* 3D-Backgroundstructure out of two [[detectionplane]]s the laser´s line is reflected from in a normal setup.
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Two exactly rightangled matt and light colored planes in vertical with two functions:
  - While [[calibration]], the [[calibpointspattern]] has to be fixed these planes. The planes are defined as the XY-plane (where Z is equal zero) right and ZY-plane (where X is equal zero)left. {{user_page:magweb:calibcorner.jpg|}}(In practice the position of the XZ-plane, where Y is equal Zero, isn´t important: It is 20mm below the lowest row of calibpoints. The origin of the 3D coordinatesystem is right there (20mm below) and the planes meet)
  - While scanning, both planes have to reflect the laserline. Out of the angle, the lines hit each other, David calculates the position of the laserlight-plane and the 3D data of the reflected beam of the object.
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Tips:
  * The [[calibpointspattern]] has to be fixed accurately. Both at the same heigth and exactly rightangled. Glue it laminar, not only tape it. Best is to use selfadhesive material for the printout.
  * You can remove the pattern for scanning.

  * The strength of the laserlight, reflected by the planes should be rather equal in amount to that reflected by the object (to ease the cam´s settings). So, if you want to scan darker objects, you have either to make your objects brighter (babypowder) or use darker material for the detectionplanes.

Note: There are some other ways to use DAVID-Laserscanner with different background- or even foregroundstructure. See:
[[Windowsetup]], [[negative Window]]