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

[Martin Sluka]

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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