Posts Tagged ‘30m’

The Accuracy and Precision Revolution: What’s ahead for GIS? (Nighbert via ArcUser)

Wednesday, April 7th, 2010

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[Editor’s note: “As we try to integrate highly resolved data into existing GIS, the errors in legacy data will become more apparent.” Jeff outlines the problem through his experience at the BLM in Oregon. Jeff is also responsible for early “bump mapping” of digital terrain models (DEMs).]

Republished from the ESRI ArcUser Winter 2010.
By Jeffery S. Nighbert, U.S. Bureau of Land Management

The ability to obtain precise information is nothing new. With great patience and skill, mapmakers and land surveyors have long been able to create information with an impressive level of accuracy. However, today the ability to determine and view locations with submeter accuracy is now in the hands of millions of people. Commonly available high-resolution digital terrain and aerial imagery, coupled with GPS-enabled handheld devices, powerful computers, and Web technology, is changing the quality, utility, and expectations of GIS to serve society on a grand scale. This accuracy and precision revolution has raised the bar for GIS quite high. This pervasive capability will be the driver for the next iteration of GIS and the professionals who operate them.

When I say there is a “revolution” going on in GIS, I am referring to the change in the fundamental accuracy and precision kernel of commonly used geographic data brought about by new technologies previously mentioned. For many ArcGIS users, this kernel used to be about 10 meters or 40 feet at a scale of 1:24,000. With today’s technologies (and those in the future), GIS will be using data with 1-meter and submeter accuracy and precision. There are probably GIS departments—in a large city or metro area—where this standard is already in place. However, this level of detail is far from the case in natural resource management agencies such as Bureau of Land Management (BLM) or the United States Forest Service. But as lidar, GPS, and high-resolution imagery begin to proliferate standard sources for “ground” locations, GIS professionals will begin to feel the consequences in three areas: data quality, analytic methods, and hardware and software.

Continue reading at ArcUser . . .

Updating Natural Earth Populated Places (Kelso)

Tuesday, January 12th, 2010

Dick Furno and I have been busy revising and expanding the populated places included with Natural Earth, released in December. We’re adding around 1,000 places to get to ~7,300 total towns and settlements around the world. We include more admin-1 capitals and make a first stab at linking to GeoNames via their unique IDs. Dick has gone over the towns and created a new 30m scale rank that helps cut the 20m clutter in half. We hope to have the update pushed out by the end of January.

Here’s a preview: Click images to see larger version

Added locations
(red = added general place, black = added admin-1 place at less than 10m scale rank, grey = existing places)

added_place_or_admin_1_capital

Scale rank changed
(red = change, grey = no change to existing or added at less than 10m scale rank)

scale_ranks

Changed the name, location, feature class, population, or other property
(blue = changes to existing features, grey = existing or added)

names_location_featureclass_population

Places with GeoName ID linkages
(green = with ID, grey = lacks ID for mostly small population settlements)

geonames_id

New Global 30m DEM Topographic Data via ASTER (NASA)

Tuesday, June 30th, 2009

pia12090-browse

[Editor’s note: NASA and Japan’s Ministry of Economy, Trade and industry (METI) released new 30 meter resolution Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Global Digital Elevation Model (GDEM) to the worldwide June 29, 2009. The new dataset covers the high latitudes with increased precision over SRTM, although the cloud cover problems that plauge ASTER can prove problematic. The servers were being hit heavy on Monday and data download is convoluted. The preview of the data uses a curious data exploration color ramp with inverted shading. Thanks Tom and Laris!]

Republished from NASA.

PASADENA, Calif. – NASA and Japan released a new digital topographic map of Earth Monday that covers more of our planet than ever before. The map was produced with detailed measurements from NASA’s Terra spacecraft.

The new global digital elevation model of Earth was created from nearly 1.3 million individual stereo-pair images collected by the Japanese Advanced Spaceborne Thermal Emission and Reflection Radiometer, or Aster, instrument aboard Terra. NASA and Japan’s Ministry of Economy, Trade and Industry, known as METI, developed the data set. It is available online to users everywhere at no cost.

“This is the most complete, consistent global digital elevation data yet made available to the world,” said Woody Turner, Aster program scientist at NASA Headquarters in Washington. “This unique global set of data will serve users and researchers from a wide array of disciplines that need elevation and terrain information.”

According to Mike Abrams, Aster science team leader at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., the new topographic information will be of value throughout the Earth sciences and has many practical applications. “Aster’s accurate topographic data will be used for engineering, energy exploration, conserving natural resources, environmental management, public works design, firefighting, recreation, geology and city planning, to name just a few areas,” Abrams said.

Previously, the most complete topographic set of data publicly available was from NASA’s Shuttle Radar Topography Mission. That mission mapped 80 percent of Earth’s landmass, between 60 degrees north latitude and 57 degrees south. The new Aster data expand coverage to 99 percent, from 83 degrees north latitude and 83 degrees south. Each elevation measurement point in the new data is 30 meters (98 feet) apart.

“The Aster data fill in many of the voids in the shuttle mission’s data, such as in very steep terrains and in some deserts,” said Michael Kobrick, Shuttle Radar Topography Mission project scientist at JPL. “NASA is working to combine the Aster data with that of the Shuttle Radar Topography Mission and other sources to produce an even better global topographic map.”

NASA and METI are jointly contributing the Aster topographic data to the Group on Earth Observations, an international partnership headquartered at the World Meteorological Organization in Geneva, Switzerland, for use in its Global Earth Observation System of Systems. This “system of systems” is a collaborative, international effort to share and integrate Earth observation data from many different instruments and systems to help monitor and forecast global environmental changes.

NASA, METI and the U.S. Geological Survey validated the data, with support from the U.S. National Geospatial-Intelligence Agency and other collaborators. The data will be distributed by NASA’s Land Processes Distributed Active Archive Center at the U.S. Geological Survey’s Earth Resources Observation and Science Data Center in Sioux Falls, S.D., and by METI’s Earth Remote Sensing Data Analysis Center in Tokyo.

Aster is one of five Earth-observing instruments launched on Terra in December 1999. Aster acquires images from the visible to the thermal infrared wavelength region, with spatial resolutions ranging from about 15 to 90 meters (50 to 300 feet). A joint science team from the U.S. and Japan validates and calibrates the instrument and data products. The U.S. science team is located at JPL.

For visualizations of the new Aster topographic data, visit: http://www.nasa.gov/topics/earth/features/20090629.html .

Data users can download the Aster global digital elevation model at: https://wist.echo.nasa.gov/~wist/api/imswelcome and http://www.gdem.aster.ersdac.or.jp .

For more information about NASA and agency programs, visit: http://www.nasa.gov .

JPL is managed for NASA by the California Institute of Technology in Pasadena.