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Strange evaluation of an image by the Target Manager

June 6, 2013 - 7:00am #1

Hello Vuforia Team,

For one image we don't understand, why the target Manager give only 0 star... When we click on the link "show features", it seems that lots of recognition point are found. Generally, this type of images get more or less 3 stars (the main difference is that it's majoritally black). The more surprising thing, is that it perfectly works with mobiles and tablets on which we have test it (We use the Vuforia 2 Unity extension)...

I can't post the image here because the picture is a property of one our customer. But I can send it by private message is needed.

Why it obtains 0 stars ? Is it a bad evaluation of the target manager or do you think it's unsafe for us to use this type of tracker ?

Best Regards,

typtohms

Strange evaluation of an image by the Target Manager

June 7, 2013 - 12:23am #6

The reason is most likely in the "local contrast";

when changing the background color to white, the features appear more "contrasted" according to the Target Manager, which results in the increased star rating.

Strange evaluation of an image by the Target Manager

June 6, 2013 - 9:44am #5

Thank you very much for this feedback Alessandro ! We will see to optimize our futures trackers in accordance to your advices.

Nevertheless, that I don't understand, it's why it works well on devices ? (I'm not the only user which have tracker with 0 star, but however works like we can see in this thread https://developer.vuforia.com/forum/creating-ar-trackables/cant-download-one-my-trackable-due-processing-error )

I have test to replace the uniform black background, by a white uniform black background, and it obtains 2 stars (against 0 before). Why this rating difference between this 2 colors ?

Strange evaluation of an image by the Target Manager

June 6, 2013 - 9:29am #4

I checked the image you sent me.

The problem with the image is that the features are very sparse, i.e. non-uniformly distributed across the image area.

The empty black background in particular is the major source of the problem.

I would consider using an image where you can put the same content but not on top of a plain empty black background....

 

Strange evaluation of an image by the Target Manager

June 6, 2013 - 8:55am #3

Hello Alessandro,

 

Thanks for your answer ! I have send you the image by private message.

 

 

Strange evaluation of an image by the Target Manager

June 6, 2013 - 8:30am #2

Hi, send me the image via PM, and I'll have a look at it...

 

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