Turning LIDAR point clouds into cave maps
Hello everyone - This is probably more of a general practices question than something specific to Therion. Among the group there is likely to be some experience with this. I hope at minimum someone can guide me to a place for further learning. 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. The biggest issue I see is this: How does the iPhone know where it is? There is no GPS in a cave. GPS is not accurate enough even if it did work. Inertial navigation also has big problems dealing with a cave environment. There are many other issues, but I think that is the big one. Thanks! -- =============== Bill Gee
On Wed, Nov 29, 2023 at 2:28 PM Bill Gee <bgee@campercaver.net> wrote:
Hello everyone -
This is probably more of a general practices question than something specific to Therion. Among the group there is likely to be some experience with this. I hope at minimum someone can guide me to a place for further learning.
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.
The model must be converted into a raster image, it can be processed.
The biggest issue I see is this: How does the iPhone know where it is?
The iPhone doesn't know, it doesn't use GPS for lidar. The model must be adjusted for surveying.
There is no GPS in a cave. GPS is not accurate enough even if it did work. Inertial navigation also has big problems dealing with a cave environment.
There are many other issues, but I think that is the big one.
Thanks!
-- =============== Bill Gee _______________________________________________ Therion mailing list Therion@speleo.sk https://mailman.speleo.sk/listinfo/therion
Balázs Holl
Hi everyone and Bill Same question as bill and quite interested as well to learn more about this techno and may be to test it as well.About the localisation I don't know yet how they can localise something in cave but for sure if you link lidar survey to each centerline point made by the DsitoX you can probably turnaround this issue witch is worthwhile if the lidar takes significant higher quantity of datas. David Le mercredi 29 novembre 2023 à 14:28:26 UTC+1, Bill Gee <bgee@campercaver.net> a écrit : Hello everyone - This is probably more of a general practices question than something specific to Therion. Among the group there is likely to be some experience with this. I hope at minimum someone can guide me to a place for further learning. 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. The biggest issue I see is this: How does the iPhone know where it is? There is no GPS in a cave. GPS is not accurate enough even if it did work. Inertial navigation also has big problems dealing with a cave environment. There are many other issues, but I think that is the big one. Thanks! -- =============== Bill Gee _______________________________________________ Therion mailing list Therion@speleo.sk https://mailman.speleo.sk/listinfo/therion
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
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 <therion@speleo.sk> 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 _______________________________________________ Therion mailing list Therion@speleo.sk https://mailman.speleo.sk/listinfo/therion
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.
I believe this purpose could very easily be served by the "three white orbs". (Though the accuracy might not be great, since they are not points, so you are hitting somewhere on a surface, and can't precisely locate that.) But this also then brings out the potential for error when the post processing doesn't match the centreline, and one of them has to "win". As you said, this is done in mine surveys. I still wouldn't want to be using Therion to draw up LiDAR data, just because there is so much that it becomes unusable. It is already hard enough drawing up a survey that has a lot of regular splays because the team got over-enthusiastic with the Disto. "Wait, which one of those splays points to the pitch edge?". And there is nothing to tell you if something is a pitch, a climb, a floor step, or a dangerous pile of loose boulders. Point clouds are great for showing fancy fly-throughs for non-cavers, and for mining engineers to see exactly how much more material they can remove before compromising a wall, but they add a lot of confusion for a cartographer. (But again, see Julian's project.)
