CvInvoke.MinAreaRect(contour) returns the wrong angle
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I have a contour of a number plate and I want to check if it's tilted or not. I used CvInvoke.MinAreaRect(contour) but it always returns the angle == -90 even when the plate is obviously tilted, you can see the contour I draw in the picture below.
Does anyone know what happened and solution for my problem?
Here is the code:
Image<Gray, byte> gray = new Image<Gray, byte>("2.PNG");
Image<Gray, byte> adaptive_threshold_img = gray.ThresholdAdaptive(new Gray(255), AdaptiveThresholdType.GaussianC, ThresholdType.BinaryInv, 11, new Gray(2));
VectorOfVectorOfPoint contours = new VectorOfVectorOfPoint();
Mat hier = new Mat();
CvInvoke.FindContours(adaptive_threshold_img, contours, hier, RetrType.Tree, ChainApproxMethod.ChainApproxSimple);
double max_area = 0;
VectorOfPoint max_contour = new VectorOfPoint();
for (int i = 0; i < contours.Size; i++)
{
double temp = CvInvoke.ContourArea(contours[i]);
if (temp > max_area)
{
max_area = temp;
max_contour = contours[i];
}
}
VectorOfVectorOfPoint contour_to_draw = new VectorOfVectorOfPoint(max_contour);
CvInvoke.DrawContours(gray, contour_to_draw, 0, new MCvScalar(255), 2);
CvInvoke.Imshow("plate", gray);
RotatedRect plate_feature = CvInvoke.MinAreaRect(max_contour);
CvInvoke.WaitKey();
CvInvoke.DestroyAllWindows();
c# emgucv contour angle
edited Nov 12 at 10:25
Rob
9921022
asked Nov 12 at 9:16
Ha Bom
360417
add a comment |
up vote
0
down vote
favorite
I have a contour of a number plate and I want to check if it's tilted or not. I used CvInvoke.MinAreaRect(contour) but it always returns the angle == -90 even when the plate is obviously tilted, you can see the contour I draw in the picture below.
Does anyone know what happened and solution for my problem?
Here is the code:
Image<Gray, byte> gray = new Image<Gray, byte>("2.PNG");
Image<Gray, byte> adaptive_threshold_img = gray.ThresholdAdaptive(new Gray(255), AdaptiveThresholdType.GaussianC, ThresholdType.BinaryInv, 11, new Gray(2));
VectorOfVectorOfPoint contours = new VectorOfVectorOfPoint();
Mat hier = new Mat();
CvInvoke.FindContours(adaptive_threshold_img, contours, hier, RetrType.Tree, ChainApproxMethod.ChainApproxSimple);
double max_area = 0;
VectorOfPoint max_contour = new VectorOfPoint();
for (int i = 0; i < contours.Size; i++)
{
double temp = CvInvoke.ContourArea(contours[i]);
if (temp > max_area)
{
max_area = temp;
max_contour = contours[i];
}
}
VectorOfVectorOfPoint contour_to_draw = new VectorOfVectorOfPoint(max_contour);
CvInvoke.DrawContours(gray, contour_to_draw, 0, new MCvScalar(255), 2);
CvInvoke.Imshow("plate", gray);
RotatedRect plate_feature = CvInvoke.MinAreaRect(max_contour);
CvInvoke.WaitKey();
CvInvoke.DestroyAllWindows();
c# emgucv contour angle
edited Nov 12 at 10:25
Rob
9921022
asked Nov 12 at 9:16
Ha Bom
360417
1
Please provide us with an Minimal, Complete, and Verifiable example of your code. It's impossible to say whether there's a problem in EmguCV (less likely) or your code (more likely).
– dymanoid
Nov 12 at 9:24
I've just updated the code.
– Ha Bom
Nov 12 at 9:41
add a comment |
up vote
0
down vote
favorite
up vote
0
down vote
favorite
I have a contour of a number plate and I want to check if it's tilted or not. I used CvInvoke.MinAreaRect(contour) but it always returns the angle == -90 even when the plate is obviously tilted, you can see the contour I draw in the picture below.
Does anyone know what happened and solution for my problem?
Here is the code:
Image<Gray, byte> gray = new Image<Gray, byte>("2.PNG");
Image<Gray, byte> adaptive_threshold_img = gray.ThresholdAdaptive(new Gray(255), AdaptiveThresholdType.GaussianC, ThresholdType.BinaryInv, 11, new Gray(2));
VectorOfVectorOfPoint contours = new VectorOfVectorOfPoint();
Mat hier = new Mat();
CvInvoke.FindContours(adaptive_threshold_img, contours, hier, RetrType.Tree, ChainApproxMethod.ChainApproxSimple);
double max_area = 0;
VectorOfPoint max_contour = new VectorOfPoint();
for (int i = 0; i < contours.Size; i++)
{
double temp = CvInvoke.ContourArea(contours[i]);
if (temp > max_area)
{
max_area = temp;
max_contour = contours[i];
}
}
VectorOfVectorOfPoint contour_to_draw = new VectorOfVectorOfPoint(max_contour);
CvInvoke.DrawContours(gray, contour_to_draw, 0, new MCvScalar(255), 2);
CvInvoke.Imshow("plate", gray);
RotatedRect plate_feature = CvInvoke.MinAreaRect(max_contour);
CvInvoke.WaitKey();
CvInvoke.DestroyAllWindows();
c# emgucv contour angle
edited Nov 12 at 10:25
Rob
9921022
asked Nov 12 at 9:16
Ha Bom
360417
I have a contour of a number plate and I want to check if it's tilted or not. I used CvInvoke.MinAreaRect(contour) but it always returns the angle == -90 even when the plate is obviously tilted, you can see the contour I draw in the picture below.
