Re: [Therion] Turning LIDAR point clouds into cave maps

[kevin dixon]

Mix and match LIDAR and DistoX2 ?

You need to have something sufficiently large enough on your DistoX2
survey stations to register within your point cloud. Preferably at
least two points so that you can rotate the LIDAR point cloud(s) to
match the DistoX2 survey. Mine Surveys using ZEB or equivalent LIDAR
typically do a centreline survey using a theodolite and then add the
ZEB LIDAR clouds using Levelling Staffs at the Centreline survey
stations when doing the ZEB LIDAR survey.

The LIDAR survey can be decimated based upon distance to adjacent
nearest LIDAR points eg. choose a 0.3m point threshold or whatever you
think appropriate for your survey. The resulting manageable clouds can
then be rendered as local theodolite surveys (Range, Inclination,
Bearing) within the DistoX2 Survex/Therion survey, just make sure you
have sufficient registration points between traditional DistoX2 survey
and the LIDAR.

You can do a lot of DistoX2 splays and then try to manually match the
LIDAR point cloud to the DistoX2 splay model. This is the method I
used twelve years ago when I was first experimenting - it is very time
consuming. Now I would suggest you use something that is sufficiently
large enough to register in the LIDAR cloud that can be surveyed with
the DistoX2 eg. a large distinctive rock, formation or other natural
feature or something man-made, tackle bag, container, helmet etc.

There is also potential to use a photogrammetry model to bridge
between DistoX2 survey and LIDAR. Useful software packages to look at
include Meshlab and Meshroom.

Kevin Dixon
York

On Wed, 29 Nov 2023 at 14:09, Tarquin Wilton-Jones via Therion
 wrote:
>
> Hi Bill,
>
> > A few years ago Apple released a very high-end smartphone which has a
> > LIDAR feature (iPhone 12 Pro).  There are a few more models now which
> > have it.  I have heard of some people using this to create cave maps.
> > There is much I do not understand.
> >
> > Has anyone in the group taken the point cloud from an Apple LIDAR scan
> > and turned it into a Therion cave map?  If so, I am very interested in
> > the details of the process.
>
> OK, that's a mountain of a question. But yes they have been turned into
> maps, though I don't know about Therion.
>
> Firstly, iPhone can do LiDAR and photogrammetry at the same time, and
> you can put those together as a mesh with a tonne of post processing (it
> can even do colours because of the photogrammetry!). It can do some of
> this with its own software, but afaik, people prefer to use other
> software for the LiDAR processing. This can be used to create pretty
> accurate 3D views of caves. The loop closures look amazing, but it's
> hard to know whether the post processing is swallowing the errors. There
> is some work going on at the British Cave Surveying Group to get it
> working. Jono was pioneering this.
> https://3dcavesurveys.com
> https://www.youtube.com/@valaheritage-jonathanleste4205
>
> At the moment, it has no centreline (unless he added that since I last
> looked, but it's not a trivial task), so that currently makes it quite
> incompatible with Therion.
>
> It is also worth noting that the iPhone has a 10 metre range. With
> passages larger than that, it just invents a ceiling or wall, even
> though there isn't one, which can really confuse any software that wants
> to use the result. And no LiDAR scanner copes well with water.
>
> Secondly, with point cloud data, Julian Todd has a completely different
> surveying package used to draw up surveys. You draw them in 3D, using a
> VR headset. It's called TunnelVR. Some people love the experience, it
> feels a lot like a computer game. But it is extremely different from
> Therion - an entire world away, and although it can export paper
> drawings, it is not as mature as Therion in that respect. Julian is very
> enthusiastic about this if you wanted to ask for a demo.
>
> There are others who do post processing of LiDAR data, using white
> spheres placed in the cave to link the scans to each other. These rely
> on very expensive hardware (but this was used as part of the project to
> survey all the world's largest chambers). I am very poor with names, and
> forget who was doing that. Perhaps someone else can remind me.
>
> In all of these cases, a centreline does not exist. You could of course
> use a scanner at every station, and import those as splays. That is more
> data than I would ever want to work with in Therion. It would be
> impossible to see the positions of things like boulders, pitch lips,
> ceiling steps, etc., because the entire thing would be a mass of splay
> lines, and would just be a grey blob. Though you could draw the walls to
> perfection!
>
> Those should be good places to get you started.
>
> Cheers,
>
> Tarquin
> __

Re: [Therion] Bounding Box to big in Loch but fine in Aven

[kevin dixon]

Is there a 0,0,0 origin coordinate in one of your files ?
Are you using the same PROJ for all files ?

