OpenTopography Blog

Information and discussion related to high-resolution LiDAR topography for the Earth sciences

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Posts from August 2009

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LiDAR-Specific Sessions at Fall AGU Meeting

Posted on Fri, August 28, 2009 by Chris Crosby in Meetings

There will be two sessions at the 2009 Fall American Geophysical Union (AGU) Meeting in San Francisco (December 14-18, 2009) specifically targeted at Earth science applications of LiDAR.

One session is focused on terrestrial LiDAR (TLS):

G17: Ground Based Geodetic Techniques and Science Applications
Conveners:  Gerald W Bawden- US Geological Survey, Benjamin Brooks - University of Hawaii, David Phillips - UNAVCO

Ground-based geodesy is a rapidly expanding and evolving technology and because of their portability, relative ease of use, long acquisition ranges, and sub-cm spatial resolution, tools such as terrestrial laser scanners (TLS) and/or ground-based radars (GBR) promise to expand our detailed understanding of the fundamental processes that drive a broad range of spatial (3D) and temporal (4D) science applications. This special session invites contributions that discuss both the technical aspects of the technology and process-based geoscience studies using ground-based geodetic tools such as, but not limited to, TLS and GBR. What are the strengths, weaknesses, and limitations of the technologies? How is the technology being used to address static and dynamic scientific problems? We envision contributions from many disciplines such as natural hazards, geomorphology, structural geology, glaciology, hydrology, snow science, biological science, tectonic, and volcanology.

while the other emphasizes airborne data:

G13: Airborne Geodetic Imaging: Advances in Instrumentation and Methods
Conveners:  William Eugene Carter - University of Florida, Ramesh L Shrestha - University of Florida, Mahta Moghaddam - University of Michigan

Modern airborne geodetic imaging sensors, including airborne laser swath mapping (ALSM), interferometric synthetic aperture radar (InSAR, UAV SAR), multi-band digital photography, and hyperspectral imaging make it possible to collect high resolution (few meters down to sub-meter scales) topographic data over areas of hundreds to thousands of square kilometers, in time periods of hours. The resolution of these geodetic images is sufficient for developing and testing theories pertaining to land surface processes, and are increasingly being used for such other applications as surface-water hydrology, bathymetric mapping, landscape ecology, mapping of wildlife habitats, and forestry research and management. The focus of this session will be on recent advances in geodetic imaging technologies and methods, and more specifically on advances in the state-of-the-art of the instrumentation, operating procedures, processing, and filtering of observations to achieve the highest resolution and accuracy. Also of interest will be presentations focusing on possible improvements to the information content that might be achieved by combining observations from different geodetic imaging sensors (particularly of different resolutions), and combining geodetic imaging data with other types of observations. Presentations reporting scientific results obtained using geodetic images will be welcome, but the emphasis should be on the geodetic aspects of the research as opposed to discoveries more appropriate for presentation in sessions organized under other disciplines.

The AGU abstract submission deadline is September 3rd, 2009, 23:59 EST

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Oregon Releases LiDAR Data and Map Series

Posted on Wed, August 26, 2009 by Chris Crosby in Data • News

This week the Oregon Department of Geology and Mineral Industries (DOGAMI) released a new digital map series and a new digital data series featuring LiDAR data collected in the Portland Metro area by the Oregon Lidar Consortium.  Details about the release are available in a press release [PDF] and on their new LiDAR Publications page.

The Lidar Imagery Series (LIS) publications are PDF format maps showing bare earth and first return ("highest hit” in DOGAMI parlance) surfaces.  20 ft contours are shown on the bare earth images while the “highest hit” surface has the vegetation colored by height.  Both maps are quite attractive and appear positioned to replace the iconic USGS 7.5 minute quad maps.  Each LIS quad map costs $30 and can be ordered on CD ROM.

Although the LIS maps are pretty, more exciting is the actual data that was used to generate the maps.  DOGAMI is releasing these data as Lidar Data Quadrangles (LDQ) where each quad includes bare earth, first return and intensity images of the data.  Unfortunately, these data are not available for direct download and instead must be ordered on DVD at a rate of $200 per 7.5 quad.  The good news is that DOGAMI has made the all point cloud data available for free via the NOAA Topographic Change Mapping site and therefore it is possible to access custom gridded products in addition to the point cloud data.

UPDATE (08/27/09 @ 12:40 PM):
I ran a few quick jobs on the NOAA Topographic Change site to extract some of the new DOGAMI LiDAR data.  Below is point cloud data for the Willamette River through downtown Portland, OR.  The bridge in the center of the image is the Burnside:

It appears there may be an intensity calibration issue with these data based on the fact that the intensity of the points in the distance in the image are significantly darker than those in the foreground - the intensity difference appears to be along a tile edge - here is another look :

UPDATE: Ian Madin at DOGAMI reports that this intensity difference is due to the fact that there were two different sensors in use during the survey: ”Some of our data was flown with an Optech and Leica sensor, and the intensity images from those overlap areas often show significant differences.  The Optech also produced noisier data which shows up in a slopeshade map of the same area”


2 meter first return DEM of the same data that I also generated via the NOAA site:

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LiDAR and the EarthScope Speaker Series

Posted on Tue, August 11, 2009 by Chris Crosby in News

OpenTopography team member Ramon Arrowsmith has been selected as a 2009-2010 EarthScope Speaker.  The EarthScope Speaker Series is part of the larger EarthScope Education and Outreach program and seeks to present the scientific results of EarthScope researchers to faculty and students in departmental seminars at colleges and universities. 


Ramon’s presentation is titled: High spatial resolution tectonic geomorphology of active fault zones of western North America

GeoEarthscope and related LiDAR topography efforts have illuminated thousands of kilometers of active fault traces at decimeter resolution. These new data provide a spectacular opportunity to characterize fault zone geometry, slip-rate variation over time, and the interaction of surface and tectonic processes in the development of tectonic landforms. Bridging the gap in measurements of lithospheric deformation-between the seconds to decades of earthquake seismology and geodesy, compared to the million-year time scale of geology and structural seismology-tectonic landforms and earthquake geology contribute information about the strain release at the 100 to 100,000 year time scale. These results include the slip distribution from recent earthquakes and the shapes and sizes of the semi-independently moving blocks that comprise major fault zones.

Funding for travel and lodging expenses for Speakers is provided by the National Science Foundation.  You can apply online to bring Ramon or other EarthScope Speakers to your institution.

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Comparison of ASTER GDEM to SRTM

Posted on Mon, August 03, 2009 by Chris Crosby in Data

The recently released ASTER Global Digital Elevation Map (GDEM) from NASA and Japan’s METI has been widely publicized on geospatial data blogs, email lists and in the mainstream media.  At 30 meter resolution, these data promise relatively high-resolution DEM coverage for most of the globe (coverage falls between 83N and 83S latitudes).  These data can be accessed either via NASA’s EOS archive or Japan’s Ground Data System

OpenTopography team member Ramon Arrowsmith has a preliminary comparison of the ASTER GDEM data with 90 m Shuttle Radar Topography Mission (SRTM) data on his blog.  Ramon notes that due to various artifacts and high-frequency noise, the GDEM data may not be as impressive as one would hope relative to the SRTM data.

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