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November 25, 2007 - Earth Now! tape delayed streaming low resolution Landsat imagery. November 25, 2007 - Perry Castaneda US Army Map Service Topos from the 1940s - but still useful and interesting. November 24, 2007 - See the ASTER GloVis download tutorial at: ASTER DEM GLOVIS Download Procedure. November 24, 2007 - Terrain overlay studies. See the work in progress article at: Custom Terrain Maps November 24, 2007 - CGIAR Consortium for Spatial Information archives a comprehensive global database of corrected SRTM data in GEOTIFF and ARC ASCII format. Notorious SRTM data voids are corrected using best available techniques, including contour line extension (see below). Data is available in large 5 degree tiles in either format. See the CGIAR SRTM download tutorial at: CGIAR SRTM Download Procedure. November 24, 2007 - The best source for corrected, void-filled SRTM data for the mountainous areas in Central Asia, China, Europe, Caucasus, Northern Andes and Southern Andes based on data from Jonathan de Ferranti’s Viewfinder Panoramas webpage. November 23, 2007 - Update of the ASTER DEM ordering procedure. See the revised article at: ASTER Download Tutorial November 19, 2007 - Free USGS topo maps for all USA in .pdf format at USGS Store. November 19, 2007 - New source of scanned Russian topo maps of Nepal and surrounding regions of central Asia at the Digital Topographic Map Library. November 5, 2007 - Great source of scanned Russian topo maps at Poeheli (thanks to Francios). November 4, 2007 - Drey article on the general technique for using ASTER data to generate DEMs. November 4, 2007 - Update: download sites for SRTM data GLCF or the NASA ftp site at NASA ftp site. October 25, 2007 - Tools for adding contour lines to Google maps images: Earthtools can be used by visiting the site, or add Elevation Contours by clicking the "Add Content" button and follow the instructions. October 8, 2007 - Excellent source for Russian military topo maps of the Ukraine. Hope you read Russian. Karta Ykpanhbi. October 8, 2007 - Source for excellent quality free USGS topographic maps at Libre Map Project. October 4, 2007 - Check out Flash Earth mashup of several online mapping web sites to produce global aerial images. April 16, 2006 - First HiRise Mars photos "The eight test images were taken several weeks after MRO successfully performed its Mars Orbital Insertion maneuver, which placed it in an elliptical orbit around Mars. Beginning in early April, MRO began dipping slightly into the atmosphere of Mars on each close pass by the planet to slow its velocity and eventually attain a circular polar orbit. Called aerobraking, it will take six months and 500 orbits to achieve the final science orbit." "During the aerobraking phase of MRO's journey, HiRISE and the other scientific instruments are turned off. During this time, scientists at the HiRISE Operations Center will be studying the following images and ensuring that HiRISE is ready for the 10,000 images it will obtain during the first three years at Mars." March 14, 2006 - See the new Google Earth article. March 13, 2006 - Mars maps at Google Mars site. March 3, 2006 - Helpful pointers to USA GIS data at the Stanford University Libraries and Academic Resources site. March 3, 2006 - A wealth of data (including ASTER L1A/L1B!) is available for free download at the UMIACS GLCF ftp site. August 28, 2005 - Download an Image Processing testbed program written as part of my recent course work at CCSU. April 12, 2005 - Alpine Mapping Guild/Martin Gamache Paper Martin Gamache has written an excellent survey document that discusses application of many of the common sources for free GIS data, including ASTER, SRTM, and Landsat. This paper will answer many of your questions regarding these datasets.
March 20, 2005 - February 13, 2005 - ESA Mars Express Imagery See the new article describing the stunning ESA Mars Express imagery. February 9, 2005 - BLACKART 3D Module Tutorial See the new article describing the BLACKART 3D module and stereo pair tutorial. January 27, 2005 - Download BLACKART version: v4.02 with 3D Rendering Capability. 1) The latest BLACKART 4.02 upgrade includes the ability to create stereo pair images. January 9, 2005 - Download BLACKART version: v4.01 with 3D Rendering Capability. 1) The latest BLACKART 4.01 upgrade includes the ability to save your 3D image in .jpg format. 2) Examine a BLACKART version v4.01 desktop screenshot. January 3, 2005 - Download BLACKART version: v4.00 with 3D Rendering Capability. 1) The latest BLACKART 4.00 upgrade includes 3D rendering capability. You are now able to render your interpolated image in 3D. 2) I am not an OpenGL programming expert and BLACKART is not 3DEM. However, I expect to improve the module considerably in the future. 3) Thanks to Dr. Bradley Kjell of CCSU for the opportunity to study graphics programming in his wonderful course this past semester.
