Most people are familiar with 2D scanners, and few computers used for graphics are unconnected to one. What happens when you have a 3D object you need to work on in a 3D graphics or CAD/CAM program? You make some sketches and measurements and hit Form-Z, right? Well, not any more. 3D Scanners Ltd in London have developed a solution to this problem, and they can sell you a scanner or offer their '3DSource' Bureau service to help you get the results you want, without the fuss of a week's worth of serious modeling.Visual Magic visited the offices of 3D Scanners, where Sean Varney, the '3D Source' Bureau Manager, treated us to a scanner demonstration and a chat!
3D Scanners design their own hardware (laser scanners) and software to integrate into proprietary modeling and animation systems. Different productions and animation packages place different requirements on a 3D model. Have you noticed - the 3D model you buy from a library rarely seems to be exactly what you need! One of the major difficulties 3D Scanners had to face in developing their code was to provide tools to enable the 3D model to be created to precisely fulfill the purpose for which it is required.
During the visit, Sean demonstrated the scanner's portability when he brought out the two smallish cases which contained the laser scanner and the digitisizing arm. The digitizing arm was a Faro Bronze which clamps to a sturdy table. In standard form it can do point touch scanning by physically touching the subject, though on soft or fragile surfaces this can be undesirable. The arm can record a 1m x 1m x 0.75m subject without repositioning. However, by using datum balls (white spheres) on the object it can continually leapfrog around to cover larger objects.
The laser scanner we were shown was the top of the line model with a multi-power laser for scanning black/shiny objects and a camera for making colour texture maps. The laser is capable of scanning at an accuracy of 50 microns but not all projects would require this level of detail. Besides the control box which all parts plug in to, there is a footswitch for operation and a special DSP processor card to insert in the host computer.
The process is like painting with a 2 inch (50mm) wide paintbrush. The laser sensor is pointed at the object and the scanning starts. The sensor was held about 100mm from the object. It projects a 50mm long laser stripe onto the object. It can be angled in any way so that 100% of the surface of the object may be scanned. The scanned image appears on the computer monitor in real time. The image is shiny and looks just like wet paint! As the image is built up, any missed areas are obvious and can be rescanned (touched up) immediately.
The accuracy of the scanner is verfified by scanning a sphere of precisely known diameter. In this case, the difference between the actual and measured sphere diameters was 50 microns - about a hair's breadth.
The scanned data is stored as a collection of points (point cloud) measured over the surface of the object. On this particular scan the points were about 0.2mm apart. The digitizing process is fairly speedy. You can finish simple objects in a few minutes. A large, complex dinosaur model might take up to two hours so as to faithfully scan all the details such as teeth and wrinkles into the point cloud.
For a typical model about 30% of the time is spent scanning and the remaining 70% lies in the meshing of the point cloud data to create the desired model. For this task, 3D Scanners has developed a powerful and comprehensive suite of software algorithms running under NT 4.0.
The first stage of the meshing process is invariably the fusion of the point cloud to automatically produce a polygonal mesh of from 100,000 to 3 million polygons. Thats a lot of polys. But for some high-end film/broadcast applications, a half million polygon model is what is required. Reducing it to 10,000 polys can be accomplished automatically using the decimation (polygon reduction) tools. If you want a 200 polygon model for a real-time game, then 3D Scanners' remeshing software tools enable you to quickly draw a new mesh on top of the large mesh which acts as a template. Alternatively, if NURBS are required you can construct a number of polylines using sectioning and drawing tools. These polylines can be imported into your NURBS modelling package in which your NURBS are created.
A detailed description of the full 'ModelMaker' hardware and software system is beyond the scope of this review but more information on the technical specs and pricing can be found at 3D Scanners website - www.3dscanners.com.
Besides selling the hardware and software, 3D Scanners bureau called '3DSource' will also create custom models on a contract basis. Major customers include: REM Infographica in Spain, who use them for scanning models for their 3D model libraries; Codemasters, the UK games developer, where they scanned 3D models of the cars in their hit Christmas game: 'TOCA Touring Car Championship' and most recently for an in-house facility at Framestore in Soho.
Laser scanners and, perhaps more importantly, their accompanying model making software have undergone a long gestation. Now they have fulfilled their promise and are being used to produce high quality models by the market-leaders in 3D modelling and animation. And even for smaller projects, the 3D Source bureau service can save significant time and money.