# 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. Hints (help_hints.htm)

# Hints for better scan results

These are general scanning hints about what you should and should not do. Some have been taken from our forum, so thanks to everyone who shared their experiences there!

### Important hints:

- Adjust your camera settings (aperture size, exposure time) and room brightness so that the camera image looks approximately like the ones in our online manual and in our example movies (download section). In the camera image, the laser line should be as thin as possible, but still a strong bright line. The rest of the image should be as dark as possible, even black, especially when you have neon light in your room (because it flickers).
- We really have obtained surprisingly good results with a cheap webcam (640*480 pixels, 20 Euro) and a cheap line laser (10 Euro). So before buying expensive equipment, try to improve your setup (room, background, camera settings, ...)
- If the object reflects the laser light onto itself (e.g. from the shoulder to the face of a bust), you must turn down the brightness (aperture size, exposure time...) so that these reflections are not or hardly visible in the camera image. Otherwise you will get faulty values there.
- Your camera should not use interlaced mode (DV cameras usually do) and should not use compression. Otherwise your results may be rather poor.
  If interlaced mode cannot be deactivated, you should move the laser as slowly as possible!
- If you want to scan a dark or transparent or reflective object, you should use e.g. baby powder to make it light-colored and matt.
- In the moment you press "Start", the laser should not be visible to the camera. From then on, the light condition in your room should not change anymore. If they change, press "Pause" and "Start" again.
- If you want to scan a living person's head, have him or her keep his/her eyes closed all the time during scanning! The shape of open and closed eyes are very similar.
  When you take a snapshot for the texture, the eyes can be open again.

### Further hints:

- Move the laser line rather slowly, and do not move the laser itself too much. It is better to move the laser line only once or twice but slowly over the object than several times with high speed. See our scan of the "angel" in the download section.
- Often, not all visible areas of the object can be scanned because the laser does not reach them from above. So after sweeping one or two times over the object from above, you should do another sweep from below the camera. See our scan of the "angel" in the download section. Note that this is only possible if the camera stands high enough above the table/floor.
- Scale the calibration pattern to the size of the model, such that the pattern AND the object fill the camera image sufficiently.
- Don't use glossy tape to affix the target to the corner. Don't use glossy material to make the corner. Glossy items near the scanning area will cause stray reflections of the laser.
- Adjust your camera position so that it can only see the background and the object you're trying to scan. The floor and the scene in the distance behind the corner should not be visible at all.
- Some lasers and cameras can be focused... make use of it, focus them to the object surface.
- A high camera resolution (more than 640*480) is only useful if your laser line is really thin on the object, your object has really small details, and the image noise is very low.
- When you scan a living persons's head, it is really important the he does not move his head. We found this not to be as easy as it sounds. It will help if he can lean his head against the background wall. Maybe it's a good idea to lie down, the head lying on the background corner, and scan from above.
- DAVID needs to see the laser line
  - on the left background plane in the left side of the image AND
  - on the right background plane in the right side of the image AND
  - on the object in the middle.
  So you do not need to hold the laser line exactly horizontally. Every line direction between 'horizontal' and 'diagonal' is OK.
  If your setup requires a rather vertical laser line, you should rotate the camera and the background by 90°. Then the floor or table can be used as one of the background walls.

# 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. Hints (help_hints.htm)