Does anyone know what happened and solution for my problem?
Here is the code:
Image<Gray, byte> gray = new Image<Gray, byte>("2.PNG");
Image<Gray, byte> adaptive_threshold_img = gray.ThresholdAdaptive(new Gray(255), AdaptiveThresholdType.GaussianC, ThresholdType.BinaryInv, 11, new Gray(2));
VectorOfVectorOfPoint contours = new VectorOfVectorOfPoint();
Mat hier = new Mat();
CvInvoke.FindContours(adaptive_threshold_img, contours, hier, RetrType.Tree, ChainApproxMethod.ChainApproxSimple);
double max_area = 0;
VectorOfPoint max_contour = new VectorOfPoint();
for (int i = 0; i < contours.Size; i++)
{
double temp = CvInvoke.ContourArea(contours[i]);
if (temp > max_area)
{
max_area = temp;
max_contour = contours[i];
}
}
VectorOfVectorOfPoint contour_to_draw = new VectorOfVectorOfPoint(max_contour);
CvInvoke.DrawContours(gray, contour_to_draw, 0, new MCvScalar(255), 2);
CvInvoke.Imshow("plate", gray);
RotatedRect plate_feature = CvInvoke.MinAreaRect(max_contour);
CvInvoke.WaitKey();
CvInvoke.DestroyAllWindows();
c# emgucv contour angle
c# emgucv contour angle
edited Nov 12 at 10:25
Rob
9921022
asked Nov 12 at 9:16
Ha Bom
360417
edited Nov 12 at 10:25
Rob
9921022
asked Nov 12 at 9:16
Ha Bom
360417
edited Nov 12 at 10:25
Rob
9921022
edited Nov 12 at 10:25
Rob
9921022
edited Nov 12 at 10:25
Rob
9921022
9921022
asked Nov 12 at 9:16
Ha Bom
360417
asked Nov 12 at 9:16
Ha Bom
360417
asked Nov 12 at 9:16
Ha Bom
360417
360417
1
Please provide us with an Minimal, Complete, and Verifiable example of your code. It's impossible to say whether there's a problem in EmguCV (less likely) or your code (more likely).
– dymanoid
Nov 12 at 9:24
I've just updated the code.
– Ha Bom
Nov 12 at 9:41
add a comment |
1
Please provide us with an Minimal, Complete, and Verifiable example of your code. It's impossible to say whether there's a problem in EmguCV (less likely) or your code (more likely).
– dymanoid
Nov 12 at 9:24
I've just updated the code.
– Ha Bom
Nov 12 at 9:41
1
1
Please provide us with an Minimal, Complete, and Verifiable example of your code. It's impossible to say whether there's a problem in EmguCV (less likely) or your code (more likely).
– dymanoid
Nov 12 at 9:24
Please provide us with an Minimal, Complete, and Verifiable example of your code. It's impossible to say whether there's a problem in EmguCV (less likely) or your code (more likely).
– dymanoid
Nov 12 at 9:24
I've just updated the code.
– Ha Bom
Nov 12 at 9:41
I've just updated the code.
– Ha Bom
Nov 12 at 9:41
add a comment |
1 Answer
1
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up vote
0
down vote
accepted
Try CvInvoke.threshold() instead of gray.ThresholdAdaptive(). Set proper threshold and you'll get better contour than before.
add a comment |
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Try CvInvoke.threshold() instead of gray.ThresholdAdaptive(). Set proper threshold and you'll get better contour than before.
add a comment |
up vote
0
down vote
accepted
Try CvInvoke.threshold() instead of gray.ThresholdAdaptive(). Set proper threshold and you'll get better contour than before.
add a comment |
up vote
0
down vote
accepted
up vote
0
down vote
accepted
Try CvInvoke.threshold() instead of gray.ThresholdAdaptive(). Set proper threshold and you'll get better contour than before.
Try CvInvoke.threshold() instead of gray.ThresholdAdaptive(). Set proper threshold and you'll get better contour than before.
answered Nov 17 at 1:33
user10665551
add a comment |
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1
Please provide us with an Minimal, Complete, and Verifiable example of your code. It's impossible to say whether there's a problem in EmguCV (less likely) or your code (more likely).
– dymanoid
Nov 12 at 9:24
I've just updated the code.
– Ha Bom
Nov 12 at 9:41