A mountain of a question! That is for sure. I have been talking by email with a friend who claims to have done dozens of cave maps using the Apple LiDAR system. So far he has not gone into detail on how it was done. I asked for some samples of the maps he made. No Therion for him - he uses Xara and Compass. Update - While writing this, he sent me some sample files and a bit more detail. His description: "My process is create the "LIDARonly" version. Then layer on the cartography...then create the standard cave format...strip off the LIDAR (image without Lidar in the file name)." Looking at the sample files, it looks like he extracts some images from the point cloud. One of them is an overhead view and others are cross sections and profiles. He then uses these JPG images as the drawing background to produce a traditional cave map. The LiDAR scan essentially replaces the in-cave sketching. I suspect there is some custom software to extract the images from the point cloud. Another of my caving friends was doing photogrammetry over ten years ago. He used a regular digital camera and processed the photos through https://www.agisoft.com/ PhotoScan. It was amazing, and totally useless for cave survey except perhaps as a way to document formations. Yet another of my caving friends does survey in a slightly different way. In the cave he sets survey stations and records centerline data, just like everyone else does. But then he takes his GoPro and shoots a video of everything he just did. Later - out of the cave - he uses the centerline data and the GoPro video to make a traditional sketch. That is where Dennis stops. He does not go on to turn his sketch into a map. He hands it off to cartographers to take care of that. The stuff at 3DCaveSurveys is way cool - but it is not a cave map despite claims to the contrary. I found another web site which has a 3D visualization of a cave made with the Apple lidar system. https://www.tetongravity.com/story/gear-tech/digitalisation-of-caves-proceed... I downloaded the Torhola GLB file and was able to view it in MeshLab. Way cool stuff! He calls it a "model, not a map, and I agree with that nomenclature. I remember some years ago hearing about some mapping projects where the survey stations were marked with small balls in a specific color. The processing software recognized that color and provided a way to connect those points to known x,y,z locations - a centerline. It was fantastically expensive in both money and computer resources. In a way, we do sort of the same thing with Therion. The centerline data is processed to produce a set of x,y,z coordinates. The survey stations are flagged in that data set. Then when the sketch is drawn out, we insert points of type "survey station" which are also flagged. The sketch can be considered as a sort of two dimensional point cloud. Therion knows how to match up the survey station points in the sketch with the survey stations in the x,y,z coordinate set. From there it can morph everything around. So far the 3D presentations I have seen of caves would be useful auxiliary material for a cave map, but they are no substitute for traditional maps. =============== Bill Gee On 11/29/23 08:09, 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 _______________________________________________ Therion mailing list Therion@speleo.sk https://mailman.speleo.sk/listinfo/therion
On Wed, Nov 29, 2023 at 4:47 PM Bill Gee <bgee@campercaver.net> wrote:
Looking at the sample files, it looks like he extracts some images from the point cloud. One of them is an overhead view and others are cross sections and profiles. He then uses these JPG images as the drawing background to produce a traditional cave map. The LiDAR scan essentially replaces the in-cave sketching. I suspect there is some custom software to extract the images from the point cloud.
Indeed, the scans (combined with videogrammetry as in iPhone or iPad) preserve a lot of details and can be used to draw 2D maps. However, they can't completely replace the sketches or notes, as there is much information that can't be captured in the scans (air droughts, lake bottom etc.)
I remember some years ago hearing about some mapping projects where the survey stations were marked with small balls in a specific color. The processing software recognized that color and provided a way to connect those points to known x,y,z locations - a centerline. It was fantastically expensive in both money and computer resources.
In a way, we do sort of the same thing with Therion. The centerline data is processed to produce a set of x,y,z coordinates. The survey stations are flagged in that data set. Then when the sketch is drawn out, we insert points of type "survey station" which are also flagged. The sketch can be considered as a sort of two dimensional point cloud. Therion knows how to match up the survey station points in the sketch with the survey stations in the x,y,z coordinate set. From there it can morph everything around.
This is exactly the plan how to implement it in Therion, when time permits: 1) you scan a fragment of a cave (a 3D scrap) with some survey stations visually marked 2) you assign station names as used in Therion centreline to local 3D coordinates in the 3D scrap 3) Therion warps the 3D scrap and aligns it with the centreline 4) ideally, Therion smoothly joins adjacent 3D scraps The result would be a 3D model which could combine the walls captured from scans with those generated from the 2D scraps and LRUD data. This way you could progressively improve the 3D model as your LiDAR scanning progresses. There is a preliminary issue for this here: https://github.com/therion/therion/issues/475 Martin P.S. Here is a 50-metres dig scanned by an Apple LiDAR in around 30 minutes: https://photos.app.goo.gl/Cvs8mej2RCqpGoj9A
Hi guys, You can also view a 3D cave from a photogrammetric survey with caveview on Karst3D. Here is the link to the cave: https://data.oreme.org/karst3d/karst3d_map#selected_layer=karst3d_station&se... If you visualize the 3D lox file, this is a therion survey and if you visualize the 3D file (PLY), this is downgraded photogrammetric survey. You can easily project on a map the 3D point cloud and draw a map on it but in this case you have to work with a GIS software. The best would definitely be to have a code computing virtual survey stations to input it in therion, it could also be based on the trajectory of the camera used for the 3D photogrammetric model Cheers, Phil
On Nov 29, 2023, at 19:45, Martin Budaj <m.budaj@gmail.com> wrote:
On Wed, Nov 29, 2023 at 4:47 PM Bill Gee <bgee@campercaver.net> wrote:
Looking at the sample files, it looks like he extracts some images from the point cloud. One of them is an overhead view and others are cross sections and profiles. He then uses these JPG images as the drawing background to produce a traditional cave map. The LiDAR scan essentially replaces the in-cave sketching. I suspect there is some custom software to extract the images from the point cloud.