January, 2 2005 - Email Notice. June 20, 2004 - Download BLACKART version: v3.99 . 1) I corrected an error in the program that caused the edge node known values to float during Laplacian interpolation instead of staying locked 2) BLACKART can now save DTED1 files. 3) Latitude and longitude are now reported for DTED1 files. 4) SRTM-3 patching using DTED1 data is now available. (Note: corner coordinates of tiles must match exactly for this feature to work properly.) 5) SRTM-1 patching with expanded DTED1 data is now available. The SW corners of the tiles must match for this feature to work. (All of the DTED1 interpolation features are beta at this point. I am posting them as I write them, but before all the features, GUI error trapping, etc. are in place.)
May 24, 2004 - NGA Raster Roam. The NIMA Geospatial Engine has apparently been replaced by the new NGA Raster Roam site. I am in the process of updating all of the links on this site. May 23, 2004 - Geoscience Australia!. This significant data sighting was reported by Mitchell Herbertson this weekend. The site contains topographical, DEM and vector GIS data for all of Australia. The 9 arc-second (~250m) DEM data is especially important for a couple of reasons. Firstly, Australian SRTM data will not be available until later in the year. When it does become available, this set will provide excellent patching material because it is of higher resolution than DTED0 or SRTM30 and it is derived from a completely different source, so any errors are unlikely to be coincidental with the SRTM-3 data. The data is in an ER-Mapper format that is not documented on the website. I modified BLACKART v3.92 so that it will read the files. I will be completing the patch utility so that it is available when the SRTM data is released. In the meantime, this data provides a useful source for medium-resolution DEM data for Australia. May 3, 2004 - Download BLACKART Help File. BLACKART help file in PDF format. In a font size that you can actually read. May 11, 2004 - International Topo Maps. What do you do when the topographic map for your non-USA location of interest is not avaialable? Make your own using low-cost or free tools. Look for the upcoming article appearing in June. (Thanks to Cristian and Vasile for setting me straight on the map title.) May 2, 2004 - New BLACKART Tutorial.. View the new article on using DTED0 and SRTM30 Digital Elevation Model data to patch SRTM-3 files using the latest utilities and techniques. April 11, 2004 - S-DES v1.02 (Simplified) Data Encryption Standard. Another unrelated application: the "companion" to my earlier S-RSA public key encryption application: S-DES symmetric key encryption application. This is the classic "toy" Schaefer S-DES algorithm with 10 bit key strength and 8-bit block size. However, it is enhanced with Cipher Block Chaining mode and triple S-DES/CBC mode for up to 28 bits of key strength and resistance to cryptanalysis, at least by students and amateurs. April 7, 2004 - GEOTIFF4 UpgradesI fixed a problem that caused a memory deallocation error that occurred when writing a USGS ASCII DEM file. April 1, 2004 - SRTM Africa Data is now available from the NASA SRTM ftp site. March 27, 2004 - S-RSA v1.03 (Simplified) Public Key Cryptography. OK, so its not cartography and its not PGP, but it is my latest creation, a 32-bit keyspace, 24-bit block simplified RSA public key file encryption application. Its purpose is educational, and does not represent a practical encryption scheme. However, it is a little easier to see how the RSA protocol works using this application than PGP, which streamlines the process at the expense of showing what is going on under the hood. How would you break this code? Although fairly secure from cryptanalysis, a crack can be computed in less than 1000ms on your computer. March 5, 2004 - NIMA Tactical Pilotage Charts Article. Brief article on NIMA Tactical Pilotage Charts. February 29, 2004 - GEOTIFF4
Upgrades . I have fixed several GEOTIFF4 bugs
reported by users over the past several weeks, including switched row and
column label fields and lack of memory deallocation. The latest version is
