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

Thu Jun 20 19:55:37 CEST 2019

Kevin, is any of those softwares able to create vector outline of projection of cloud to a plane?

Martin

> 20. 6. 2019 v 12:43, kevin dixon <geospatial3d at gmail.com>:
> 
> Those with their own LiDAR instrument will usually have access to
> their LiDAR manufacturer Software and this often includes automated
> rendering of man-made surfaces - results quality depend a lot on the
> LiDAR resolution and accuracy. Natural surfaces such as caves are more
> difficult for Point Cloud software to deal with automatically.
> 
> For the rest of us, you may wish to consider the following open source
> software for Point Clouds:
> MeshLab - lots of functionality, poor interface, I used this a decade
> ago when there were few open source options
> CloudCompare - nice interface, I have not used it for a while
> ParaView - uses PCL (Point Cloud Library), PCL can be used direct
> depending on your coding ability
> PDAL - a library of point cloud tools, need to use something like QGIS
> for results visualisation
> Blender - more for 3D videographics
> 3DTK - 3D Toolkit, not familiar with
> 
> Other options are available.
> 
> Kevin Dixon
> 
> On Thu, Jun 20, 2019 at 9:36 AM Martin Sluka via Therion
> <therion at speleo.sk> wrote:
>> 
>> 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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