Lidar Data: Visualization, Analysis, and Editing

Europa Challenge Materials

Sample Data Sets

Download, save, and unzip these three sample data files. You can then open and work with them in the Web World Wind application:

Europa Challenge Notes

This entry submission is based largely on the lidar visualization, analysis, and editing capabilities I have built in Java using NASA World Wind and Java OpenGL. An additional part of the challenge submission involved porting much of the basic loading, parsing, filtering, and rendering functionality into JavaScript using Web World Wind and WebGL. Certain limitations of JavaScript as well as the outdated version of the GLSL shading language available in WebGL prevent the full migration of the system’s capabilities to JavaScript, but I anticipate that that situation will improve, for example as newer versions of WebGL begin to embrace the more recent versions of GLSL that have been released over the past five years or so.

You see on the main project home page two pairs of links, one pair on the left and one on the right. The top link in each pair launches the Java version; the lower launches the JavaScript version. First let me briefly explain why there are two versions of each. To render a lidar file on a World Wind globe, we must know how to map the coordinates in the file to World Wind’s lat-lon-elevation. The LAS specification includes mechanisms for recording that information in the file, but many lidar files are created without that information actually being stored. Such files cannot be rendered in World Wind. The program links on the left run a standalone application that render the points of a lidar file using their native coordinates outside of World Wind. Hence it is capable of processing any lidar file. On the other hand, the links on the right render the lidar data on the World Wind globe, hence can only be used for files for which georeferencing information can be determined.

The pages on this web site document the usage of the full Java version. The portions that have been ported to JavaScript have analogous features, although the actual user interface looks a little different and does not yet have as rich of a set of rendering modes as does the Java version. As you explore the full site, you will see detailed instructions for operations, screen shots, editing and rendering strategies, and more.

I want to especially acknowledge the support I have received from the NASA World Wind development group – in particular, Tom Gaskins and Dave Collins – as well as the enthusiastic participation of a critical group of users from the City of Springfield, Oregon, most notably Brandt Melick and Chris Zeitner. The use of data they have provided as well as their ongoing encouragement and feedback have been central to the success of this effort.

Platform Notes

The full Java version runs on all current platforms (Mac, Windows, Linux).

The Web World Wind version has been extensively tested using Firefox and Google Chrome browsers on both Macintosh and Linux machines. The current Windows implementation of WebGL/GLSL apparently has a problem that prevents the GLSL program from linking.