[Therion] new Therion 6.0.5
Francesco Serafin
francesco.serafin2 at gmail.com
Tue Feb 22 21:49:14 CET 2022
Hi Stacho,
Yes I have a minimal sample. Please find it attached in a .zip file.
You'll find the th and thcfg and all outputs I generated, plus some
screenshots saved from Paraview and Loch.
Looking at the wireframe in Paraview, I see those 'pyramid-like'
connections between stations and splays.
That's why I imagined that this was the method used by Loch to build the 3d
volumes from splay information.
I can see the intersecting pyramids in the loch visualizer too (I saved a
screenshot of this in the out folder).
It seems that the 3d model doesn't create a surface where the cave walls
would be. To obtain that, we should generate a surface that connects the
edge of two neighboring cross sections.
What one can try to do is to write an algorithm that joins splays with
splays and generates a tube-looking convex hull for every pair of stations.
This might give a more realistic-looking result.
I only know how to do this mathematica (that's the only programming
language I know), and this method works over there... but I,m using a
built-in ConvexHull function which is a bit of a black-box. Maybe something
similar could be encoded into Loch somehow?
Thank you
Best,
Francesco
On Tue, Feb 22, 2022 at 6:30 AM Stacho Mudrak <lists at group-s.sk> wrote:
> Hi Francesco,
>
> do you have some minimal sample, where these pyramids are created?
>
> It looks to me like a bug and I should investigate this issue. Normally -
> only a 3D envelope of splay shots from each station should be created.
> Splays from other stations should not be taken into consideration.
>
> Thanks, S.
>
> On Sun, 20 Feb 2022 at 23:07, Francesco Serafin <
> francesco.serafin2 at gmail.com> wrote:
>
>> Hi,
>>
>> Thank you for the very useful "volume statistics" tool!
>>
>> I was wondering: how is the volume computed in Loch?
>>
>> Looking at Loch-generated models in Paraview, it seems to me that Loch
>> creates the volumes by joining every station to the splays radiating from
>> the previous and next stations, creating a sequence of pyramid-like solids,
>> like in this schematics:
>> [image: image.png]
>> (black=centreline shots, dashed grey=splay shots).
>> Does each of these "pyramids" contribute to the total with its own volume?
>> With this method, the mesh would contain intersecting volumes. To
>> simplify, if we imagine a cone with apex at the stations, the cones
>> intersect:
>> [image: image.png]
>> How does the computation of the total volume deal with the intersections
>> of the cones?
>> Does it somehow avoid the double-counting coming from the intersecting
>> regions?
>>
>> Thank you,
>> Best,
>> Francesco
>>
>>
>>
>> On Sun, Feb 20, 2022 at 4:08 PM Tarquin Wilton-Jones via Therion <
>> therion at speleo.sk> wrote:
>>
>>> "added support for cave volume calculation (Tools → Survey statistics)"
>>>
>>> Awesome addition.
>>>
>>> Could someone maybe explain what the difference is between 3D and LRUD
>>> envelope?
>>> I get how 3D probably works based on the rendered 3D view of the cave.
>>> But how can the LRUD thing work when I only use splays instead of LRUD?
>>> Does it just pick some particular or average splay and use it as a LRUD
>>> measurement? The results are so vastly different. Sometimes much bigger
>>> (one of my simple caves) sometimes much smaller ( a pothole).
>>>
>>> _______________________________________________
>>> Therion mailing list
>>> Therion at speleo.sk
>>> https://mailman.speleo.sk/listinfo/therion
>>>
>> _______________________________________________
>> Therion mailing list
>> Therion at speleo.sk
>> https://mailman.speleo.sk/listinfo/therion
>>
> _______________________________________________
> Therion mailing list
> Therion at speleo.sk
> https://mailman.speleo.sk/listinfo/therion
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.speleo.sk/pipermail/therion/attachments/20220222/303338fa/attachment-0001.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image.png
Type: image/png
Size: 197722 bytes
Desc: not available
URL: <http://mailman.speleo.sk/pipermail/therion/attachments/20220222/303338fa/attachment-0002.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image.png
Type: image/png
Size: 53352 bytes
Desc: not available
URL: <http://mailman.speleo.sk/pipermail/therion/attachments/20220222/303338fa/attachment-0003.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Loch_volumes.zip
Type: application/x-zip-compressed
Size: 150054 bytes
Desc: not available
URL: <http://mailman.speleo.sk/pipermail/therion/attachments/20220222/303338fa/attachment-0001.bin>
More information about the Therion
mailing list