1.52. February 11, 2004 - NASA Gateway to Astronaut Photography of Earth Article . First new data sightning of the year. Explore this interesting source of free satellite imagery. The NASA Gateway to Astronaut Photography of Earth contains 546,548 images taken from the International Space Station, Space Shuttle, and other manned platforms. January 16, 2004 - BLACKART SRTM Digital Elevation Model File Repair Tutorial. Learn how to use BLACKART to read and repair SRTM and ASTER Digital Elevation Model files in the new tutorial. This tutorial includes instructions on the new DTED0 DEM merge module. (I recently added a paragraph outlining the exact menu selections for the DTED0 merge operation, which I had accidently left out of the article previously.) December 28, 2003 - SDTS2TER and MDEM2TER Recompilations. I recompiled the old console application converters SDTS2TER and MDEM2TER using Microsoft VC++ as a result of a couple of user inquiries. These versions may be useful for anyone having difficulties running the original Borland Turbo C++ versions. December 14, 2003 - ADTI SDTS DEM Data Source. Many of the patrons of this site may know that valuable USGS SDTS DEM data is available for free download from gisdatadepot.com. Fewer may know of a second source for this data at adti-us.com. December 13, 2003 - BLACKART Difficult Contour Map Tutorial. This is the follow-up article to the BLACKART preprocessor tutorial. This article explains how to use BLACKART to extract a digital elevation model for a real-world topographic map, cluttered with lots of text, roads, watercourses, background colors, etc. December 13, 2003 - BLACKART Crowded Contour Line Tutorial. Find out how to handle crowded contour lines using BLACKART in this new tutorial inspired by a user enquiry. November 23, 2003 - "Long Awaited" BLACKART Graphics Preprocessor Tutorial. See the new how-to article that introduces the BLACKART graphics preprocessor module. November 20, 2003 - Canadian CDED DEM Data. A new free source of Canadian CDED DEM data has recently become available at the GeoBase website. Data is available in resolutions of 1:50,000 and 1:250,000. Data format is Canadian Digital Elevation Data (CDED) format, which is very close to USGS ASCII DEM format. MicroDem, 3DEM and Global Mapper were all able to handle the two test files that I down loaded without problems, although MicroDem misread the header file slightly. The site is a little cumbersome to navigate. Look for the minuscule "data" link at the top of the page to get started. (I couldn't help feeling that they don't really want you to find it.) You will have to negotiate a couple of unnecessary screens, agree to the license agreement (twice), and give them your email address before the URL is sent out after a short delay. The release of this free Canadian DEM data is a very welcome step in the right direction regarding government policy toward the national DEM data set. Let's hope that the trend to increase public access to important geographical data continues. November 4, 2003 Eurasia SRTM Data Set On Line . SRTM data for Europe and Asia is now available at the SRTM Eurasia FTP Site. With all of North and South America available (see earlier news item) DEM data for much of the world is available at 90m resolution. Thanks to Eric from Berlin for the timely information. Note: I have had many comments regarding the unprocessed quality of much of this dataset, i.e. lots of missing data and bad data regions. September 21, 2003 - UC Berkeley Map Library. I recently discovered an interesting source of international topos, including hundreds of Russian and AMS maps. The source is the UC Berkeley Map Library. First the good news: the collection as impressive, with a sizeable quantity of maps including hard-to-find Russian topos of many areas of the world where free coverage was previously unavailable. Now the bad news: the maps are apparently not scanned in at high enough resolution to allow easy separation of the contour lines to create DEMs using BLACKART. However, the topos are still useful for many purposes. See the new Berkeley Map Library article. July 22, 2003 - 90m South American SRTM DEM Data 90m resolution SRTM DEM data is now available for South America. The data is available from two locations: by ftp at the South America USGS FTP site and by seamless data distribution at USGS Seamless Data Distribution (select the "View and Order Data Sets, International Viewer). This data, despite its relatively low resolution, should provide a welcome alternative to DTED0 which was the only (non-ASTER) alternative in the past. Thanks to Mohamad and Robert for the information. June 23, 2003 - BLACKART Franklin Approximation Conjugate Gradient Iterative Contour Line Interpolator Those of you who have been breathlessly following my Master's Degree project at RPI Hartford have probably been wondering when I would convert all the developmental and research code into a useful application. Well, here it is, another piece of research-grade code written in C++, currently featuring a sub-optimal implementation of the Saunders-Paige conjugate gradient iterative least squares solver. (To be more precise, solving large input files (greater than around 160,000 nodes) at present is slow because of the representation of the sparse matrix as a simple index file. A