Indeed, the scans (combined with videogrammetry as in iPhone or iPad) preserve a lot of details and can be used to draw 2D maps. However, they can't completely replace the sketches or notes, as there is much information that can't be captured in the scans (air droughts, lake bottom etc.)
I remember some years ago hearing about some mapping projects where the survey stations were marked with small balls in a specific color. The processing software recognized that color and provided a way to connect those points to known x,y,z locations - a centerline. It was fantastically expensive in both money and computer resources.
In a way, we do sort of the same thing with Therion. The centerline data is processed to produce a set of x,y,z coordinates. The survey stations are flagged in that data set. Then when the sketch is drawn out, we insert points of type "survey station" which are also flagged. The sketch can be considered as a sort of two dimensional point cloud. Therion knows how to match up the survey station points in the sketch with the survey stations in the x,y,z coordinate set. From there it can morph everything around.
This is exactly the plan how to implement it in Therion, when time permits:
1) you scan a fragment of a cave (a 3D scrap) with some survey stations visually marked 2) you assign station names as used in Therion centreline to local 3D coordinates in the 3D scrap 3) Therion warps the 3D scrap and aligns it with the centreline 4) ideally, Therion smoothly joins adjacent 3D scraps
The result would be a 3D model which could combine the walls captured from scans with those generated from the 2D scraps and LRUD data. This way you could progressively improve the 3D model as your LiDAR scanning progresses.
There is a preliminary issue for this here: https://github.com/therion/therion/issues/475
Martin
P.S. Here is a 50-metres dig scanned by an Apple LiDAR in around 30 minutes: https://photos.app.goo.gl/Cvs8mej2RCqpGoj9A _______________________________________________ Therion mailing list Therion@speleo.sk https://mailman.speleo.sk/listinfo/therion
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.
As Tarquin said Jono Lester has been main UK pioneer on this. He may send a response. Julian Todd will say that you are asking the wrong question, and the right thing to do with a point cloud is use it to draw a 3D simplification rather than try to convert it to a traditional 2D simplification. His tunnelVR software lets you do this. Not everyone is convinced of this argument, but tunnelVR is well worth a look: https://sidequestvr.com/app/1630/tunnelvr https://www.youtube.com/watch?v=vOktKq0c7BY Wookey -- Principal hats: Debian, Wookware, ARM http://wookware.org/
If you can export your file as a las/laz file (or it also takes PolyCam's zip file of a laz file), then I have a place where you can preview it using the potree.org software. https://las.nix.how/ Try using the shortcode: c0987 to see a scan that was made underwater using photogrammetry. The potree software converts the pointcloud into streamed data, so it doesn't matter how massive your starting scan is as it only loads a limited amount. This is used as the starting point for tunnelvr, should you choose to use it for tracing up your scan into a 3D map representation. Julian. On Wed, 29 Nov 2023 at 13:28, Bill Gee <bgee@campercaver.net> wrote:
Hello everyone -
This is probably more of a general practices question than something specific to Therion. Among the group there is likely to be some experience with this. I hope at minimum someone can guide me to a place for further learning.
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.
The biggest issue I see is this: How does the iPhone know where it is? There is no GPS in a cave. GPS is not accurate enough even if it did work. Inertial navigation also has big problems dealing with a cave environment.
