A Portal to High-Resolution Topography Data and Tools
As we announced last week, lidar data for the whole Lake Tahoe basin are now available via OpenTopography. Over the past week this dataset has seen a quite a bit of traffic, with over 160 jobs run (10+ billion points processed) by more than 50 unique users. However, our experience indicates that a large number of people just want to look at these data, and processing point cloud data to DEMs is clearly not the most efficient way to go about this. So, as I’ve done in the past for many of the larger datasets OpenTopography hosts, I ran the whole Tahoe Basin dataset through a routine to generate lidar derived imagery (hillshades and “slopeshade” images) that can be viewed in Google Earth. The resulting KMZ file can now be downloaded via our Lidar Derived Imagery in Google Earth page.
The file provides access to four layers of imagery, all at half meter pixel resolution: 45 and 315 degree sun angle hillshades of the hydro enforced bare earth grid, a slopeshade of the hydro bare earth grid, and a 315 degree sun angle hillshade of the highest hit (vegetation, buildings etc) surface. See images below for an illustration of the four imagery layers.
Once you download and open the KMZ file in Google Earth, the imagery is streamed from OpenTopography servers at San Diego Supercomputer Center to the Google Earth client for viewing. This is a large dataset (~14 GB of imagery) so initial display of the imagery can be sluggish, especially if your internet connection is not great. As you browse the data Google Earth fills its cache, and browsing speeds should pick up.
This set of imagery took somewhere in the neighborhood of 96 hours of time on my workstation to generate. But it is an excellent method for reducing an otherwise massive dataset down to something that is relatively easy for anyone with a computer, a network connection and Google Earth to access:
So, through this approach a 325 GB dataset is reduced to something small enough to be delivered dynamically across the network to users with a widely available, free, and familiar and intuitive client. It is important to note that the Google Earth imagery layers are not meant to be a substitute for going back to the actual elevation data to perform your scientific analysis; but for initial synoptic browsing, site selection, and education and outreach applications it is hard to beat the Google Earth approach.
Check out the images below, download the Tahoe Lidar Imagery KMZ file, and enjoy these amazing data.
But when viewed in the slopeshade lidar imagery, the trail is visible contouring 1600 feet above the lake shoreline clear as day:
For more information about the Lake Tahoe Basin Lidar Dataset, please see the initial OpenTopography news item HERE
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One of my favorite features in Google Maps is the terrain layer, which provides a shaded relief (aka hillshade) view of the topography derived from a digital elevation model. Google has done a nice job generating a visually pleasing terrain layer, and we use it for all of our Google Maps-based interfaces in OpenTopography. Google appears to use a range of digital elevation model data sources to derive the terrain layer. Throughout the US, it appears that the terrain layer comes from either 10 or 30 m (1/3 arc-second & 1 arc-second respectively) DEMs from the USGS National Elevation Dataset (NED). Globally the terrain data appear to be derived from either Shuttle Radar Topography Mission (SRTM) data or something like the NOAA Global Land One-km Base Elevation Project (GLOBE) dataset. Recently however, I’ve begun to notice higher resolution data in the Google Maps terrain layer. These higher-resolution data are localized, and are patched into the terrain layer among the standard 10 and 30 m derived images, but they are impressive when you find them. Based on the location of these patches of high-resolution terrain, and their appearance, it is pretty easy to deduce that Google is now incorporating bare earth LiDAR digital elevation models into the Google Maps terrain layer.
Thus far, I’ve noticed high-resolution data in downtown Portland, OR, the greater Los Angeles area, and Mount Saint Helens in Washington. There may be other examples of LiDAR-derived terrain in Google Maps since I haven’t searched very hard. If you are aware of other areas leave a comment.
Below are a few sites in Google Maps where you can clearly see the high-resolution data.
