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Issues with bottle label cylinder target and strange performance

April 24, 2014 - 12:24pm #9

We've created a test where a cylinder bottle label is being targeted. In order to properly create the cylinder target we had to add a lot of white space to the top and bottle of the image for the math to work out.

 

While, it is working great, and the label is recognized instantly - when a 3D object goes behind the real object, the tall cylinder target image is blocking the view of the 3D object behind it. Is there a way we can create the cylinder target without having to add so much white space on top and bottom?

 

Here are some images showing the issue.

 

http://cl.ly/image/153z2h2J0m1o

http://cl.ly/image/1d0s2E0U3y1N

 

Here is an image of the cylinder target we're using.

http://cl.ly/image/1E4424293y2S

 

 

Any help would be greatly appreciated!

 

Issues with bottle label cylinder target and strange performance

April 25, 2014 - 12:53pm #8

Hi,

I don't see the reason why you would need to create a target with such a large white border (top and bottom);

If I correctly interprete the images you attached, the label of the real bottle only covers a small part of it, so you could create a Cylinder Target whose height  corresponds to the actual height of the Label which wraps the bottle, and not the height of the entire bottle.

It seems that you are building a cylinder target whose height mathces the full bottle height, but this is not needed, since the Label is the only part which is actually used by Vuforia for tracking.

Have you considered this simple option ?

 

See also this section of the developer guide, which provides a lot of useful hints and explanations on these aspects:

https://developer.vuforia.com/resources/dev-guide/creating-cylinder-target

 

Issues with bottle label cylinder target and strange performance

April 25, 2014 - 12:59pm #7

See also attached image which illustrates visually what I meant in my previous message.

 

 

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Image icon cyl_target.png30.26 KB

Issues with bottle label cylinder target and strange performance

April 25, 2014 - 2:47pm #6

Yes we have reviewed the document and was using it as a guide. When uploading our target image, we repeatedly received errors due to the measurements that were being taken of the physical bottle. The label is an exact scan and we measured the physical bottle exactly. We were unable to get the target manager to accept our image unless we made it the way it is shown.

Issues with bottle label cylinder target and strange performance

April 26, 2014 - 5:45am #5

The label is an exact scan and we measured the physical bottle exactly

You should measure the unwrapped label (before or after scanning it, I guess you unwrapped it from the bottle)..

Suppose the label (without white borders at top / bottom) has these dimensions (just as an example):

- Label Height = 50 mm

- Label Length (i.e. the label rectangle width) = 314 mm

You should enter these numbers in the Target Manager:

- Side Length = 50

- Top Diameter = Bottom Diamater = 314 / PI = 100

(where PI ~= 3.14)

 

What are the actual dimensions that you are using for the label ? 

Do you have a scan JPEG or PNG of the label (without the additional white borders, just the core label)  that you could send me ?  

I could take a look.

 

 

Issues with bottle label cylinder target and strange performance

April 28, 2014 - 6:51am #4

The label is attached. The physicaly bottle measures 9in (228.6mm) in circumference and the label is 2in (50.8mm) tall.

 

-Matt

AttachmentSize
Image icon hires_label.jpg1.56 MB

Issues with bottle label cylinder target and strange performance

April 28, 2014 - 7:36am #3

Thanks for the image and the exact measures;

so, here is the issue:

  • your image (scan) size is: 3000 x 674 pixels   ==> the aspect ratio of your Label image is:  3000 / 674 = 4.45
  • your measures (228.6 x 50.8 mm) however indicate a different aspect ratio of you Label:   228.6 / 50.8 = 4.5

The different aspect ratio will make the Target Manager reject your image, when you try to upload it, as it is geometrically inconsistent with the real shape.

 

Now, it could be that your real measures are exact but the image (in pixels) is somewhat vertically stretched, or maybe missing some part (e.g. have you cut away some part of the original label when unwrapping it from the bottle ?)

Or, vice versa, it could be that your image scan is correct, but for some reasons your bottle measures are incorrect.

 

So, whichever is the error (real bottle measures or image scan), you need to make your image consistent with your expected dimensions, so that the aspect ratio matches (must be one of 4.5 or 4.45 for both the image and the real label)

 

For example, I was able to upload your image JPEG successfully, by correcting the dimensions as follows:

Your measured width:  228.6   ==>  Corrected Width:  =  50.8 (height) x 4.45 (instead of 4.5) = 226.06   (instead of 228.6)

Then I entered these values in the Target Manager:

- Height: 50.8

- Diameter = 226.06 / PI = 71.957

And this worked flawlessly, see attached image.

 

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Image icon Bottle_TargetManager.png161.68 KB

Issues with bottle label cylinder target and strange performance

April 28, 2014 - 8:04am #2

Your input has solved the issue we were having. I appreciate your help greatly! We're compiling another build and will report back if we have any other isses.

 

-Matt

Issues with bottle label cylinder target and strange performance

April 28, 2014 - 8:06am #1

You're welcome.

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