# How do I determine a camera projection matrix?

#### BlueScreenOD

I'm an undergraduate computer-science student doing research in the field of computer vision, and one of the tasks I've been charged with is calibrating the camera on a robot.

I understand the basic principles at work: a vector in 3D world coordinates is transformed into homogeneous 2-space through the pinhole model, and camera calibration is supposed to find the parameters that created that transformation. However, I'm a little stumped on the actual application of these ideas.

I'm using the "Camera Calibration Toolbox for Matlab" (http://www.vision.caltech.edu/bouguetj/calib_doc/). I've successfully used the program to analyze a series of images and determined the intrinsic parameters, and I have a set of extrinsic parameters (one for each image I fed into the program); however, I can't figure out how to generate the matrix that transforms the pixel coordinates into real-world coordinates.

If someone could point me in the right direction and tell me where I can learn what I need to know, I would be greatly appreciative.

Related Linear and Abstract Algebra News on Phys.org

#### mikeph

From a theoretical point of view, I don't see how it is possible. If you are projecting a 3D image onto a 2D surface, how can you tell where along the missing dimension to place the information you collect? In other words, how do you get depth perception with only one eye?

### Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving