Creating Digital Elevation Models from Low Altitude Photographs

A free tutorial on creating Digital Elevation Models (DEMs) from Photosynth point clouds is now available online.  The tutorial focus on using mostly free and Open Source software to create detailed georeferenced 3D models from low altitude aerial photographs that have been processed in Structure from Motion (SfM) software like that found in Photosynth and Bundler.  Each step of the process is documented in text and illustrations. All of the datasets used and created during for the tutorual are provided for reference.

 

The tutorial is available here:  palentier.blogspot.com

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Moderator
Comment by Gary Mortimer on December 30, 2010 at 10:50am
The missing link ( no I mean its whats needed, not the links missing)
Comment by brakar on December 30, 2010 at 12:59pm
Great work, thanks for sharing your know-how!
Comment by Mark Willis on December 30, 2010 at 1:09pm

@Jørn, Thank you. Hopefully your software will make the process obsolete.

 

@gary I wouldn't be surprised if some links were missing... Considering all the typos I'm now noticing.

 

Comment by ionut on December 30, 2010 at 2:13pm
Mark:Do you know how SfM application works?Is it open source?How those points in the cloud are selected?
Comment by Russkel on December 30, 2010 at 6:42pm
I have tried using the open source software that uses the same algos as photosynth (who wants to upload all their photos just to get a point cloud?). There is ALOT of manual steps and messing about with files, so I hope to cook up a python script that does all the messing around for you. Although I was unable to manually replicate the sample point clouds from the sample images it must have been due to an error I made during one of the steps. As for making DEMs.. fantastic!
Comment by Mark Willis on January 1, 2011 at 8:15am

@ionut You can read about how the process works at http://photosynth.net/background.aspx .  There is open source software which creates similar results here: http://phototour.cs.washington.edu/bundler/

@kamu You're right, several of the steps can be streamlined with scripts.  As for your results, did you compare them with my reference files?

Comment by Russkel on January 1, 2011 at 8:29am
Mark, I was referring to the samples that are included with the open source equivalents of photosynth. I have not yet tried your documented method. Thanks for writing it up.

Moderator
Comment by John Church on January 1, 2011 at 9:19am

Hi Kamu and Mark,

If you'll "bundle" (LOL) sift, write an installer to get everything into usable paths and script a simple high level interface for this you'll get many more on-board. The way it sits currently, I think many are too shy to use the app.

Nice work so far on this and your other mapping hacks though!

Comment by Russkel on January 1, 2011 at 9:27am

Hi John,

Exactly my thinking. A good project idea that one. It would be good to get something going. The problem I have is that I have no aerial photographs to use (that I have taken) ;). We'll see what happens.

Comment by brakar on February 1, 2011 at 4:59pm

Mark,

I just have released a tool for AffineTransformation of 3D pointclouds, as a first part of the tools I am working on. As is, it might be a simpler/faster alternative to JAG3D.

The full announcement can be found here: http://uavmapping.com/index.php?p=1_6_PC-AffineTrans

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