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Unable to determine object's concavity in OpenCV
How to determine a Python variable's type?In Python, how do I determine if an object is iterable?Determine the type of an object?Why drawcontours in OpenCV doesn´t fill contours in the edge of the image?General contour detectionTriangle detection using OpenCVopenCV: cannot detect small shapes using findContoursOpenCV Convex Hull coordinatesOpenCV 3.4.0 video contours/arclength error(s)how to join nearby contours in a opencv motion detection
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I am attempting to detect convex pentagons in an image using OpenCV. I am using the following image:
I first find the contours in the image and then do this:
approx = cv2.approxPolyDP(c, 0.04 * perimeter, True)
isPentagon = len(approx) == 5
When I ran this on the image, I got this result:
This white part in the image is being detected. I thought that checking the concavity would solve it. Here is what I attempted:
isPentagon = len(approx) == 5 and cv2.isContourConvex(c)
However, for all the pentagons I tried, isContourConvex returned False. I am not sure why. I tried other images as well and the same happened. Variable c is the contour.
Is there a way to fix this? Maybe a better way to check if a polygon is regular?
python opencv object-detection
asked Mar 24 at 20:33
Nick SolonkoNick Solonko
294318
add a comment |
I am attempting to detect convex pentagons in an image using OpenCV. I am using the following image:
I first find the contours in the image and then do this:
approx = cv2.approxPolyDP(c, 0.04 * perimeter, True)
isPentagon = len(approx) == 5
When I ran this on the image, I got this result:
This white part in the image is being detected. I thought that checking the concavity would solve it. Here is what I attempted:
isPentagon = len(approx) == 5 and cv2.isContourConvex(c)
However, for all the pentagons I tried, isContourConvex returned False. I am not sure why. I tried other images as well and the same happened. Variable c is the contour.
Is there a way to fix this? Maybe a better way to check if a polygon is regular?
python opencv object-detection
asked Mar 24 at 20:33
Nick SolonkoNick Solonko
294318
add a comment |
I am attempting to detect convex pentagons in an image using OpenCV. I am using the following image:
I first find the contours in the image and then do this:
approx = cv2.approxPolyDP(c, 0.04 * perimeter, True)
isPentagon = len(approx) == 5
When I ran this on the image, I got this result:
This white part in the image is being detected. I thought that checking the concavity would solve it. Here is what I attempted:
isPentagon = len(approx) == 5 and cv2.isContourConvex(c)
However, for all the pentagons I tried, isContourConvex returned False. I am not sure why. I tried other images as well and the same happened. Variable c is the contour.
Is there a way to fix this? Maybe a better way to check if a polygon is regular?
python opencv object-detection
asked Mar 24 at 20:33
Nick SolonkoNick Solonko
294318
I am attempting to detect convex pentagons in an image using OpenCV. I am using the following image:
I first find the contours in the image and then do this:
approx = cv2.approxPolyDP(c, 0.04 * perimeter, True)
isPentagon = len(approx) == 5
When I ran this on the image, I got this result:
This white part in the image is being detected. I thought that checking the concavity would solve it. Here is what I attempted:
isPentagon = len(approx) == 5 and cv2.isContourConvex(c)
However, for all the pentagons I tried, isContourConvex returned False. I am not sure why. I tried other images as well and the same happened. Variable c is the contour.
Is there a way to fix this? Maybe a better way to check if a polygon is regular?
python opencv object-detection
python opencv object-detection
asked Mar 24 at 20:33
Nick SolonkoNick Solonko
294318
asked Mar 24 at 20:33
Nick SolonkoNick Solonko
294318
asked Mar 24 at 20:33
Nick SolonkoNick Solonko
294318
asked Mar 24 at 20:33
Nick SolonkoNick Solonko
294318
asked Mar 24 at 20:33
Nick SolonkoNick Solonko
294318
294318
add a comment |
add a comment |
1 Answer
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The issues was that I was passing in the original contour found by cv2.findContours into the cv2.isContourConvex. That original contour has a ton of points, some of which give the shape a concave characteristic.
To fix this, I had to call cv2.isContourConvex(approx). This would evaluate the approximation of the pentagon that has exactly five sides and five vertices. Although I would later draw the initial contour, evaluating the contourConvex function on the approximation yielded the correct result.
answered Mar 24 at 22:50
Nick SolonkoNick Solonko
294318
add a comment |
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The issues was that I was passing in the original contour found by cv2.findContours into the cv2.isContourConvex. That original contour has a ton of points, some of which give the shape a concave characteristic.
To fix this, I had to call cv2.isContourConvex(approx). This would evaluate the approximation of the pentagon that has exactly five sides and five vertices. Although I would later draw the initial contour, evaluating the contourConvex function on the approximation yielded the correct result.
answered Mar 24 at 22:50
Nick SolonkoNick Solonko
294318
add a comment |
The issues was that I was passing in the original contour found by cv2.findContours into the cv2.isContourConvex. That original contour has a ton of points, some of which give the shape a concave characteristic.
To fix this, I had to call cv2.isContourConvex(approx). This would evaluate the approximation of the pentagon that has exactly five sides and five vertices. Although I would later draw the initial contour, evaluating the contourConvex function on the approximation yielded the correct result.
answered Mar 24 at 22:50
Nick SolonkoNick Solonko
294318
add a comment |
The issues was that I was passing in the original contour found by cv2.findContours into the cv2.isContourConvex. That original contour has a ton of points, some of which give the shape a concave characteristic.
To fix this, I had to call cv2.isContourConvex(approx). This would evaluate the approximation of the pentagon that has exactly five sides and five vertices. Although I would later draw the initial contour, evaluating the contourConvex function on the approximation yielded the correct result.
answered Mar 24 at 22:50
Nick SolonkoNick Solonko
294318
The issues was that I was passing in the original contour found by cv2.findContours into the cv2.isContourConvex. That original contour has a ton of points, some of which give the shape a concave characteristic.
To fix this, I had to call cv2.isContourConvex(approx). This would evaluate the approximation of the pentagon that has exactly five sides and five vertices. Although I would later draw the initial contour, evaluating the contourConvex function on the approximation yielded the correct result.
answered Mar 24 at 22:50
Nick SolonkoNick Solonko
294318
answered Mar 24 at 22:50
Nick SolonkoNick Solonko
294318
answered Mar 24 at 22:50
Nick SolonkoNick Solonko
294318
answered Mar 24 at 22:50
Nick SolonkoNick Solonko
294318
294318
add a comment |
add a comment |
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