[Therion] Using 3d Scan Data To Create A Map

[Martin Sluka]

Isn’t it as call for nuclear aircraft carrier to kill a fly?

Martin

Odesláno z iPhonu

20. 6. 2019 v 9:33, Pavel Herich <herich at speleodd.sk>:

> This software should do it:
> https://geoslam.com/hub/
> P.
> 
> 
> Dňa 2019-06-20 09:26 Martin Sluka via Therion napísal(a):
>> I’m curios if there is a software able to create  vector map outline
>> from cloud data automatically.
>> Martin
>> Odesláno z iPhonu
>> 19. 6. 2019 v 23:13, kevin dixon <geospatial3d at gmail.com>:
>>> Nick,
>>> I have both DistoX2 and LiDAR data for parts of the same cave.
>>> All the LiDAR scans were registered to create a single model as normal
>>> for LiDAR.
>>> The individual scans were then decimated in the Point Cloud Software
>>> using a suitable distance to nearest neighbour. I found Survex gets a
>>> bit overwhelmed with millions of LiDAR data so you may have to
>>> experiment with a suitable distance between adjacent LiDAR data. Each
>>> decimated individual scan was then output to LibreOffice Calc and new
>>> ranges, bearings and inclinations calculated to create single station
>>> Survex files with lots of splays, now all orientated the same way.
>>> Dummy traverse observations were created within Survex to link all the
>>> LiDAR scan stations based upon the Point Cloud registration
>>> coordinates and elevations of the scan stations.
>>> I then manually matched the Survex output of the above LiDAR data to
>>> some known DistoX2 observations or in your case, perhaps known show
>>> cave outline. You can do this within Survex by having your non-LiDAR
>>> data as another survey then using a Calibrate Compass figure (may
>>> require up to +/-180degrees) within the LiDAR Survex data to change
>>> the orientation so as to match the known and also setting one of the
>>> LiDAR stations within the Dummy traverse observations to coordinates
>>> and elevation that give a good fit with the known data. Several
>>> iterations are needed with these.
>>> Hope that is self explanatory.
>>> Has worked for me - I have a DistoX2 Survex model with very detailed
>>> LiDAR data in two large chambers - the resulting LOG file looks a bit
>>> weird eg.
>>>    1 8659-node.
>>>    1 19071-node.
>>>    1 21844-node.
>>>    1 22774-node.
>>>    1 23053-node.
>>>    1 24470-node.
>>>    1 25278-node.
>>> As a side note, part of my project includes a Show Cave and I have not
>>> had a problem with insitu metalwork there or on scaffolded sections of
>>> the cave. I have always kept the DistoX2 well away from metalwork and
>>> when the passage is narrow with metalwork, I have used an intermediate
>>> station with DistoX2 observations to it only, never from it.
>>> I have considered the use of turned angles to get through a serious
>>> metaliferous section - the Leica DST360 could do this for you or a
>>> small theodolite - use magnetic obs at each end to orientate it all.
>>> Kevin Dixon
>>>> On Wed, Jun 19, 2019 at 9:02 PM Nick Bairstow <Nick at pff.uk.com> wrote:
>>>> Hi, Something a bit different for the clever people out there.
>>>> I have been playing with some 3d scan data and have attempted to use it to create a Therion map.
>>>> Firstly we put created an outline of the cave passage using point cloud software and exported as dxf.
>>>> I turned the dxf into a background sketch and drew around it and could output a nice pdf of our cave. Also did a manual scaling. So far so good.
>>>> I added a dummy station and gave it entrance coordinates, then exported as a KML model. When I open the output file Google Earth fly’s to the correct spot and shows a pin with the cave name but no cave.
>>>> My question is , does this fail because we have no survey data, centreline etc and it is impossible to do this or am I missing something.
>>>> As an alternative I can export to an esri shp file and run that though Qgis and get what I want but as I am going to attempt to combine the 3 scan data with a several normal disto surveys I would like to see Therion Kml output work if possible to save lots of messing around. (GIS makes my head hurt)
>>>> On a side note using the point cloud software I can slice though the scan data on different planes and pick up lots of detail, rocks and boulders etc. Using the dxf/background image method I should be able to get a very accurate representation of the passage. I can hear you all saying what the hell is he doing that for when he could just survey the cave in the normal way! Well the cave is a show cave and absolutely rammed with metal walkways and cables. Disto tests showed wild inaccuracy’s so it was looking like the only viable option was going to be to use a Total Station device which we don’t have.  We then had a very kind offer to scan the cave, this has proved to be very interesting but drawing a normal map is a bit of a challenge although it seems not impossible.
>>>> Any help would be appreciated.
>>>> Nick
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