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Any way to control the distance?

April 9, 2013 - 11:05am #1

we are currently experimenting with trackers.


Something that puzzles us is the in-unity distance in relation to the target actual distance as perceived by the camera.


In one version of the tracker, the distance camera-tracker at 30 cm corresponded in  about 300-400 unity units, while the current one we are using correspond to about 1600 unity units for the same camera distance.


Do we have any control over the distance conversion?

Any way to control the distance?

April 9, 2013 - 1:43pm #5

Yes you can rescale MTs, though you'll want to ensure that you apply the scale factor uniformly to all of the child targets. Then go to Vuforia > Apply Dataset Properties in the Editor menu to update the MT in the scene with your changes.

Try using 'real' measurements. You shouldn't be seeing a 5X discrepancy. That suggests a problem w/ scale / unit conversion.

Any way to control the distance?

April 9, 2013 - 1:40pm #4

I figured there was something somewhere, even in the multitargets!

Can we alter the width within the XML, or do we have to reprocess the images in the Target Manager?



For 2D trackers, it is fairly simple... sad we can't scale the 3D multitargets the same way.

We don't need super accuracy, but having a distance & size discrepency that large (up to 5 times larger/farther) was a huge concern.  Without control over the "distance" of the objects, object physics is rendered very difficult... but if we can approximate it from the target's width, its a start.

Any way to control the distance?

April 9, 2013 - 1:34pm #3

The width value defined for the target in the Target Manager is adopted as the unit scale for the Unity scene. This is why you'll see discrepancies in the distance measure between Vuforia targets, which provide for custom scale definition, and other SDKs that do not.

If you're trying to derive a standardized distance measurement, my advice is to define your target width by its measured width in whichever unit of measure you want to use (e.g. CM, MM, Inches et. al. ).

Also the Play Mode simulation is not going to be as accurate as device based measurements, so don't use Play Mode to verify the precision of your measurements.

What is the result that you're looking for, to accurately measure camera distance?

Any way to control the distance?

April 9, 2013 - 11:17am #2

Again answering my own question. I am getting good at this thing :D

changing the scale will work with that. However, changing the scale in play mode will result in a smaller but still distant tracked object, which is somewhat confusing.


In the documentation, I had read about "when created in the TMS" and "scaling" but the secret is to scale the tracker transform accordingly prior to running and detecting.


However, for 3d objects (multitarget) we need to edit the xml file. Its more puzzling. I cannot seem to achieve any good results... any ideas?

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