more efficient representation would allow faster computations for large data sets by reducing excessive memory paging. I should have an improved version soon.) BLACKART in its present state takes a space-separated ASCII elevation contour file as input and outputs either a USGS ASCII DEM or ASCII xyz interpolated surface file. The program combines the sparse matrix index file module, fast Laplacian central difference solver, Saunders-Paige CG solver and USGS ASCII DEM writer into a single console application. So what is the point? BLACKART represents the second (and arguably more difficult) half of a general purpose application to extract high quality DEMs from topographic maps. The first half contains the raster-to-vector and image processing algorithms necessary to prepare the contour elevation grid file for input to BLACKART. Once I have the second half fully developed, I plan to start working on the first half and eventually put together a useful application for extracting DEMs from topos. In the mean time you can download the prototype code and experiment with generating DEMs from the sample contour files included or ones that you prepare yourself. See the complete Blackart Interpolation article for details. April 2003 - War Images of Baghdad Examine high resolution satellite images of Baghdad at the Digital Globe website. The site offers a couple of full-resolution 0.9m and 0.6m images of the city including a color composite image taken in September, 2002 and a grayscale taken March 27, 2003 along with several subset images showing recent bomb damage. Additional photos can be seen at the War Images of Baghdad article. For the most comprehensive source of military information on the internet, including maps, satellite images, order of battle, and a great deal of additional political, geographical and social information about Iraq, visit the invaluable Global Security site. March, 2003 USGS ASCII DEM File Specification Periodically, people ask me for a link to the USGS ASCII DEM File Specification. The last time I tried I could not find one, so here is a copy in case anyone needs it. GEOTIFF4 Correction: I corrected a serious problem with GEOTIFF4 that was reported by a user. When saving a subset image, the program appended a newer version of an output USGS ASCII file to an older version if the file already existed instead of overwriting the existing file as it should have. I corrected the error and reposted the program. I have no idea why I set the append flag when opening the output stream in the first place and why I did not catch this embarrassing problem during development. It's probably a result of losing my mind many years ago. I am very sorry for the confusion this must have caused users of the program. February 12, 2003 - SRTM Rocket February marked the
three year anniversary of STS-99, the shuttle mission that mapped 80% of
the earth's surface using an interferometric radar instrument. After three
years of foot-dragging and unkept promises, NIMA (NASA's "partner") has
yet to authorize release of non-US SRTM DEM datasets. In case you have not
been following this sad story, the plan is to degrade non-US data from a
marginally adequate 30m (instrument resolution) to a less useful 90m
resolution prior to release to the public in 2004 (we are now told ). All
that our multi-billion dollar SRTM investment has returned so far, three
years post-launch, is an inferior duplication of the USGS NAD and a flashy
SRTM website. The "showcase" images offered by NASA are more insulting
than enlightening. Earth to NASA: just give us the data!
MDEM2BSQ Update At the request of a user I recompiled MDEM2BSQ using VC++ in order to allow larger input files to be processed. The new program is called BIGBSQ and it should process input files of "unlimited" (>65MB) size. EarthSat Link Update Thanks to Albert Groebli for sending in a dead link alert for the NASA ESAD MrSid site. The link to this great site is now corrected. (Note: some firewalls will not like this link.) RPI Master's Project It has been my good fortune to be able to work with Dr. William Randolph Franklin at RPI Troy in Troy, NY USA on an interesting problem in computational cartography. I am doing this work as partial fulfillment for the requirements of my MSCS degree at RPI Hartford. My project is entitled: "A Better Interpolation of Large Contour Line Data Sets using an Over Determined Laplacian PDE". This project is related to the more general problem of producing DEMs from contour line data. Dr. Franklin is a well-known applied mathematician with expertise in computational cartography. Anyone interested in following my progress can take a look at my school web page at RPI Hartford 359 unread Mail messages in your Inbox...
