DAVID 3.x User Manual Pages

1. Overview
2. Hardware Setup
3. Camera Calibration
4. 3D Laser Scanning
5. 3D Structured Light Scanning
6. Texturing
7. Shape Fusion

In the Camera Calibration menu you can setup and calibrate your camera. Calibration means that the software gets to know the exact location, view direction, focal length, lens distortion etc. of the camera, so it can use its images for precise measurement.

How and where to set up your object, camera, and calibration panels:

1. Choose a calibration pattern size which suits your object. The pattern should be at least a little higher than the object.
   Left: Calibration Pattern too small; Right: Calibration Pattern too big.
   Measure/read the scale length (printed at the side of the pattern) and enter the value into the “Calibr. Scale” field in the software.
   
   
2. Set up the calibration panels at a precise 90° angle, and place the object directly in the corner, as far back as possible, at a height so that it is centered in front of the calibration pattern.
   
   
3. Place the camera looking into the corner. Choose the camera in the “Source” list so you can see the live view. Use the Camera Format menu to set resolution and color format (hints: <link>), then use Camera Properties menus to set exposure, brightness, contrast etc. The most important setting, “Exposure”, can be set directly in DAVID's main window with the slider at the top.
   Set camera focus so the object is as sharp as possible. Switch OFF auto-focus, auto-exposure, auto-brightness, face tracking etc. See here <link> on detailed tipps for all those parameters.
   Place the camera so that it sees the object completely (the object should cover most of the image height) and the calibration patter at the left and right of the camera image.
   
   
   
4. Temporarily remove the object so it does not cover the calibration pattern.
   
   
5. Click “Calibrate”. If calibration fails, adjust the image settings (mainly brightness and contrast ) such that the markers get well visible, then try again.
   
   
6. Now your camera is calibrated. It must not be moved and zoom/focus must not be changed. Also the calibration panels must not be moved. Otherwise you should repeat calibration.

(You can check in the 3D scene whether the position and orientation of the camera is correct. Of course the size of the camera body cannot be known.)
Place your object back at its place, carefully not moving anything else. Depending on your setup, continue with “3D Laser Scanning” or “Structured Light”.