Kevin Dixon

On Fri, Sep 20, 2019 at 4:36 PM Max D  wrote:
>
> I have a somewhat big cave (2400 Stations) and since a few weeks Loch shows a 
> huge bounding box of obout 250x7500 km (!) see 
> http://filez.foxel.org/2c4512e8a235
>
> Export is done like this:
>
>  select m_all
>  export model -output output/windloch.lox
>  export model -format survex -output output/windloch-konstruktion.3d
>  export model -format compass -output output/windloch.plt
>  export model -format dxf -output output/windloch.dxf
>  export model -format kml -output output/windloch-konstruktion.kml
>
> survex Data is fine, PLT also (when viewed in Aven)
>
> lox and dxf have the huge bounding box
>
> kml seems to have only the surface survey and is missing the cave.
>
>
> So far I have not been able to poin down the change that caused it. Any 
> suggestions on how to hunt this error down?
>
> Regards
>
> --max
>
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Re: [Therion] Using 3d Scan Data To Create A Map

[kevin dixon]

I do not know.

I have in the past hand cranked a result by plotting LiDAR data 2D
(whole dataset or sub-slices) and manually selecting outer points to
create an outline or cross section but that was circa ten years ago.

An 'automated' approach will need some sort of fractal control -
coastline length problem.

Kevin

On Thu, Jun 20, 2019 at 6:56 PM Martin Sluka via Therion
 wrote:
>
> 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 :
> >
> > 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
> >  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 :
> >>
> >>> 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 :
> >>>>> 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.
> >>>&

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

[kevin dixon]

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
 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 :
>
> > 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 :
> >>> 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  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 
> >>>

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

[kevin dixon]

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  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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[Therion] World Magnetic Model

[kevin dixon via Therion]

The last Therion release 5.4.3 is dated 01 Feb 2019.

There has in recent years been a significant change of the Magnetic North
Pole location, less so for the Geomagnetic South Pole:
https://ngdc.noaa.gov/geomag/GeomagneticPoles.shtml

Given the above, an out of cycle World Geomagnetic Model WMM2015v2 was
released 04 Feb 2019.

When will this update appear in Survex and Therion ?

Thanks,

Kevin Dixon
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Re: [Therion] Lox model volume calculation

[kevin dixon via Therion]

Suggest you try CloudCompare and/or Meshlab.

There was a post on this subject:
https://therion.speleo.narkive.com/tyAS1f1D/export-to-3d-processing-softwares

MeshLab is prone to crashing and can be very frustrating but I have got
cave volume results from it.

Kevin

On Sat, Dec 15, 2018 at 6:01 PM chris pennos via Therion 
wrote:

> Anyone knows how to calculate the volume of a .lox model?
>
> Thanks in advance
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Re: [Therion] Fix station point using only 2D

[kevin dixon via Therion]

Adam,

Radio-location can give you depth but accuracy is not too good.
How have your surface positions at the entrance(s) and the radio location
been determined ?
Professional GNSS (~3cm), DGPS(~1m) or hand held (~3m) ?

I have radio-location fixes at the far end of a system to control any
accumulated azimuth bias.
For these I have assigned an elevation to the radio-location equivalent to
the cave survey at the radio location point and used an appropriate SD
value for the radio location data. You may have to iterate a few times and
experiment with SD values to see how it changes your survey with and
without the radio location fix(s).

Also better if you have radio location fixes at different points because
geology effects the position.
Use several in the survey - you should see how they fit (or not) - reject
the wildly out ones, adjusting to the rest will help reduce any bias.

150m is a lot of difference so I would be looking at the positional method
used, datum and grid, survey instrument calibrations, declination values
and then get additional radio locations to confirm. If you are dealing with
older survey data then you may want to consider a compass bias - does a
survey rotation significantly reduce the difference ?

Kevin Dixon

On Tue, Aug 21, 2018 at 10:41 AM, Adam Pyka via Therion 
wrote:

> Hi all,
>
> How to 'fix' the survey station point (to morph the cave plan) having
> only 2D coordinates?
>
> Using the radiolocation we get (with quite good accuracy) the station
> point position which is about 150m beyond the estimated location we
> get from surveying. So now I wanted to use this position to make a
> correction to the main polygon. But the 'fix' command need a 3D coords
> so how should I do that (no, there is no point to measure the depth by
> radiolocation by some reasons).
>
> Thanks in an advice,
> Adam
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[Therion] Surface Contours

[kevin dixon via Therion]

I have randomly distributed surface points from a Post Processed Kinematic
GPS survey (accuracy ~10cm) and wish to calculate surface contours. The
reason for doing this is to have detailed data for all the shakeholes.
Would like to import the contours into Survex/Therion so these can be seen
above the cave.

Has anyone else done this and how ?

My current thinking is to use the QGIS Contour tool to generate the
contours and then import these into Survex/Therion as elevation strings
using some intermediate data format yet to be decided.