Downtown Portland, OR. Data are sourced from the Oregon LiDAR Consortium managed by the Oregon Department of Geology and Mineral Industries (DOGAMI). Note obvious building foundations, hillslope modifications, etc.:
Edge of LiDAR near Washington Park in Portland - bare earth LiDAR on the east side, 10 m (?) data on the west:
LiDAR bare earth data near Beverly Hills, CA. I’m not sure of the origin of these data - does anyone know if the original LiDAR point cloud and DEM data are publicly available?:
Obvious seam between LiDAR grids and lower resolution terrain data north of Yorba Linda, CA:
Finally, the very impressive Mount Saint Helens data. Presumably these are the data collected by NASA in partnership with USGS in 2003-2004 during a period of significant volcanic activity:
It is really nice to see these high-resolution terrain datasets making it into such a common and easily accessible platform like Google Maps. OpenTopography provides network-linked KMZ files to deliver LiDAR derived imagery data to Google Earth so that they are available to non-expert users, and direct incorporation of these data into the Google Maps terrain layer takes the accessibility of these data one step further. As the number of public domain LiDAR data collections increases, I’d expect that we’ll see more examples of LiDAR appearing in maps and online visualizations accessible to the general public.
An interesting, and logical follow on question to LiDAR in Google Maps, is when will Google will tackle the integration of high-resolution terrain data into the topographic mesh in Google Earth? For the Earth science community, 1 meter terrain data in Google earth would be revolutionary.
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We would like to call your attention to a topical session (oral) at the national GSA meeting in Denver in October:
T145. Virtual Tectonics
GSA Structural Geology and Tectonics Division; GSA Geoscience Education Division; GSA Geoinformatics Division; GSA Geology and Society Division; National Association of Geoscience Teachers
Declan G. De Paor, S.J Whitmeyer
Application of virtual reality to tectonics: virtual field trips, LiDAR, Gigapans, Google Earth, Second Life, virtual specimens, animations, simulations of tectonic and neotectonic processes, interactive maps, lunar and planetary VR, and the geology of exoplanets.
We encourage abstract submissions on topics that focus on using modern digital technology and/or cyber-based tools to address any variety of Earth or Planetary tectonics-related topics. In addition, we encourage abstracts that address education and/or research oriented themes.
Feel free to contact us if you have any questions, and remember that the deadline for abstract submissions is August 10. The link for abstract submissions is: http://gsa.confex.com/gsa/2010AM/top/papers/index.cgi?sessionid=25815
Steve Whitmeyer ()
Declan De Paor ()
Nancy Glenn from the Idaho State University Department of Geosciences Boise Center Aerospace Laboratory (BCAL) sent along a link to a collection of outreach videos they have been developing that provide 3D visualizations using LiDAR and other digital data. For example, the following video provides a narrated tour of the Snake River in eastern Idaho:
The BCAL videos page also features a 3D tour of the Borah Peak Earthquake rupture and an introduction to LiDAR technology. These resources, produced with National Science Foundation Idaho EPSCoR Program funding, are great resources for education and outreach.
Thanks to a close collaboration with OpenTopography colleague Alejandro Hinojosa at CICESE in Ensenada, Mexico, we have obtained 5 meter resolution LiDAR topography data for the epicentral region of the Sunday, April 4th 2010 magnitude 7.2 El Mayor - Cucapah earthquake in northern Baja, Mexico. These data, which cover an area of over 2,000 square kilometers southwest of Mexicali, were acquired in 2006 by the Instituto Nacional de Estadística y Geografía (INEGI), a Mexican government agency. We’ve been told that these data were collected from an elevation of 6000 m with GSD of 10 to 12 meters.
As I’ve done for the EarthScope LiDAR hosted by OpenTopography as well as the data collected following the January Haiti Earthquake, I’ve generated hillshade and slopeshde imagery from the DEM data and produced a network linked Google Earth KMZ file that can be used to access the imagery. Download the KMZ file using the button below and open in Google Earth to get started:
At the moment, we have not obtained permission from the INEGI to release the actual DEM data (and we do not have the point cloud data), but we hope that the derived imagery accessed via Google Earth will be helpful for researchers currently investigating ground rupture and other phenomena associated with last month’s earthquake. To assist groups working in the field who won’t have network access to connect to the imagery stored on OpenTopography servers, KMZs with the imagery stored locally can be downloaded below:
We anticipate that higher-resolution LiDAR topography will be collected along the ground rupture in the next few weeks. Clearly these pre-event data, although lower resolution than forthcoming data in the region, present an exciting opportunity for comparing pre- and post-event data to calculate near-field deformation along the rupture. We’re optimistic that we’ll be able to obtain permission to distribute both the DEM and point cloud INEGI data in the future so that they can be used for these types of analysis.
