[Figures 13 & 14] Common flaws in scan data include holes, missing data (left), flipped normals and floating data. Cleaned up scan data (right).

Advantages of laser scanning include fast 3D data acquisition and no contact with the object. The physical prop does not need to have a surface hard enough to be digitized manually, so soft objects can easily be scanned. Because there is no contact, fragile models can be scanned as well. Laser scanners quickly sample a large number of points. Only the parts of the object that are in the line of sight of the scanner can be measured. Multiple scanner positions are required to cover the complete object. Sometimes laser scanners work in cooperation with part turntables that enable the part to be precisely moved instead of the scanner.

Because an optical device is making the final measurements, laser systems have a hard time on shiny objects that reflect a lot of light and dark objects that absorb a lot of light. Problem parts can be painted white or sprayed with a white powder to make them more visible to the laser.

Some laser scanners have large scanning heads that are rotated around an object, capturing all the surface data, geometry and textures in one pass. Some laser scanners utilize a turntable or similar device that moves the model in front of the digitizing head of the laser scanner. In the case of the turntable, the laser still needs to move vertically to capture the 3D sections of the object being rotated in front of the digitizing head. There are other configurations as well, but what they all have in common is that the laser is moved in some way relative to the object to capture 3D data.

As a modeler who is required to use data received from a laser scanner or from any other scanning facility, certain things need to have careful attention in order to get satisfactory data. The modeler must clearly define the expectations to the person operating the scanning equipment. The modeler needs to ensure that the data has no gaps or visible seams; that criteria needs to be clearly spelled out to the vendor. If the vendor needs to deliver texture maps as well as 3D data, that should be spelled out as well. The best way to define expectations is to put them in writing.

A studio on a limited budget may have some latitude when it comes to locating a scanning vendor. Normally, however, a studio should use a vendor that has a good reputation and has been used by many other clients. Although the equipment manufacturers that sell the scanners are quick to tell customers it is the equipment that creates the quality data, the truth is that the people operating the equipment are the ones creating the quality data. This is identical to the situation visual artists find themselves in every day. Every time a new tool is introduced to the digital production market, there is a claim that this new tool will automate the job of the digital artist. The fact is, the artist — not the equipment or the software — is the one creating the work. For this reason, the studio contracting out the scanning work needs to use the best people for the job, not necessarily the best equipment.

A modeler who is responsible for the collection and final use of 3D scan data represents the studio as a buyer. As a buyer, the modeler will be responsible for ensuring that the data is usable, as well as the following tasks:

• Inspecting the data received to ensure that no holes are in it. Check carefully for any gaps or seams in the surface of the data. Figure 13 shows problems at the fingers and the sides of the head.
• Turning all the display of the software that is being used for viewing the data so the polygons are single sided. The modeler should make sure that the entire surface of the model has the polygons all facing the same direction.
• Examining the wire frame (nonshaded view) of the data to see if there is floating data resting inside the exterior surface of the data.
• Examining the surface data to ensure that when merged scans in a single data set are used, two or more layers of data are not resting on top of each other. This causes many problems when the modeler is trying to use the data.