Thanks,

Kevin
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Re: [Therion] 3D output file for printing

[kevin dixon via Therion]

3D Output
Suggest you use the open source Meshlab program for editing, converting
between 3D formats and point clouds.
I have done 3D crystal engraving using a sub-sampled point cloud. This is
particularly effective when lit by variable LED's but you will be limited
by the available crystal sizes. The laser creates micro-cracks in the
crystal at each data point. You have to experiment with the density of
point cloud, scale and offset it to fit inside your chosen crystal block
size using (0,0,0) for one corner or as per your engraver's requirements.
For 3D plastic output, find someone familiar with it who has a machine and
work with them. The main problems are small passages and having to use lots
of cutaway supports. You can subset the model based upon elevation and then
3D print each elevation range using a different colour plastic - helps with
model visualisation and display.
You can try fused powder deposition but this will give a solid form and
small passages will be fragile.
If you want realistic colour from 3D photogrammetry models then this is
possible by subsetting the 3D model and printing out small sections with no
overhangs plus added joints to aid assembly but the results are very time
consuming and not the best. Might be useful for a cutaway passage/chamber
display.
Kevin Dixon

On Wed, Jan 31, 2018 at 9:53 AM, Benedikt Hallinger via Therion <
therion@speleo.sk> wrote:

> Another option would be to engrave it into a glass block using laser. Has
> someone already done this?
>
> Am 2018-01-31 9:20, schrieb Martin Sluka via Therion:
>
>> Therion’s Loch viewer is able to export VTK file, which is compatible
>> with several 3D modeling programs and you may convert it to format for 3D
>> printing.
>>
>> Martin s.
>>
>> 31. 1. 2018 v 6:38, franck TUOT via Therion <therion@speleo.sk>:
>>>
>>> Hello,
>>>
>>> I was wondering if someone already tried to print some caves in 3D,
>>> using a 3D printer.
>>> Any input about how to get a .STL .OBJ .AMF or .3MF (which I know are 3D
>>> format for printer).
>>> If someone did a printing, any issue / success to share ?
>>> Like I guess any small narrow passage will be hard to print if the final
>>> print put some kind of pressure on it.
>>> Everything will depend of the scale obviously.
>>>
>>> Anyway, maybe it’s just a dream but I thought it’ll be possible to do
>>> such a thing those days : )
>>> Have a good evening everybody,
>>>
>>> Franck Tuot
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>>
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>
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[Therion] Turned through Angle Survey

[kevin dixon]

I requested Survex to be modified to have theodolite turned horizontal
angles but there have been other priorities.

I have input LIDAR data as Theodolite data into Survex by using the
horizontal circle readings as compass readings and then modify the compass
calibration value for each station LIDAR data only until the horizontal
angle matches the known or calculated magnetic compass reading between the
instrument setup station and the initial reference object. You can get some
very large compass calibration values. Theodolite vertical circle angle is
usually 0 at Zenith with horizontal readings at 90 and 270 depending upon
which face (Left or Right) the theodolite has been used to collect the
data. Use excel to create inclinometer values.

Appreciate that the above is not ideal and was very time consuming but it
allowed me to get the Gaping Gill LIDAR data into Survex.

Kevin



On Wed, Jun 10, 2015 at 2:26 PM, Markus Boldt 
wrote:

> Hi all,
> if you use a theodolite, you will have also an vertikal angle. So this is
> to calculate too. I would use Excel for the calculation - or not? To
> calculate the Data you have to write them in a table anyway.
> Greetings
> Markus
>
>
>
> -Ursprüngliche Nachricht-
> Von: therion-bounces at speleo.sk [mailto:therion-bounces at speleo.sk] Im
> Auftrag von Graham Mullan (External)
> Gesendet: Mittwoch, 10. Juni 2015 13:30
> An: therion at speleo.sk
> Betreff: [Therion] Turned through Angle Survey
>
> Martin
>
> I think Andrew is referring to a Total Station survey, though I presume
> that data from an old fashioned theodolite would look much the same. What
> he needs, I guess, is an automatic way of correcting (calibrating?) the
> horizontal angles with regard to North when the traverse is connected in to
> fixed points at either end.
>
> Graham
>
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[Therion] Therion Requests

[kevin dixon]

Colour by Altitude
Is it possible to colour by altitude along the wall edges only ?
I do not want the scrap filled with colour, just a colour edging along the
walls, either inside or outside and preferably able to define the colour
width. Perhaps add a feature to the colour fill function to allow the user
to specify complete fill or edge width plus inside/outside ?

Cross Sections
I have a major cave system in Survex with lots of splays that help define
cross sections and I am in the process of converting it all to Therion
again - was not happy with the first conversion due to my inexperience with
Therion.
Is it possible to create a cross section within Xtherion by selecting the
station and only the splays that define the cross section ?
That is, either the software automatically grabs the splays within a
certain threshold perpendicular to the centreline or the software allows
manual selection of which splays to use. My current method of manually
creating cross section data subsets is time consuming.

Thanks,

Kevin
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