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Author Topic: Photosynth -> Photoscan: cave sample  (Read 7056 times)

bigben

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Photosynth -> Photoscan: cave sample
« on: February 09, 2015, 10:54:14 PM »
I was asked about shooting in caves, with a Photosynth link provided as an example: https://photosynth.net/preview/view/d287952a-4e86-43c3-8d39-f08527508d7b

I had a play with the images in Photoscan and thought I'd share the results as I found them very interesting.  I ran a shadows/highlight adjustment on the images in Photoshop first, boosting the shadows 50% with a 50% range

Medium alignment and dense cloud
« Last Edit: February 09, 2015, 10:55:46 PM by bigben »

Geophotologist

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Re: Photosynth -> Photoscan: cave sample
« Reply #1 on: February 15, 2015, 10:46:55 AM »
Nice example. I have experience constructing tunnels in 3d and find it challenging but very rewarding. I too have to adjust tones in photoshop to help the program reconstruct the tunnel. What is the purpose to conduct cave photogrammetry?

nadar

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Re: Photosynth -> Photoscan: cave sample
« Reply #2 on: February 15, 2015, 12:37:29 PM »
very interesting
how many photos are involved ? What is the resolution ? Did you use a single flash light or an array of slave units ?

bigben

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Re: Photosynth -> Photoscan: cave sample
« Reply #3 on: February 16, 2015, 05:48:28 AM »
I never bothered to ask why... just seemed like a cool application ;)

I didn't shoot the photosynth. I just pulled the images from the project to get a feel for the problems/challenges for doing this.  I had another go with this one: https://photosynth.net/preview/view/e35f3cb4-bdff-44e1-9a8d-cc3bccb13a7b (200 images, 20mp)  I liked the use of a person for scale at intervals and they did a pretty good job of standing still. Haven't produced a model but the point cloud is 150M points at high quality. Pretty good result for something that probably wasn't shot for this specific purpose.

Would be interesting to see how something like a Samsung NX500 with a 10mm lens  (or Sigma 4.5mm circular fisheye) would go in this situation

KariH

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Re: Photosynth -> Photoscan: cave sample
« Reply #4 on: March 20, 2015, 10:54:30 AM »
Hi,

has anyone of you tried to model an underwater cave or mine tunnel with PhotoScan?
Here is our first test of that (low res version):

https://www.dropbox.com/s/isa66w1ftzoeze2/Virtual%20Mario.mp4?dl=0

It is a short "virtual dive" in Ojamo mine, a former limestone mine in Southern Finland.

A video was taken with a GoPro4 attached to the nose of a underwater scooter and a 2 hour dive was done mostly in 40-60m depth ( water temp 0....+4C.....).

The PhotoScan model was taken to Unity and a short virtual dive was generated there.


It will be interesting to test if this method could be used for cave documentation  (with more or less exact coordinates).

Kari

Jack_in_CO

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Re: Photosynth -> Photoscan: cave sample
« Reply #5 on: March 20, 2015, 07:43:28 PM »
I'm working on images that were taken in a cave to document fossils. Though I'm not trying to capture the entirety of a passage. There is a paucity of information or publications on doing in-cave photogrammetry for any reason. Pretty much a new frontier as far as I can tell.

 I used an array (3) of 1500 lumen LED work lights (rechargable/cordless), with a Nikon D800 and I'm getting pretty good results even with hand-held shots. Using 4 lights would have improved the results I think. Adding a tripod and you likely could do passage-wide modeling. Still, post processing was required - Some photoshop work to even out and increase the exposure on the raw image files. Will be presenting at a conference soon too on this effort.

bigben

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Re: Photosynth -> Photoscan: cave sample
« Reply #6 on: March 21, 2015, 03:05:22 AM »
If I was going to do this sort of thing I'd angle the cameras more towards the walls  and full frame fisheye... shorter distances for lighting, less fall off.  The samples I used above would have been awesome if they kept photographing on the way out to get the back surfaces.