Dataset extent in Cyan. Mexicali in the upper right. US/MEX border in yellow:
Location of ground rupture across Highway 2, west of Mexicali:
Slopeshade image in region of greatest fault offset in the Sierra Cupapa range:
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As discussed in previous blog posts (here and here), LiDAR data have been collected over parts of Haiti following the January 12th earthquake. The data collected by the Center for Imaging Science at Rochester Institute of Technology (RIT), Kucera International, and ImageCat, Inc., has recently become available via an FTP site maintained by the USGS that is hosting geospatial data acquired in response to the Haiti earthquake. These data were collected during a campaign between January 21st and the 27th.
In order to make these data easier for all users to access, I downloaded and processed the filtered (bare earth) and unfiltered DEM data into hillshade images (315 degree illumination angle, 1 meter resolution) that can be viewed in Google Earth. The approach used was similar to what I’ve done for all of the EarthScope LiDAR imagery available via KML (more info is available in this AGU abstract). The result is roughly ~1.5 GB of hillshade imagery for Haiti hosted on OpenTopography servers that can be browsed seamlessly in Google Earth. Download the KML file using the button below and open in Google Earth to get started:
Port-au-Prince waterfront with slight transparency in the LiDAR to create a fusion with the very high-resolution base imagery in Google Earth:
Bedrock scarp(?) in linear fault valley southwest of Port-au-Prince:
A nice find by Ken Hudnut this afternoon using the KMZ file: Lateral spread / fissure features along the coast. Note how visible they are in the high-res Google Earth imagery, but when viewed in the bare earth the sharpness of the features has been removed by agressive vegetation classification. The features are prominent in the unfiltered grids however:
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Officially released earlier today, the Intermountain Seismic Belt (ISB) GeoEarthScope LiDAR dataset, covering parts of the Wasatch fault in Utah, and Yellowstone and Tetons National Parks in Wyoming, is quite spectacular. I’ve been browsing the data via the Google Earth KMZ hillshade file that I produced and thought I’d post some screen captures to encourage you to download the file and explore the data too. The DEM data that was used to generate these hillshades can be downloaded from the OpenTopography Standard DEM page. The full ISB point cloud will be available via OpenTopography soon.
The SRTM KML Project has released a very nice network-linked KML which displays shaded relief images derived from Shuttle Radar Topography Mission (SRTM) digital elevation models in Google Earth. Their website reports:
This version covers the entire SRTM dataset (80% of the land on the Earth). It is based on the SRTM V2 product. A new “fill” algorithm was developed at CCIC, which significantly improved the cartographic quality of the layer without compromising the accuracy.
The global SRTM shaded relief KML file can be downloaded from: http://srtmkml.googlepages.com/
A couple months ago I began a project to import all 50,000+ USGS Topographic Maps into Google Earth. This is a huge undertaking that will likely take me several more months to finish all 50 US States. These maps are intended to provide a free alternative to expensive commercial products that often cost $80 or more per state or charge monthly access fees. Plus you get the benefit of using the topo maps with Google Earth.
The Topo maps are saved as individual KMZ files which must be downloaded in their entirety before they will be visible in Google Earth. Most of the maps are less than 5 megabytes, but some are as large as 20 megabytes so the speed at which the maps load will depend greatly on the speed of your Internet connection.
Currently, topo quads are available for Arizona, Nevada, Colorado, and New Mexico.
Learn more and download the KML file at: http://www.gelib.com/usgs-topographic-maps.htm
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