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COMMON QUESTIONS FOR DAVID SCANNER PART1

By February 4, 20163D SCANNING

COMMON QUESTIONS FOR DAVID SCANNER PART1

What can I scan?

Generally, all visible matte surfaces that do not move for at least a few seconds (scanning time).
DAVID can create 360° scans by combining single scans (views from different sides). The scans should overlap to make correct alignment easy.
DAVID captures the 3D surface as a triangle net (point cloud plus connecting triangles) at correct scale.
Textures can be recorded too (with the same camera, one more click) so you can get a colored model.
To get some impressions, please take a look at our User Gallery.

What scan sizes are possible?

DAVID is mainly used for objects between 30 mm and 500 mm. However the whole setup is scalable, and other sizes are possible if you adapt your hardware. Scan sizes larger than 2 meter will require special setups. You will need to calibrate the scanner for the given size, which requires a 90° calibration corner in about the same size as the object. It is possible to scan large objects by scanning smaller regions separately and combining them later.

Which surfaces can be scanned?

The surface must not be too shiny. Highly reflective, translucent or very dark surfaces must be covered with coating spray.

What about resolution and accuracy?

We highly recommend to use one of our complete scanner products, e.g. SLS-2 or SLS-3. Please take a look at their technical specs.

If you build your own scanner, everything depends very much on your hardware. Basically the resolution is one 3D vertex per camera pixel. So a 1 megapixel camera will give you up to 1 million 3d points / vertices. Example: Object size 100 mm, 1.3 megapixel camera –> resolution around 0.1 mm. The expected accuracy can be even better than the resolution because we use subpixel accuracy algorithms. However the hardware and calibration must be precise enough…

What is the basic scanning procedure?

  1. Setup: Scale the setup according to the object, i.e. place, align and focus the camera (and projector) depending on the scanned object size. Adjust exposure/brightness.
  2. Calibration: Place the 90° calibration corner at the object’s location (or similar). Then calibrate the camera (one click). In case of SL scanning, the camera and projector will be calibrated together with one click.
  3. Scanning: In case of SL, each scan requires one click. In case of laser scanning, the laser line has to be moved slowly over the object by hand. You can collect several scans from different sides of the object. They should overlap.
  4. Texturing: With one additional click (possibly also adjustment of light conditions or camera settings) a texture is grabbed with each scan.
  5. Alignment: One by one, the collected scans are aligned to each other. The user defines the order (which scans are neighbors). As long as the scans overlap sufficiently, the correct alignment is found automatically (no markers necessary).
    If you use our motorized turn-table, the DAVID software will collect and align all the scans around the object with one click.
  6. Fusion: When all scans are aligned, the Fusion (one click) computes one closed triangle mesh without overlappings (possibly textured.)

Do we need a dark room for scanning?

Generally darker is better. Direct sunlight is too bright. But some environment light is OK, you don’t need pitch black. It is most important that the environment light is CONSTANT during scanning, and the laser (or projector) must be clearly brighter in the camera image than everything else.

Can the data be used for 3D printing or milling?

Yes! Of course DAVID does not create a machine program that drives your printer/CNC, but usually these machines come with a software that can import 3D triangle meshes.
Usually they require a “water-tight” 3D model (a model which has no holes, so that “inside” and “outside” are clearly defined). DAVID’s single scans are not closed, but the last processing step in DAVID, the Fusion, can create water-tight models.

Can the data be used for measurements/comparison/analysis?

Yes! The Enterprise version of our DAVID software offers some measurement and mesh comparison functions. Also DAVID exports in standard 3D file formats (OBJ, STL, PLY) which 3rd party software can import for analysis. The 3D data are at absolute scale (usually in mm).

 SCANNED GALLERY

INSTALLATION VIDEO PART 1

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