Fiducial filtering
quitana from Germany  [20 posts]
9 years
Hi Steve (and RoboRealm Team),

is it possible to add the following fiducial filters:

x-rotation (as a variable already present)
y-rotation (as a variable already present)
size --> Decimal indication (It seems that the algorithm uses only integer sizes)
rectangularity (or something other shape features)

Background is, that i want to use apriory information (I know the x-rotation and y-rotation of some fiducials roughly and want to filer out false positives.)

Another question: What thresholding algorithm you use? Otsu? Is it possible to use adaptive local Filtering (to find better old and a little gray fiducials in front of black and white walls)

thank you very much for support.
Anonymous 9 years

X & Y rotation filter has been added.
Size has decimal number (variable was already but display was just integer).
The filters will also accept decimal numbers if you type it in.

We also added a contrast feature which can help to remove false positives.

We currently use adaptive thresholding so if should get gray fiducials. Perhaps you can post an image that we can review?

Also, performance and accuracy improvements were made.

2.29.3 has those changes.


quitana from Germany  [20 posts] 9 years
Hello Steve,

thank you very much. I will try the new Version on monday. Thank you for your offer to send you images for reviewing. If i catch any problem next week i will show you.

thanks again.
quitana from Germany  [20 posts] 9 years
Hi Steve,

i have just take a little look in the new Fiducial dialog. I immediately came to a question:

How can i do a x-and y rotation filters filter  like:

rotation near "zero".

That would be angles between 0 and 10 AND between 350 to 360 degrees. Can i do this with 2 (min/max) values? I think these values are normally AND-connected, isn't it? mmh. perhaps i have to think about it and try on monday. It's late now here in Germany ...

thank you.
Anonymous 9 years
Welcome to circular math ... use min 350  and max 10 and that should do it.

quitana from Germany  [20 posts] 9 years
Hi Steven,

I've tried things. Most of things run very good. I have the following questions/comments:

1) I started the fiducial algorithm for a test and the algorithm recognized for true a fiducial with a size of 3.13. If i enter 3.05  (or any other 3.xx) in the MIN flter size field, the algorithm filters out the fiducial?!?  If i try with comma --> 3,05 (german) he does'n filter out untill 4,0.

2) I have problems with some gray fiducials. So i asked you for the thresholding algorithm. What thresholding do you use inside the fiducial algoirthm? otsu or (local) adaptive?? If i use the local adaptive filter from RoboRealm before fiducial recognition all things run good. But it would be nice if i could control the parameters a) windows size and b) mean directly in the fiducial window, because I dont' want the computer to do the same things two times.

Background for need of control the two parameters is, that I want to deal with different views (same physical fiducials have different sizes in different views)

It is possible to control the to parameters directly?

Thanks for support,

Anonymous 9 years

1. Please download 2.29.6 and the size filter should be fixed.

2. We added a adaptive threshold size to the interface. That changes the window size. But I'd recommend posting a couple of the bad gray fiducials here for us to test just to make sure what the issue is and that the window size is actually the issue.

Let us know if you still have problems ....


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