There are many other issues, but I think that is the big one.
Thanks!
-- =============== Bill Gee _______________________________________________ Therion mailing list Therion@speleo.sk https://mailman.speleo.sk/listinfo/therion
We have been experimenting with using the iphone's 3d sensors (it uses a combination of structured light and lidar for it's 3d sensing) in the lava tubes in Iceland and have found it to be vastly superior to using the disto alone. This is partially due to how strongly magnetic the lava is (magnetic anomalies of 10s of degrees are very common). In addition to the lidar and the structured light sensors, the iPhone uses its magnetic sensors and accelerometers, this helps it create an accurate model but does also cause some issues. While the addition of the accelerometers and 3d sensors do really help, the magnetic anomalies do still sometimes cause us some issues, the models tend to tear and become inaccurate when we encounter those. In tight passages it is also very easy to bump the phone against the floor or ceiling and due to the accelerometers this always messes up the map. To mediate this, we try to keep our scans to no more than 20 minutes at a time when surveying in difficult sections and stitch them together afterwards. This prevents us from having to repeat large and difficult scans, but does add some extra work at the computer. In addition to giving a much more detailed model of the cave than one would get with the disto the survey also goes much faster. We have easily halved the survey time in addition to removing much of the frustrations of the previous methods using the disto x (although it does introduce some new frustrations of its own). We have not experimented with creating maps in Therion from iphone generated 3d models. None of us has prior experience with working with 3d models so that alone has been a quite steep learning curve with still some way to go, and on top of that we have only limited experience using Therion, so that is another learning curve we have to scale. I have experimented with using Jari Arkko's cave-outliner ( https://github.com/jariarkko/cave-outliner) to generate outlines and cross-sections and used Inkscape to add details. Here is an example of a scan from a survey expedition last summer: https://poly.cam/capture/9A259EC8-3C88-446A-9023-0E589588821C - Can take up to a minute to load, so be patient. https://map.is/base/@419189,311927,z14,0 - Aerial photo of the cave's unique location within the main crater (shared freely online as the whole island is closed to the public and has a *very *strict access control, only allowing a single scientific exploration per year). This year's expedition was recorded and included in a documentary celebrating the islands 60 year anniversary. It is available online here (only available in Icelandic, sadly): https://www.ruv.is/sjonvarp/spila/surtsey/35251/ag5o1h - The cave section starts at 49:30 and the iPhone lidar can be seen in action at about 52:50 Best regards, Þórir Már On Mon, Dec 11, 2023 at 2:08 PM Julian Todd <julian@goatchurch.org.uk> wrote:
If you can export your file as a las/laz file (or it also takes PolyCam's zip file of a laz file), then I have a place where you can preview it using the potree.org software. https://las.nix.how/
Try using the shortcode: c0987 to see a scan that was made underwater using photogrammetry.
The potree software converts the pointcloud into streamed data, so it doesn't matter how massive your starting scan is as it only loads a limited amount.
This is used as the starting point for tunnelvr, should you choose to use it for tracing
up your scan into a 3D map representation.
Julian.
On Wed, 29 Nov 2023 at 13:28, Bill Gee <bgee@campercaver.net> wrote:
Hello everyone -
This is probably more of a general practices question than something specific to Therion. Among the group there is likely to be some experience with this. I hope at minimum someone can guide me to a place for further learning.
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.
The biggest issue I see is this: How does the iPhone know where it is? There is no GPS in a cave. GPS is not accurate enough even if it did work. Inertial navigation also has big problems dealing with a cave environment.
There are many other issues, but I think that is the big one.
Thanks!
-- =============== Bill Gee _______________________________________________ Therion mailing list Therion@speleo.sk https://mailman.speleo.sk/listinfo/therion
_______________________________________________ Therion mailing list Therion@speleo.sk https://mailman.speleo.sk/listinfo/therion
participants (10)
-
Balambér Hakapesz -
Bill Gee -
david Le berre -
Julian Todd -
kevin dixon -
Martin Budaj -
Philippe Vernant -
Tarquin Wilton-Jones -
Wookey -
Þórir Már Jónsson