Big Bat Cave Fly Through made from the Armory LiDAR Data
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- čas přidán 3. 04. 2018
- Paige Wilson with QK4 Engineers has created an awesome fly through of the passage from the Armory towards the River Passage. It is just cool. The data was collected on Thanksgiving Weekend 2017.
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Nice
Very cool! Now I really regret not being able to take part.
We are funded for the Labor Day Weekend so there is another chance.
Not likely, trying to scrape enough $ together just to go to trail days and then Silver Dollar City with my granddaughters in July. Been takin on too many debts for others lately. Badass video though!
Why don't they use this tech with drones to explore supposed "dead ends" in caves to see if maybe a little grinding might open up more rooms in caves we havent fully explored?
Unfortunately the scanner needs to be on a tripod and have survey monuments (minimum three) to connect the scans. With new tech coming out then it may be possible. All of this stuff is pretty heavy and expensive so you have to have the people to carry it back into some pretty rough places. With grants, rented equipment and volunteers pushing the edges of exploration and the equipment doesn't always get on the list. Great question and would be a great project.
@@caverken so many rooms for us to explore… it’s very tempting. I hope the tech improves soon.
Happy splunking.
Thank you and Happy Splunking to you also
Hello! I am currently trying to implement a similar project with a photogrammetric overlay here in Germany. I am very interested in how the data was aquired and which specific LIDAR system was used?
Thank you for your interest. This is LiDAR data and not photogrammetry. It would be impossible to carry enough lights and batteries into Big Bat Cave to capture RGB data. With the LiDAR we could scan in darkness. We used Faro scanners. I will be glad to answer any questions. My email is in my about page.
@@caverken Thank you for your informative reply! You would be surprised how sensitive modern camera systems are and where there is a will there is always a way. It becomes a question of time. With modern top of the line cooled cameras it is theorhetically possible to image a section of cave just using photons flouresced from salts being excited by radioactive decay. This might take anywhere from a day to a week per section! however, depending on if a photomultiplier tube is used.
On a more realistic timescale, one can without problems use a conventional 360 degree array of high sensitivity astro cameras. I think a good led of 10 watts should produce circa 1000 lumen, giving a surface brightness of circa 10 lux in a sphere with a 3 meter radius, which is quite bright for these cameras and should enable at least exposure times of maybe 50-100ms or 20-10 FPS or so, you should be able to get a basic semi realtime photogrammetric measurement. How large are these cave systems typically and what is the albedo by the way? Are my numbers about right?
Lastly, how long does one usually stay down there for? A 2+KWh lipo or lithium ion battery should fit decently into a backpack enabling at least 200 hours of operation for the light, and maybe 100-150 hours at least with the camera systems, so based on this I would disagree about the light statement.
Thanks again for the information about the email!
@@ivanrodionov9724 I had to go get another cup of coffee before tackling this. Thank you for making me think. Lets start with the 3 meter light distance. In some areas of the cave we are < 10 cm from the walls and ceiling and other times we are 20+ meters from the ceiling. On long passages being able to space the LiDAR scanner 15+ meters between scans gets good quality data and moves the project through the cave. No one has ever measured the albedo since we are not dependent on light but the LiDAR does record the reflective indices. We used those numbers to create the gray scale in the video. We rent the equipment on a holiday weekend so we can get up to four days scanning for a day and a half rental fee. A group of four will scan for four hours and then be replaced that requires twenty four volunteers for a full day working around the clock. So we get three days for one day rental. Cavers usually spend with travel time eight to ten hours underground with travel time to the work site. We have three miles scanned and we will have to do overnighters in the cave to get more of the project scanned. We had a grant and caver support for that project but Covid hit and our cache of stored batteries and food turned to junk and had to be thrown away. Maybe next year. Thank you for the great discussion. I have an article in the NSS News (March 2017 Vol 75, Num 3) explaining the project. I can send you a copy if you let me know where.
@@caverken Intriguing! The question becomes what is the average distance to the wall in the caves? The problem with LIDAR grayscale values is that this reflection intensity is only measured in the infra red (or whatever wavelength band is used) and does not nesseserilly represent the true brightness visible to your eyes.
I think assuming a 30-50 percent albedo is fair for smooth ish shiny ish rock. I think 3 meters would make a fair average distance that will be a bit conservative actually. Even going by 10 meters radius as a worst case scenario, for the same reflected flux to the observer, an 11ish times increase in power is needed from a 3 meter distance case or circa 100-110 watts, which is still reasonable. Even at this brightness, the same battery pack can provide at least 20 hours of operation (100 watts is an insane light level by the way for an LED, comparable to a smaller sized football stadium light). At worst case scenario of 8-10 hours and at a worst case of 10 meter radius cave in all directions, you will have a margin of safety of 100+%, so incredibly safe in my opinion. Is there a proper margin of safety standard you use by the way? I try to aim for at least a 50 percent margin when working with critical systems.
Staying overnight in a cave sounds like a very interresting prospect.
If possible, I would be very interrested to read the NSS article. I'll check in your about if I can find the email, maybe you can send it to me there.
Where is this? would love to visit it
A good start would be to contact the Kentucky Karst Conservancy on Facebook. facebook.com/search/top?q=kentucky%20karst%20conservancy