has anyone used findCirclesGrid? I have had no luck using it for a couple of patterns I tried which are pretty easy to detect. the return value is false
Links to images http://robocraft.ru/files/opencv/acircles_pattern.png http://cdn1.stuff4scrapbooking.com/catalog/product/cache/4/image/9df78eab33525d08d6e5fb8d27136e95/4/7/474765.jpg
Width Height must be the correct way around.
For the asymmetrical circle grid on the default target.png w=4 h=11
Not the other way around as printed on the sheet!
Yes, it is written in the format of a matrix size (the same format is used for a chessboard) and it is stated in the OpenCV documentation:
patternSize = Size(points_per_row, points_per_column)
So in this case it becomes patternSize = Size(4, 11).
Yeah, I agree, it is not very clear.
Yes, I'm using it with the asymmetric pattern a lot and it works on my images.
Note you have to specify a correct size of the pattern and its type (the first your pattern is asymmetric and the second is symmetric).
Hi, I use symmetrical circle grid with patternSize of 4 * 3, which are 4 points per row and 3 points per column. However the return value of the findHoles() defined in class CirclesGridFinder is always false. Therefore, the findCirclesGrid() can not find the circle center points with patternSize of 4*3. If I want to detect the circle in symmetrical circle grid with patternSize of 4 * 3, is there any way to solve this problem. Thanks.
This is a strange situation. Could you please send me an example of your images?
Yes, the images are shown here: http://answers.opencv.org/question/5130/is-there-something-wrong-with-circle-grid-with/ Thank you for your attention!
Have you tried with the actual circle grid image provided by opencv?
You can find it here for example:
http://docs.opencv.org/trunk/_downloads/acircles_pattern.png
I do not know of a svg version, sorry.
I know that this post is quite old, but I guess this might still be useful to some people. I just found a PDF version of the calibration pattern for different paper sizes:
Asked: Sep 13 '12
Seen: 17,306 times
Last updated: Oct 15 '12
See a related question with the answer: http://answers.opencv.org/question/3471/findcirclesgrid-not-working