2018-11-15 09:30:50 -0500 received badge ● Popular Question (source) 2013-08-15 10:40:45 -0500 answered a question Algorithm Explanation Its obvious... In every program language I think its the same... Rewrite your question if you would say why this its divided by two. 2013-08-14 07:52:55 -0500 received badge ● Editor (source) 2013-08-14 06:39:49 -0500 asked a question How calculate and use FOV correctly Hi all, I'm new with OpenCV and a have a dude with calibrationMatrixValues. I want to calculate the maximum width and height that captures my WebCam to 50cm. I thought calculate using the FOV, for that I have calibrated the camera with a chessboard, as explained here: http://docs.opencv.org/doc/tutorials/calib3d/camera_calibration/camera_calibration.html#cameracalibrationopencv I invoke calibrationMatrixValues by passing the matrix ​​calculated. I don't know if this its correct FileStorage fs2("out_camera_data.xml", FileStorage::READ); Mat cameraMatrix2; fs2["Camera_Matrix"] >> cameraMatrix2; cv::Size imageSize(640,480); double apertureWidth = 1; double apertureHeight = 1; double fieldOfViewX; double fieldOfViewY; double focalLength; cv::Point2d principalPoint; double aspectRatio; cv::calibrationMatrixValues(cameraMatrix2, imageSize, apertureWidth, apertureHeight, fieldOfViewX, fieldOfViewY, focalLength, principalPoint, aspectRatio);  Whats the apertureWidth/height mean? Are they correct? When I run this, he tells me fovx = 44.68 and fovy = 34.26.These results would be corrects? I've been doing various tests and looking in different forums, and I can't understand. I try to get the values I need with these values and I do know if I'm wrong ( with my trigonometry calculations) or its because I call wrong the function. I should get out more or less about 60 cm of width Any help you can give me would be appreciated, Sorry for my bad english. A greeting.