,
    const Matrix34F &  pose,
    const Vec3F &  point 

Projects a 3D scene point into the camera image(device coordinates) given a pose in form of a 3x4 matrix. The projectPoint() function takes a 3D point in scene coordinates and transforms it using the given pose matrix. It then projects it into the camera image (pixel coordinates) using the given camera calibration. Note that camera coordinates are usually different from screen coordinates, since screen and camera resolution can be different. Transforming from camera to screen coordinates requires another transformation using the settings applied to the Renderer via the VideoBackgroundConfig structure.

Here is how you obtain the camera calibration ..

    const QCAR::CameraCalibration& cameraCalibration =
    projectionMatrix = QCAR::Tool::getProjectionGL(cameraCalibration, 2.0f,


See the _renderFrame method in the samples for an example of how to obtain the pose of an active trackable.

Here are some examples - https://ar.qualcomm.at/content/find-trackable-xy-position-screen

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