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3D Laser Scanner System Uncertainty is Uncertain

In doing some work on an upcoming presentation to the TxDOT (Texas Dept. of Transportation SCOS (Standing Committee on Surveying) Conference yesterday I received a call from someone that is working on uncertainty. The two events are nicely linked in that the folks in Texas want to me to discuss accuracy standards. If only we had them.

The caller informed me that he is working on a methodology for determining the uncertainty of individual measurements made with a laser scanner. The idea would be to create an extension to the E57 data exchange format that would  support this new measurement uncertainty parameter. That would be a valuable step forward.

The basic applied research on laser scanner and LiDAR system accuracy is not being done. Vendors are still the only group that can calibrate their systems. The rest of us have to treat them like a black box. I guess if we are willing to accept that then all we can do is make multiple passes and see if the data lines up. Crude at best.

Your thoughts.

4 Comments

  • If the caller is working in medium range (2 to 150 metre) systems, they could join the discussion in the E57.02 working group on Medium Range standards to discuss how to make a standard for evaluating measurement uncertainty a reality. We are always looking for people who are keen to contribute to standards development for 3D imaging systems.

  • We have been working on uncertainty computation for a few years now, first in stereo photogrammetry, and then in LiDAR, especially full-waveform. More information on our AutoProbaDTM project website sites.google.com/site/autoprobadtm

    The idea is to use Bayesian inference to predict the error on the range measurement from each waveform, and then propagate the errors through the georeferencing and gridding processes, and finally to the final DEM. Currently, we provide an uncertainty map along with the DEM as an extra layer in GeoTIFF. It would be really interesting to be able to have a point cloud format that would allow us to store 3D uncertainty, for those who do not want a gridded product.

    André Jalobeanu
    UT Austin/ARL and NPS Monterey/RSC

  • Leica’s new P20 has a revolutionary check and adjust feature which allows owners/users to calibrate the system themselves, without relying on or sending it in to Leica. This doesn’t necessarilly speak to all the issued raised by the article, but it does speak truth to the statment, “Vendors are still the only group that can calibrate their systems.”

    Per Leica’s website:
    With “Check & Adjust” users can electronically check the accuracy of their instrument and adjust it themselves to ensure the highest level of performance, without having to send it to the factory or service center.

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