DEM2TOPO

DEM2TOPO

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About

DEM2TOPO is a program to generate vector contour levels from freely available digital elevation model (DEM) data. These contour vectors are ideally suited for upload to portable GPS units where commercial topographic maps are unavailable or inadequate. With a few simple steps and the appropriate software, topo maps can be uploaded to Garmin GPS units that support mapping (see the Using DEM2TOPO section, below). The program is designed for Canadian DEM files , but those for other countries using the ASCII version of the USGS DTED file format should work. GeoTIFF files are also supported, but currently only those written by 3DEM have been tested. The Canadian Digital Elevation Data (CDED) consists of an ordered array of ground elevations at regularly spaced intervals. These CDED are based on National Topographic Data Base (NTDB) digital files at the scale of 1:50,000 and 1:250,000, according to the National Topographic System (NTS). This data set is no longer maintained, but still available for download at geogratis.gc.ca. The file format specification is available here and at the GeoGratis site. DEM2TOPO is written in IDL, which is a high level interpreted language for scientific data analysis. Since it is an interpreted language, you must register, download and install the freely available IDL Virtual Machine to run the program, in the same way that the JAVA virtual machine is required for using JAVA code. IDL is platform-independant, and DEM2TOPO should work on Windows, Linux and Mac machines. You must download the full IDL installation in order to use the virtual machine. Alternatively, you can download this file which runs on Windows only and includes the virtual machine: Download the prebuilt RT version. If you already have the RT or VM version installed, you only need to download the zip file at the top and overwrite the dem2topo.sav file in your existing directory. Click here for a sample polish format file (482 KB) created by DEM2TOPO, covering a local river valley. The contour spacings are 10, 50, and 100m. Simplification Factor is 1. Using DEM2TOPO License agreement The program is beerware. Can't send me a beer? Feel free to make a donation instead.. A handful of people have generously donated a few beers- you know who you are. Thanks. I think I've recouped about an afternoon's worth of effort so far..

Known Issues

• The map area may not be perfectly square when printing.
• GeoTIFF files that do not contain datum or projection tags are assumed to be WGS84 and Lat/Lon.
• USGS DTED format files written by 3DEM will not work since 3DEM does not write the Lat/Lon coordinate of the map in the file header. GeoTIFF files written by 3DEM will work.
• DEM data sets with missing values will result in a stack of contour levels around the missing areas
• USGS DTED or SRTM format files that do not have 1201x1201 elements, will not work. Convert to GeoTIFF first for these files.
• When running on Windows, DEM2TOPO will only be able to use ~1.2 GB of RAM, even if there is more physical memory in the system. For very large maps, DEM2TOPO may run out of memory, in which case the only solution is to use smaller maps or larger intervals.

Common Blunders

• You don't need to process maps one at a time. If you have multiple DEM files to process with the same contour settings, just select them all in the 'Select DEM file(s)' dialog.
• If you get lines around the edges of your maps, deselect the 'Close Outer Contours' checkbox.
• If you can't load a DEM file or get error messages, create a GeoTIFF of your model using an application like 3DEM first.

Download

Note: deleting the 'dem2topo.var' file from the DEM2TOPO directory before running will cause DEM2TOPO to generate a new configuration file with default settings. If the 'dem2topo.var' file or the 'dem2topo.tbl' files aren't found in the working directory, DEM2TOPO will prompt the user for the location. When downloading a new version, you may have to delete your old 'dem2topo.var' file.

3.2

(Mar 17, 2011)

• Minor rebuild. Compatible with IDL 8.0.

3.1

(Sept 26, 2008)

• Fixed bug in ESRI and DXF output where units were not scaled properly.

3.0

(Aug 12, 2008)

• Fixed bug reading GeoTIFF files from http://srtm.csi.cgiar.org that don't contain proper tags.
• Minor display improvements.

2.9

(May 22, 2007)

• Added more meaningful error message for GeoTIFF files that don't contain proper coordinate tags.

2.8

(Mar 7, 2007)

• Printing fixed. Now properly prints vector plots with bitmap background to postscript printers.

2.7

(Oct 26, 2006)

• Minor reduction in memory usage when the plot is disabled.

2.6

(Sep 30, 2006)

• Fixed a bug where the program would crash if an imported levels file did not contain values for all 3 contour groups.

2.5

(Aug 25, 2006)

• Minor bug fixes.

2.4

(Jul 18, 2006)

• The CDED data format seems to have changed slightly. Fixed a bug when parsing the horizontal datum in the new files available at the GeoBase site.

2.3

(May 6, 2006)

• Fixed a bug in the interval input fields.
• Fixed a bug in where contours were clipped above 10000 feet or meters.

2.2

(Apr 24, 2006)

• Added a feature to optionally create closed polygons for contours that extend beyond the limits of the tile.

2.1

(Mar 16, 2006)

• Added a DXF export option. Contour lines are exported to a .dxf file where each contour is a polyline with a corresponding elevation. Might not be fully compatible with some programs, but AutoCAD seems to read the files.
• Added a feature to import irregularly spaced contour levels from a text file.
• Fixed a bug where some contours might not get plotted depending on the refresh interval.

