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Change the tracking

By pocahantez on Fri, 03/22/2013 - 11:26

Hi,

Looking into the vuforia SDK samples i notice that the tracking of the target is done with feature matching. Since my object doesn't have a good quality of feature,i wonder can i then add a new tracking algorithm? have any one done it before?

AlessandroB

Fri, 03/22/2013 - 11:44

Permalink

Hi,

yes, if you like to implement your own computer vision and tracking algorithms, nothing prevents you from doing it;

for information, this article explains how you can retrieve the camera image from Vuforia, so that you can process it the way you want:

i'm using the UserDefinedTarget example.how can i access the target image?i know that the data are stored in a data set but i want the target as an image.

You cannot obtain the image of the target created via UDT; the API does not expose it.

One thing you can do however is to capture the Camera frame image at the time when the UDT target is built.

To do that, you can use the QCAR::State::getFrame() API.

IS it possible to define my own feature point and added it to the dataset to be tracked later?For example define a model in the begening of the camerastart and fix the points that i want to add to the dataset ,then match this points  for the tracking.really i don't know which algorithm i

No, you can't explicitly put your feature points into a dataset; the Vuforia API does not offer such possibility.

Basically, if you need such low levels functionalities, you will probably need to use some computer vision library and implement you own detec tion and tracking system.

thank you ,i have changed the tracking method now i want to render a 3D object as it is done on the original code of ImageTargets sample.so that i changed the render_frame method  exactly in the modelView matrix but i have a fix 3D teapot.it seams to be attached to the mobile screen not to t

i wan to disable the rendrering of the teapot if my target (in my case it is a marker with a bad feature so that i change the tracking method) doesn't exist.

then i should render my object  in the center of the marker. 

Ok, to render the teapot in the center of the target, you can use the ImageTargets code "as is", i.e. without any modifications;

I 'm using UDT with the ImageTarget sample. Now i have three image target and i want to enable the rendering of the 3d model  as one of this 3 target is shown on the screen.

 i found in the forum this 2 line :

Thank you ,it's really helpful (i'm using the ImageTarget Sample) but i have now two teapot shown on the screen :one due to the target1 and the other for the target 2.

I see. If you need to show just 1 model when the 2 targets are found, there is nothing specific in the Vuforia SDK that you need to do,

it's just application logic and a bit of good C++ programming.

 

hi i have read a lot of thread and vuforia API Dev but i 'm  confused about the getpose() function? how does the modelviewmatrix was filled.thank you in advance

Hi,

the modelview matrix represents the rotation, translation and scaling of the model with respect to the camera;

it is a 16-elements array (which represents a 4x4 matrix); the structure of the matrix is explained in great detail here: