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Ca HSR using drones for preliminary surveying

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Posted by Overmod on Saturday, March 17, 2018 9:39 PM

It might be an interesting finger exercise to deduce the characteristics of the system they used from the reported precision, recording time, and processing requirements mentioned in the story.  And perhaps then to assess whether the results will be as robust in practical utility as the specs appear to indicate...

There have been some interesting articles in magazines like Point of Beginning about high-speed semiautomated scanning from UAVs for various surveying purposes, at least some of which fuse the approach used to make phone touchscreens practical with some of the methods of capturing and retrieving features from 'big data'.  I also have to wonder if the current stage of HSR construction requires true high accuracy at this time (the purpose appears to be preliminary assessment of possible routes).  

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Posted by Anonymous on Saturday, March 17, 2018 3:26 PM

I think the accuracy cannot explained in few words. There are too many factors influencing it like type of drone, type of camera (resolution, lens), height of flight, terrain to name a few.

Depending on some of these factors one can determine the area one pixel on the camera chip represents. The accuracy can get as good as to  2-times the area horizontally and 3-times vertically.

That was a very shortend excerpt from this website: http://geoawesomeness.com/accurate-drone-survey-everything-need-know/

Regards, Volker

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Posted by Overmod on Saturday, March 17, 2018 1:12 PM

I suspect MC may have some more scathing comments on this than regarding pointcloud reliability.

i did not actually realize this was a PR flackery release until I got to that line about the 'powerful Microstation feature' that is actually the PERL way to maintain manpages.  Sure enough, it turns out to be written by a Bentley Systems guy and appears to be short on details such as resolving the pointcloud to be free of foliage or other transient effects -- something that yes, I think hovering-UAV data collection followed by good computer post could accomplish, but in ways and using tools that the author either doesn't know well or is being coy about for proprietary reasons.  Either way, the path of truth is ill-served.

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Ca HSR using drones for preliminary surveying
Posted by blue streak 1 on Saturday, March 17, 2018 12:31 PM

Question for MC.  How reliable is the method quoted in speeding up the survey work ?

https://www.railwayage.com/analytics/high-speed-mapping-high-speed-rail/?RAchannel=news

 

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