As those of you who have attempted to contact me by email
over the last few months have discovered, I am falling way behind in
answering my mail,due to my school and work schedule. I hope to resume
correspondence again at the end of this semester, which should be my last
for now. In the meantime as I am merely scanning my email, the following
would help: University of Maryland GLCF! The University of Maryland's Global Land Cover Facility represents the finest source of free Landsat TM, ETM and MSS imagery on the planet and is one of the most important sites on the internet. Read about this exciting data source and their recently upgraded search engine and GIS database in the new article entitled University of Maryland GLCF. Free Aster L1B! LP-DAAC has recently opened its promised ASTER L1B Data Pool ftp free download site for ASTER and MODIS data. Although coverage is limited to the United States (and not even the entire United States) this is a welcome gesture by LP-DAAC, the USGS and NASA. Let's hope they find a way to expand this offering. High Resolution Image from Landsat 15m Band! Learn how to combine low resolution Landsat color bands with the high resolution panchromatic band to make a high resolution HSL true color composite. See the article entitled Landsat HSL Composite from Panchromatic Band. Free 3DEM Everyone's favorite GIS application is now freeware! This excellent program, featured in several articles on this page is available for free download at Simtel.net. Free NASA Imagery Exchange Data! Learn where to get free NASA Imagery Exchange Data in the new article only at terrainmap.com. Free EarthKam Data! Learn where to get free EarthKam Space Station Imagery in the new article only at terrainmap.com. Free EarthSat Data! Learn where to get free EarthSat imagery in the new article Free EarthSat Satellite Imagery. Note: I am in the process of updating all the articles on this page to redirect referenced links toward the appropriate free data sources wherever possible. Most of this work is complete. Refer to the News section of this page for the latest information. Free Landsat 7 Data! Learn where to get free Landsat 7 imagery and how to process it in the new article Free Landsat 7 Satellite Imagery. Regrettable Trend: Sadly, effective August 12, 2002 LP-DAAC has started charging USD $60 for each formerly free ASTER L1A/L1B granule. (Thankfully ASTER DEMs are still free.) ASTER imagery was formerly the highest quality free satellite data available anywhere. United States citizens who feel as I do that after paying with our tax dollars for the satellite, launching the satellite, maintaining the groundstation, processing the data and administering the database where the data is archived that perhaps we already own the data may wish to contact LP-DAAC at mailto:edc@eos.nasa.gov%20<mailto:edc@eos.nasa.gov> to express this opinion. Maybe the costs associated with making the data available do justify the price, but as is usual from our government agencies no explanation was considered necessary. My Apologies: for all the unanswered emails that I have accumulated this summer. I am in the final year of a demanding MSCS program at RPI Hartford and have been overwhelmed by the demands of school and my job. I formerly spent at least an hour a day answering emails. Eventually I needed that time to devote to studies and as a result I have a considerable backlog. I plan to improve my FAQ page to try to answer more questions using that forum. I apologize again but it is important to me to finish my degree work so that I can devote more time to writing better GIS applications. GEOTIFF4 Version 1.49!: GEOTIFF4 can now read ASTER DEM I16 and FP32 HDF format as well as ASTER geotiff format. The program has graphics capability, subsetting, the ability to drop row and column markers, adjust elevations and more. The program outputs DEM files in USGS ASCII, flat binary, and terragen format. Download it for free only at terrainmap.com! < >ASTER Relative DEM Vertical Errors: I have received several emails recently reporting apparent vertical errors in ASTER relative DEM data as compared to known standards. Read more on this including information from EOS-EDC in the FAQ ASTER section. ArcView Upgrades I received a couple of emails recently indicating that the output from my USGS ASCII writer cannot be read by ArcView and ArcInfo software. I determined that the strict specification requires that the ASCII file be divided into 1024 byte blocks delimited by 0x0d0a. I rewrote the writers