LIDAR Analyst

Here is an article that talks about the stuff that I work on - software that aids in automated feature extraction from LIDAR data. (This is in addition to my work with Feature Analyst, which aids in automated feature extraction from EO imagery).

In his ILMF presentation on feature extraction from LiDAR data, Overwatch Textron Systems’ Chief Operating Officer Stuart Blundell observed, "Software development is always chasing after advances in sensor capability." He is dedicated to resolving the specific requirements of LiDAR in three areas that create bottlenecks during the feature extraction process:

• The use of multiple sensors during acquisition;
• The merging of RGB color data or intensity data with XYZ data points;
• High spatial resolutions and very large datasets.

Logjams result when the software chokes while trying to accommodate all of these characteristics of LiDAR. According to Blundell, they are most likely to occur at the data registration stage, during feature extraction, or when attributes are applied to the data so it can be useful in a GIS database. If LiDAR data can be manipulated in a way that aligns with GIS-ready vector or shapefile formats, mapping experts should be able to move beyond the mere visualization of a scene and into the extraction of smaller physical features from within that scene. See Figures 4 and 5.

  

Figure 4a - The first image shows a 7x7-kilometer tile of airborne LiDAR collected over Denver, Colo. The LiDAR data has been Hill Shaded using LiDAR Analyst software to support the visualization of the data. Higher elevations are in white colors and lower elevations in green.

Figure 4b - The second image shows the Bare Earth grid automatically extracted from the LiDAR using LiDAR Analyst. The Bare Earth is used to support terrain analysis.

Figure 4c (below) - The third image is the building footprints that are automatically extracted by LiDAR Analyst as 3D Shapefiles. LiDAR Analyst extracts simple, multi-component and complex 3D buildings from LiDAR. These 3D Shapefiles include 18 different geometric and descriptive attributes for each building such as maximum height above ground, roof type and area.

 

• LiDAR Analyst is an Overwatch Textron Systems software product designed in 2004 to provide this functionality as a plug-in for ArcGIS and ERDAS Imagine. It will be available in 2008 as a plug-in for Remote View and ELT.

Blundell also emphasizes the importance of file specification standards in software design, and lauds the work that has been completed in this area by the LiDAR Committee of the American Society for Photogrammetry and Remote Sensing. "If people are using LAS (LiDAR Data Exchange Format) standards for LiDAR, regardless of the size of the dataset, that’s standardized in a way that we can interpret information about the spatial resolution and that kind of thing," he says.

The LAS 1.0 specification already is widely accepted in the industry. An update, LAS 1.1, incorporated features that allowed for more robust point marking. LiDAR committee member Lewis Graham represents LAS 1.1 as an interim update that remedies problems in the 1.0 specification, such as limitations in the encoding of flight line numbers. He expects the LAS 2.0 standard to be a major revision, with accommodations for more comprehensive encoding of terrain modeling and for emerging technologies such as waveform digitization.

 
 
Figures 5a, 5b, 5c & 5d - This series from Overwatch Textron Systems shows feature extraction for identifying a dumpster.

Read the entire article at Imaging Notes Magazine - LiDAR Advances & Challenges