Inspired Stone


January 25, 2011, 4:07 am
Filed under: Mountain | Tags:

I recently discovered that airborne lidar data is freely available for a handful of US locations. And one of those locations: Yosemite Valley. That’s right, as a climber, I couldn’t have been happier. Visualizing the data is not a simple task. Airborne lidar data is produced by flying a plane low over the region of interest with a laser scanning over the surface of the earth. At each spot that the laser reflects off the ground, the elevation and position of the ground is recorded. The result is huge collection of x,y,z points blanketing the earth. It takes special software to manage the lidar data, primarily because a laser scan can easily produce millions of points. One piece of the Yosemite Valley lidar data covers the area around El Capitan with about 8.6 million points.

Thankfully there is academic work being done on lidar data and analysis and the software that has been developed is also freely available. Coincidently, the Institute for Data Analysis and Visualization here at UC Davis, is one of the organizations working on this topic and I used their LidarViewer and VRUI to visualize the El Cap lidar data. In addition, LASTools, developed at the University of North Carolina, provide a number of useful software tools to inspect and manipulate the lidar data (which has the file ending .las, hence the name LASTools).

The result of all of this is a cool 3D model of El Capitan.

There are holes in the data which I think were caused by overhanging sections of rock where the airplane mounted laser was not able to reach. I should also point out, that although the surface looks continuous in some places, it is actually composed of discrete points (about 8.6 million of them). You can zoom in quite close and see that the points reveal the fine detail in the cliff.

This is a close up view of the Alcove and Footstool

This one shows Mammoth Terraces and the Half Dollar

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4 Comments so far
Leave a comment

so cool! great visuals and explanations!

Comment by NicoleD

LiDAR data is available for many US counties, summarized on the National LiDAR Dataset page on Wikipedia. And one of the best pages summarizing LiDAR mapping resources is at http://www.lidarbasemaps.org.

Comment by greg

Just a small correction: LAStools was created in my free time while I was a postdoc at UC Berkeley and a researcher at LLNL. They are just hosted at my UNC web space. As a long time lover of the Eastern Sierras (the reason i came to settle in the Bay Area) your post makes me very nostalgic. I have been deported by homeland security for an accidentally visa overstay and will not be able to visit my beloved mountain range for many years … )-:

Comment by Martin

FYI – these Yosemite lidar data can now be downloaded from OpenTopography here: http://opentopography.org/id/OTLAS.112011.26911.2

Comment by Chris




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