Re: CAD-Based Photogrammetry

From: <Gang>
Date: Sat Jun 18 2005 - 03:43:00 EDT

Fellow pipers,
Here is the nutshell information of the working of the LASERSCAN system, as gathered from the vendors of the software. The software (without naming any brand) is capable of capturing the cloud image of points, with the scanning of the laser camera, (shifted to different locations in succession in the plot), in the horizontal plane. It is obvious, the straight elements, like beams and horizontal pipe runs look curved, because of the angle based recording of the image by the camera. The bench-marks (A4 size papers) pasted on dominant locations in the plant, captured by the same camera, with known coordianates/grids provide the necessary dimensional database for the “north”ings and the “east”ings. The data taken in this way can be transferred to the data processor, who knows about the software.The software then interprets the information in the picture with the grid coordinates and helps rebuild the picture of the total plant with the AS SEEN details. A good amount of human interface also is required for achieving this result.
The reported claim is of plus minus 3 mm accuracy. It sounds quite promising, time will say.
Regards.
C. V. Gangadharan.

> This is most probably the solution to the "as-built
> problem".
>
> Not having had direct experience with this yet, I'd
> guess that it is
> expensive. Of course, "expensive" is relative; how
> much does a
> two-person team with a tape measure/Disto cost for a
> one-week site stay
> cost?
>
> With 8 megapixel cameras becoming more affordable,
> this could have a big
> impact on smaller and mid-sized piping facilities
> that plan on upgrading.
>
> "CAD-Based Photogrammetry for Reverse Engineering of
> Industrial
> Installations"
>
>

http://www.itc.nl/personal/vosselman/papers/tangelder2003.cacaie.pdf
>



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