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yes, no problem. Some minutes ago i asked something else about the radial distortion parameter K2, take a look at that if you can help me.

I'm doing some calibration for micro photogrammetry close range with a reflex (macro 60mm + extension 36mm maximum zoom) but I obtain always a value of K2 very big, from -100 to -500, even if not any particular distortion is evident in the photos. Any idea of the reason? In the opencv guide there's the explanation of the formulas behind the process of calibration where radial distortion coefficients are multiplied for "r", the distance between the point and the center, is that distance in pixels or mm?

good idea thank you.

yes, thank you for your answer, but i'd like to know if the accuracy on fx,fy,cx,cy is really to the 16th decimal place or not.

I'd like to know something about the accuracy of the calibration process, even if the results have several decimal places, i'm not sure that its accuracy is really that.

"code, please."

OpenCV Error: Bad argument (unknown array type) in cv::cvarrToMat, file C:\builds\2_4_PackSlave-win32-vc12-shared\opencv\modules\core\src\matrix.cpp, line 698

I tried to calibrate a camera with an asymmetric circle grid but none of the photos looked like recognized and after 5 or 6 photos running in the window "Image viewer" has appeared the error "OpenCV Error: Bad argument (Unknown array type) in cvarrToMat". Any idea on the problem? I'm using the .cpp file of "samples" folder of opencv downloadable here link text, the defaul.xml file i edited is this <?xml version="1.0"?> <opencv_storage> <Settings> <BoardSize_Width>13</BoardSize_Width> <BoardSize_Height>8</BoardSize_Height> <Square_Size>7</Square_Size> <Calibrate_Pattern>"ASYMMETRIC_CIRCLES_GRID"</Calibrate_Pattern> <Input>"C:/images/CameraCalibration/VID5.xml"</Input> <Input_FlipAroundHorizontalAxis>0</Input_FlipAroundHorizontalAxis> <Input_Delay>1</Input_Delay> <Calibrate_NrOfFrameToUse>25</Calibrate_NrOfFrameToUse> <Calibrate_FixAspectRatio>0</Calibrate_FixAspectRatio> <Calibrate_AssumeZeroTangentialDistortion>0</Calibrate_AssumeZeroTangentialDistortion> <Calibrate_FixPrincipalPointAtTheCenter>0</Calibrate_FixPrincipalPointAtTheCenter> <Write_outputFileName>"out_camera_data.xml"</Write_outputFileName> <Write_DetectedFeaturePoints>1</Write_DetectedFeaturePoints> <Write_extrinsicParameters>1</Write_extrinsicParameters> <Show_UndistortedImage>1</Show_UndistortedImage> </Settings> </opencv_storage>

scuse me I'm new in this forum

I'm trying to calibrate a camera using a symmetric circle grid with opencv. What does it specify In the output file the "nrOfFrames" parameter? Is it the number of photos where was clearly recognized the pattern? Does it mean that the other photos are useless?

Hi, i'm a novice in Opencv world, in the default.xml file to set the parameters for the calibration with a set of photos already acquired i set the number of raws and columns and the kind of pattern (symmetrical circle grid). I tried to change the "square size" but i noted no differencies. Is there a way to force the calcutor to acquire a photo with some missing parts of a raw of circles? Thanks for your help, forgive me for my bad english :)

Update (please answer or comment): What does it specify In the output file the "nrOfFrames" parameter? Is it the number of photos where was clearly recognized the pattern? Does it mean that the other photos are useless?