2.0

(Mar 13, 2006)

Nothing dramatically new in 2.0... version numbers are arbitrary!

• Fixed a memory leak when the 'enable bitmap' checkbox was selected during batch operations.

1.9

(Jan 11, 2006)

Note- version 1.8 and later will work best with version 6.2 of the IDL VM. Please download the latest version from RSI.

• Fixed issue with OS X compatibility.
• Added a progress bar and button for aborting processing.

1.8

(August 19, 2005)

• Fixed zoom box display issue. (again)
• Changed help system.

1.7

(July 20, 2005)

• Fixed zoom box display issue.
• Tweaked GUI layout.

1.6

(July 11, 2005)

• Added option for imperial units. Contours can now be generated with spacing in feet or meters.
• There seems to be a problem with the plotting of the zoom box outline while dragging the mouse.

1.5

(Apr 18, 2005)

• Added basic support for UTM projection GeoTIFF files. The output is still Lat-Lon for now. For example, DEM files from http://rocky.ess.washington.edu/data/raster/tenmeter/ can be converted to GeoTIFF by using 3DEM or other software to make them compatible with DEM2TOPO.

1.4

(Apr 18, 2005)

• Fixed bug when loading GeoTIFF files with invalid format.

1.3

(Mar 1, 2005)

• Added a bitmap preview feature to display the DEM before processing. The bitmap will not print in the current version.
• Added a color table selection option to change the color mapping of the DEM elevation. The new dem2topo.tbl file contains the color table information.

1.2

(Feb 11, 2005)

• Added a 'Sea Level Threshold' feature to disregard elevation values below a given value. This is useful if you are contouring a region that has large water areas in it, since the many small reflections from waves can result in enormous numbers of contours.
• Improved the plotting efficiency. Zooming should now be faster.
• Further development and file format support will take place on a 'per-request' basis.

1.1

(Jan 11, 2005)

• Added a button to disable the plot. Complex SRTM files or low contour spacings will result in topos with many thousands of contour lines. For these files, disabling the plotting or increasing the plot refresh time to >30 sec will greatly improve the processing speed.
• Improved the plotting efficiency. Topos with large numbers (>5000) of contours will still plot slowly.

1.0

(Jan 7, 2005)

• Added a settings file so that DEM2TOPO now remembers program settings and the last used data directory.
• Added SRTM .hgt file support. Only the 1 square degree maps will work at the moment. These can be downloaded from ftp://e0mss21u.ecs.nasa.gov/srtm/

0.9

(Jan 6, 2005)

• Improved the efficiency of the contouring code. Large topos with high contour density should be calculated much faster now. Thanks to Dave for noticing the bug.
• Added a feature to skip the contour simplification routine if the simplify factor is set to 0. This might save some time and produce more accurate contours, but the file size may be 10 times larger than if using a simplification factor of 10.

0.8

(Jan 5, 2005)

• Added a entry box for the plot refresh interval. Longer intervals will reduce the amount of time spent undating the display in large topos.

0.7

(November 25, 2004)

• Fixed some minor bugs with the zooming.
• Printing now maintains a 1:1 aspect ratio
• Fixed minor bug in the .mp file generation. File output not affected.

0.6

(November 1, 2004)

• Printing now supported.
• Zooming the display with the mouse now supported. Right mouse button un-zooms.
• **This version may have a few bugs in it. Let me know if it crashes on your system. The plot lines may be blurry on dual monitor displays or odd resolution settings. Use A single monitor desktop with resolution between 1024x768 and 1600x1200 for best results. Plotting may be a bit slower than version 0.5. Download that version if you want speed and stability.

0.5

(October 26, 2004)

• Fixed an issue with southern latitude maps, where values of -10 degrees and larger would not output properly in the .mp files. Thanks to Thomas Jacob for flagging this.

0.4

(April 27, 2004)

• Now reads GeoTIFF files. This has only been tested with the GeoTIFF files created by 3DEM. There are a large number of encoding options for GeoTIFF files, and most will probably not work! If you have a data set that you want to use, email me the format details.
• The 3 and 1 arcsec SRTM data (.hgt files) can be converted into GeoTIFF by 3DEM, and loaded into DEM2TOPO. Note that the 1 arcsec maps can be large. SRTM data for various countries can be downloaded for free at ftp://edcsgs9.cr.usgs.gov/pub/data/srtm/
• Fixed some minor bugs with the axis scaling, etc.

0.3

(April 26, 2004)

• Version 0.3 reduces the complexity of output polylines, at the expense of a little speed. The output file sizes are now smaller by a factor of 4 or more, depending on the 'Simplification Factor'.
• Exporting OziExplorer bitmap and .map files will be an option in the next version..

0.2

(April 23, 2004)

• Polish format support added: DEM2TOPO now generates .mp files as well as ESRI shape files.
  The Datum is written in the .mp file according the the cGPSMapper Datum_List.txt file, but for some reason GPSMapEdit only displays 'WGS 84' in the file properties dialog when these files are loaded.
  The IMG file number is set to an auto-incremented number starting at zero and going to the number of selected files.

0.1

(April 22, 2004)

• Initial Release: DEM2TOPO was written in an afternoon. There are sure to be bugs...

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