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 <n...@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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