Camera Calibration Tutorial

1. Load the Tutorial

1. Start Blender.
2. Load the file tutorial.blend.

2. Examine the Scene

1. Layer 1 contains the geometry of the rendered scene.
2. Layer 2 contains Empties that comprise the calibration target, and a camera to calibrate.
3. Layer 3 contains the original camera and light source used to render the synthetic image.

3. Use the BlenderTsai.py Script

1. Use Alt-P in the text window to start the script. Note that while you're using the script, you will need to be able to view the 3D view in addition to the script window. The 3D window is used to select empties to use as calibration points.
   
2. Click the Load Image button and load the doc/calimg.tga image. This image is stored as a RAW TGA file because the script can only load RAW TGA files:

3. Select the Empty with the largest y-coordinate and x=0.  This empty corresponds to the top left corner of the checkerboard pattern. Move the mouse over to the script window and press SPACEBAR to add an image point.  You can zoom using the mouse scroll wheel or the zoom numeric button, and the image can be moved around by dragging with the middle mouse button. The cross-hairs show the point's prospective location. Click with the left mouse button to place the point:
   

4. If you need to move a point that has been placed already, you can invoke grab mode on it by pressing GKEY. You can select points using the right mouse button, and multiple selections can be achieved by holding down either SHIFT key. When working with the image points, GKEY, AKEY and XKEY work as expected. The only thing to note is that if you start a drag with GKEY, you must complete it; you cannot cancel by pressing ESCKEY. Points can additionally be deleted from the image by pressing the Delete button. Note that while the XKEY prompts before deleting points, the Delete button does not prompt.
5. Continue placing points on the image until each calibration Empty has a corresponding image point.
6. Select the camera to calibrate and click the Calibrate button in the script window (the default options are what you need - see below):

7. If everything has gone to planned, then the camera you have just calibrated will match (closely) the camera originally used to render the image. Check both the positions, orientations and the lens values of the two cameras.