OpenCV Q&A Forum - RSS feedhttp://answers.opencv.org/questions/OpenCV answersenCopyright <a href="http://www.opencv.org">OpenCV foundation</a>, 2012-2018.Thu, 05 Sep 2019 10:47:25 -0500Get Rotation and Translation Matrixhttp://answers.opencv.org/question/217954/get-rotation-and-translation-matrix/I'm programming one Asus Xtion depth camera, wich instead of an RGB image, it gives me the Depth information.
I already have the Camera and Distortion Matrices of the depth camera, but now, I want to calibrate the vision system, by getting the rotation and translation matrices.
I already have the 3D local coordinates of the points, from the camera perspective, but now I need to convert them to world/global coordinates. Since this camera has only depth information I was thinking: is it possible to calibrate this vision system by saying where is the ground plane? How shoul I proceed to put the blue plane as the ground plane of my vison system?
![image description](/upfiles/15676982772248991.jpg)
(note, in addition to the ground plane there's also an object on the plane)
I already tried using the solvePnP to get the rotation and translation matrices, but with no luck. Thanks in advance.dbots94Thu, 05 Sep 2019 10:47:25 -0500http://answers.opencv.org/question/217954/Determine relative 3d-position of camera to a rectangular plane.http://answers.opencv.org/question/207253/determine-relative-3d-position-of-camera-to-a-rectangular-plane/I have the following:
cameraMatrix (intrinsic parameters), distortionCoefficients, and 4 detected points of a Rect. In world coordinate system these 4 points all have z-coord of 0 (Rect lays on the ground). I know the proportion of the rect in world coordinates (width and height).
I know that homography can be used to relate pixel coordinates of same plane in two different images.
I want to generate depth information of camera in relation to this plane (maybe out of homographyMat ?). So some information like: cameraHeight above ground (resp. relative camera position to the plane) and the angle/angles between optical camera axis and axis perpendicular to the plane.
Is this possible?
LuisKThu, 17 Jan 2019 07:29:20 -0600http://answers.opencv.org/question/207253/Camera with auto-focus and 3D reconstructionhttp://answers.opencv.org/question/7278/camera-with-auto-focus-and-3d-reconstruction/Hi,
I'm using some very simple web cam, during the chessboard calibration I got every time very **different intrinsic matrix**(especially the part with focal lengths), is it because the camera has auto-focus? If I take the pictures of multiple chessboard position the undistorted image is afterward **more distorted then the original**, how can it be? Is it possible the auto-focus is disturb somehow the distortion parameters calculation? When I want to calculate projection matrix I need **non-variable focus length**, needn't I?
But I don't understand how such a camera can have auto-focus, when the there is need to screw the lens to make the picture sharp? I thought auto-focus is moving some lens to focus??
And second question is if I want to make a laser scanner. I need to somehow calculate the homography to laser plane is it right? So probably I can directly find the laser line on the chessboard during the calibration. But do I need to measure the distance of the chessboard or can I somehow calculate the distance from the chessboard? **Do I need chessboard 3D coordinates to calculate the extrinsic matrix**?
Thanks for your time
Regards
Martin
MartinTue, 12 Feb 2013 02:02:17 -0600http://answers.opencv.org/question/7278/