steve55's profile - activity

Thanks for the answer, that makes sense to me. so i guess the accuracy can only be maintained in the float array, and once the array is plotted in pixels on the screen there may be slight error in the pixels due to rounding. This doesn't seem like a problem as the calculations will be done from the array, not the plotted pixels. Thanks again for your help.

Hi

From the example of RotateRect in the documentation the vertices are stored in an array of Point2f which contains floating point values, the line function then draws with these values.

Mat image(200, 200, CV_8UC3, Scalar(0));
RotatedRect rRect = RotatedRect(Point2f(100,100), Size2f(100,50), 30);

Point2f vertices[4];
rRect.points(vertices);
for (int i = 0; i < 4; i++)
   line(image, vertices[i], vertices[(i+1)%4], Scalar(0,255,0));

Rect brect = rRect.boundingRect();
rectangle(image, brect, Scalar(255,0,0));

imshow("rectangles", image);
waitKey(0);

My question is why is the array created using Point2f? wouldn't it be better to use Point2i? as pixel coordinates cannot be faction numbers anyway.

Also would there be a performance penalty in using floating point instead of int?

Thanks

Steve

I was looking for a function that could possible accept a distance variable as an input (5 pixels, 10 pixels) when the function is called. Thanks for the advice, when you mention center point are you talking about an (x, y) coordinate? and do an euclidean distance between 2 sets of theses (x, y) coordinated?

Hi

Is there a function available that will indicate if a set of coordinates is within a proximity of another set of coordinates?

I have a straight line and i want to detect if that is close to another line's coordinates or the edge of a circle.

Thanks in advance

Steve

hi

I am new to using openCV and i have just started with the tutorials. I am using the Canny with HoughLinesP on a straight lines just for testing, when i run the tutorial code on a diagonal line i always get 5 4-element vector coordinates. I though i would only get 2 for a straight lines, all the coordinates pass through the line so its correct, i was just wondering why there were more that 2.

Thanks

Steve