<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">See the following announcement. NASA (USA) will release high resolution DEM's of the globe, produced from the Terra ASTER satellite, at no charge. You can check out the web announcement at <<a href="https://lpdaac.usgs.gov/lpdaac/about/news_archive/monday_june_22_20092">https://lpdaac.usgs.gov/lpdaac/about/news_archive/monday_june_22_20092</a>>. As a Terra ASTER user, I've been using the DEM's for several years and found them to be a very good high-resolution (30x30m) topography source. <div><br></div><div>Michael</div><div><br></div><div>================== announcement ====================<br><div><br></div><div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">ASTER Global DEM </div><p style="margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Times New Roman; min-height: 15.0px"> <br class="webkit-block-placeholder"></p><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">Following review of the validation results, METI and NASA have decided to jointly release the </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">ASTER GDEM on <b>June 29, 2009</b>. Previously, METI and NASA announced their intent to </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">contribute the ASTER GDEM to the Global Earth Observation System of Systems (GEOSS). </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">Upon release, the ASTER GDEM will be available at no charge to users worldwide via </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">electronic download from ERSDAC and from NASA’s Land Processes Distributed Active </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">Archive Center (LP DAAC) by visiting http://www.gdem.aster.ersdac.or.jp/ </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">and https://wist.echo.nasa.gov/~wist/api/imswelcome/, respectively. </div><p style="margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Times New Roman; min-height: 15.0px"> <br class="webkit-block-placeholder"></p><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">The ASTER instrument was built by METI and launched onboard NASA’s Terra spacecraft in </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">December 1999. The ASTER instrument uses the nadir-viewing and the backward-viewing </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">telescopes; together they enable along-track stereoscopic capability to generate stereo data with </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">a base-to-height ratio of 0.6. The spatial resolution is 15 m in the horizontal plane. One nadir-<span style="font: 12.0px Helvetica"> </span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">looking ASTER VNIR scene consists of 4,100 samples by 4,200 lines, corresponding to about </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">60 km-by-60 km ground area. </div><p style="margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Times New Roman; min-height: 15.0px"> <br class="webkit-block-placeholder"></p><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">The methodology used to produce the ASTER GDEM involved automated processing of the </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">entire 1.5-million-scene ASTER archive, including stereo-correlation to produce 1,264,118 </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">individual scene-based ASTER DEMs, cloud masking to remove cloudy pixels, stacking all </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">cloud-screened DEMs, removing residual bad values and outliers, averaging selected data to </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">create final pixel values, and then correcting residual anomalies before partitioning the data into </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">1<span style="font: 12.0px Helvetica">°</span>-by-1<span style="font: 12.0px Helvetica">°</span> tiles. It took approximately one year to complete production of the beta version of the </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">ASTER GDEM using a fully automated approach. </div><p style="margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Times New Roman; min-height: 15.0px"> <br class="webkit-block-placeholder"></p><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">The ASTER GDEM covers land surfaces between 83<span style="font: 12.0px Helvetica">°</span>N and 83<span style="font: 12.0px Helvetica">°</span>S and is composed of 22,600 </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">1<span style="font: 12.0px Helvetica">°</span>-by-1<span style="font: 12.0px Helvetica">°</span> tiles. Tiles that contain at least 0.01% land area are included. The ASTER GDEM is </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">in GeoTIFF with geographic lat/long coordinates and a 1 arc-second (30 m) grid of elevation </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">postings. GDEM is referenced to the WGS84/EGM96 geoid. Pre-production estimated </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">accuracies for this global product were 20 meters at 95% confidence for vertical data and 30 </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">meters at 95 % confidence for horizontal data. Initial validation studies concluded that the </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">ASTER GDEM generally meets the pre-production accuracy predictions, but results do vary </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">and include areas where GDEM accuracy does not meet<b> </b>the<b> </b>pre-production estimates<b>. </b></div><p style="margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Times New Roman; min-height: 15.0px"> <br class="webkit-block-placeholder"></p><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">Land surface topography is one of the most fundamental geophysical measurements of the </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">Earth, and it is a dominant controlling factor in virtually all physical processes that occur on the </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">land surface. Land surface topography also significantly controls processes within the </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">overlying atmosphere and reflects the processes within the underlying lithosphere. </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">Consequently, topographic information<b> </b>is<b> </b>important across the full spectrum of earth sciences, </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">and the availability of an up-to-date, high resolution (1-arc-sec or less) global DEM remains a </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">priority of earth scientists for a long time. The ASTER GDEM is expected to meet the </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">requirements of many users for global topographic information. </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; ">=============================================================</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal 'Times New Roman'; "><br></div><div apple-content-edited="true"> <div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><div><div>____________________</div><div>C. Michael Barton, Professor of Anthropology</div><div>Director of Graduate Studies, School of Human Evolution & Social Change</div><div>Director, Center for Social Dynamics & Complexity</div><div>Arizona State University</div><div><br></div><div>Phone: 480-965-6262</div><div>Fax: 480-965-7671</div><div>www: <www.public.asu.edu/~cmbarton></div><br></div></div><br></div><br class="Apple-interchange-newline"> </div><br></div></div></body></html>