for SDTS2DEM, MDEM2DEM and GEOTIFF4 to incorporate this requirement. This did some good because GlobalMapper could not read the output in the past and now it can. I am hoping that ArcView can also read the output, and am in the process of finding someone with ArcView to test them for me. I am posting these versions as betas for now. Those having trouble with the outputs can get at the files by clicking GEOTIFF4, MDEM2DEM5 and SDTSDEM7. Upgrade: Resequenced the creation and destruction of internal data structures within MDEM2BSQ so that memory usage is decreased by 33%. This should allow larger files to be processed. Bug Fix: Modified MDEM2DEM so that it handles 10m SDTS source DEMs correctly. Bug Fix: I was notified by a user that BANDPASS crashes when fed a very large >50mB input .tif file due to a page fault error. This is important because some DOQs needing redeye correction can be more than 100MB in size. The problem was in the Borland compiler that I normally use. I recompiled the program using Microsoft Visual C++, and this has apparently fixed the problem. I will post it as a separate program until I do more testing, at which time it will probably replace BANDPASS. I call the new program BIGBANDPASS. Anyone using BANDPASS for very large files should use the new program instead. Bug Fix Added a line of code to BANDPASS to keep it from crashing horribly if an illegal file is input. Sorry. Bug Fix Corrected SDTSDEM2 so that it reports the UTM zone and the four corner coordinates to the console correctly. Converter: Convert MicroDEM DEM files to .BSQ flat binary format. This format can be used in the creation of MicroSoft Flight Simulator terrains from USGS DEM data. The new program is called MDEM2BSQ. FS terrain users: let me know if you find bugs or have suggestions. (Note: I had my doubts about the rotation of the output file but I am told that the way it is presented is correct.) Converter SDTSTER4 converts 10m and 30m 7.5' SDTS DEM files to Terragen .ter format. This program can convert 10m BFP(32)(decimal meter) format as well as BI(16) just like SDTSDEM2 below. This program supercedes SDTSTER3 Converter: SDTSDEM2 converts 10m and 30m 7.5' SDTS DEM files to USGS native DEM format for input to legacy applications unable to read the modified SDTS profiles such as 3DEM70 . This program can convert 10m BFP(32)(decimal meter) format as well as BI(16). It can handle both new and old SDTS formats. This utility has been tested successfully against Microdem, DEMWorks, 3DEM, 3DEM70, and DEM2TGA6. This utility is the testbed for an upgraded SDTS reader that I will incorporate into all the SDTS utilities on this page. I will leave SDTS2DEM up for a while in case there are bugs in SDTSDEM2 that I do not know about. Eventually, SDTS2DEM will be superceded by SDTSDEM2. Thanks to George C. Miller of the USGS for supplying information that made the upgrade possible. Revised Converters: DEM2TGA7 and DEM2POV2. can now handle CDED data format. I discovered a bug in the DEM reader parts of these programs recently while working with Canadian CDED data files. The file reader was not handling certain horizontal and vertical datum values properly causing the program to hang. I fixed this problem and now DEM2TGA7 and DEM2POV2. can now read CDED as well as USGS native DEM successfully. My apologies to anyone having trouble with these converters for this reason. Converter: MDEM2TER converts from MicroDem native DEM format to Terragen .ter format. With this utility, Terragen can now ingest any DEM format that MicroDem can, and that's a lot. It is now possible to use the powerful file merge capabilities of MicroDem and then input the merged files to Terragen for rendering. See the tutorial below. Converter: MDEM2DEM (Revision 1) converts MicroDem DEM format to USGS native DEM format. This allows programs that read only USGS DEMs to take advantage of MicroDem utilities. For example, you can import two 7.5' SDTS files into MicroDem, merge them, then save the merged image as a MicroDem DEM. Run MDEM2DEM< color=#000000> on the MicroDem output file and create a USGS DEM file suitable for input to another application that reads only USGS DEMs. Converter: For those of you
who need to convert from SDTS to 24-bit TGA format there is now SDTS2TV. It
converts 30m 7.5' SDTS DEM files to 24-bit TGA format such that the
elevation values range from zero to 16,000,000. Data is written to three
bytes in the order: lowbyte, midbyte, highbyte. |
March 1, 2008 - SRTM accuracy report and related data is available 