Blob group orientation
Mark Hastings from Australia  [3 posts]
7 years
I'm trying to make a setup that will recognise the orientation of a sticker that has two identical barcodes on it. Is there a way of linking two blobs such that the group is compared to a target that then shows what  the orientation of the part is?

My idea was to treat it as an "L" which is then on its side, back or inverted. I'm only interested in cardinal points NSEW, but so far have been unable to find a way that the target compare treats the two blobs as linked rather than two separate items.


Steven Gentner from United States  [1442 posts] 7 years

You could instead use the surround white area that encompasses the two bar codes ... but I think what you probably want is the label aligned for further comparison/reading? Try the attached which will replace the original label image with an image of JUST the label with 180 degree ambiguity (i.e. the image will either be right side up or up side down).

I used the Orient image to do the canonical orientation (i.e. orient the label to the same angle regardless of current orientation) before the blob_replace will remove the rest of the orientation. You can probably fiddle with it to get rid of the final 180 issue ... let me know if you need that.



Mark Hastings from Australia  [3 posts] 7 years
Thanks Steve I will have a look at that tomorrow at work.

The application is actually to recognize the orientation of the part (by using its label) as it is presented to the machine. Depending on this orientation defines what subsequent processing happens to the part.

I was thinking of making 4 different trained images to see if it will work better.

I've also tried to join the two barcode blobs but its not working well for me so far.

Early days as I'm a noob and just getting to grips with the myriad of options/filters

Steven Gentner from United States  [1442 posts] 7 years
In that case, you can probably extract just the label as was done in the last posted robofile and then use the ORIENT_IMAGE_ROTATION variable from the Orient Image module to know what orientation the original label is. Note, the angle that the Orient image rotates images to is dependent on the image being used and is largely undefined. The point is that it will rotate a similar image in a similar way each time. See the docs at


Mark Hastings from Australia  [3 posts] 7 years
Thanks I will look into that. I do have control over the label image so for now have added a black border to the label (easier to pickup when on a white background) and a nice big triangle in the white space between the barcodes to track orientation. This seems to be working very well so far and negates image variances in the other data on the label.

Thanks again for the pointers... much appreciated

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