# Table of Contents

1. Welcome to DAVID (help_welcome.htm)
2. Camera Calibration (help_camera_calibration.htm)
3. 3D Laser Scanning (help_3d_scanning.htm)
4. Shap Fusion (help_shape_fusion.htm)
5. Frequently Asked Questions (help_faq.htm)
6. General Hints (help_hints.htm)

# 3D Laser Scanning

After calibrating the camera (see help_camera_calibration.htm) you can start scanning.
The following steps will guide you through the 3D laser scanning dialog of DAVID:

1. Place the object that you want to scan between the camera and the Calibration Corner (close to the Calibration Corner). It should be visible in the middle of the camera image. In the left and right third of the image, the Calibration Corner must be visible:
2. Switch on the laser and point it into the scene. Adjust the camera settings (aperture, exposure), the position of the laser, and the light conditions in your room so that the laser line is clearly and brightly visible in the image, while the rest of the image is as dark as possible:
   Furthermore, it is important to switch off all automatic image enhancements (like auto-exposure, auto-gain, auto-white-balance, ...) .
3. The light conditions in your room should not change too much from now on!
4. Switch OFF the laser (or at least do not let it point into the scene), then press "Start"!
5. Switch ON the laser, hold it in your hand and scan the object by "brushing" the laser line over the object:
6. Some very important hints:
   - The laser line MUST be visible on the Calibration Corner in the left and right part of the image, and on the object in the middle AT THE SAME TIME.
   - The distance between the camera and the laser plane (i.e. the triangulation angle) should be as large as possible for high precision. Otherwise, you will see a warning "INTERSECTION ANGLE TOO LOW".
   - Depending on your camera's exposure settings, you should not move the laser line too fast.
   - In the "Scan results" window, you can always see which parts of the object you have scanned, and where you should "brush over" again:
   The brightness of the pixels in this window is automatically adjusted; it represents the distance of the corresponding surface point from the camera! This distance will also be displayed in the "Scan results" window when you move the mouse over it (bottom of the window, "value", in mm).
   - You can scan as long and often over the object as you want. Theoretically, you can move your laser hand around as you wish, but practically, you may get better results if you try to keep it at the same position and just rotate the laser.
   - In most applications, you do not need to scan EVERY pixel (see following screenshot for a typically sufficient "Scan result"):
7. After scanning, in most cases, it is a good idea to use the Averaging and then the Interpolation filters by pressing the corresponding buttons once. The effect of these filters may not be apparent in the "Scan results" image, but they will be when you update the 3D view (see next step).
   You can "undo" all filter steps anytime, thus restoring the original scan data. You should do this especially if you are not yet satisfied with the result and want to continue scanning.
8. To see or update the scanned object in 3D, press the "Show 3D" button. In the 3D window, you can use the right mouse button to rotate the object. You can also use the left mouse button to move and the mouse wheel to zoom your view. Press F1 (while the 3D window is active) to get a comprehensive hot key list.
9. You can continue scanning anytime, or restart by pressing "Erase".
10. When you are satisfied, you can export the scanned data into an .OBJ-file by pressing the "Save Mesh" button. The Alias Wavefront OBJ format is a standard mesh format, which can be read by many 3d applications. The 3d vertex coordinates and triangle list (indexed face set) is stored as plain text file. (If you need a different file format, it is possible to convert the OBJ-file using other available freeware tools.)

# Table of Contents

1. Welcome to DAVID (help_welcome.htm)
2. Camera Calibration (help_camera_calibration.htm)
3. 3D Laser Scanning (help_3d_scanning.htm)
4. Shape Fusion (help_shape_fusion.htm)
5. Frequently Asked Questions (help_faq.htm)
6. General Hints (help_hints.htm)