HELP PAGE -- images in the Map Catalog
II. Viewing the maps
a. Without a plug-in
b. With the ExpressView Browser Plug-In
III. Downloading a map image
IV. About MrSid files
a. General
b. MrSid Decode Tool
V. Georeferencing an image
VI. Information for contributors
Return to Map Catalog
I. About the map images
The Geoscience Map Catalog includes viewable images of selected geologic and related geoscience maps (e.g., of landslide potential). These map images were obtained by scanning the paper map and creating a full color, 300 dpi TIFF file, or by converting the digital file (e.g., in PDF format) to TIFF. These files then were converted into MrSid format (20:1 compression) in order to provide them to you quickly and easily via our map viewing interface, the LizardTech Content Server.
We are working steadily to convert as many maps as possible into viewable images. If you would like to contribute to this library of map images, please contact us!
II. Viewing the maps
We offer two options for viewing these map images online (see example). One requires a plug-in for your web browser and the other does not. Both methods allow you to view, zoom, and pan so that you can clearly read the maps on the screen. The method you choose will depend on your computer platform and Web browser.
a. Without a plug-in
By choosing Option "2", you can view the map without using a plug-in. Rudimentary zoom and pan capabilities are available.
b. With the Express View Plug-In
Option "1" provides a more advanced zoom and pan function, but requires the LizardTech Express View plug-in for your Web browser. Help for this plug-in is available, or you can access the help option by clicking the "question mark" icon in the upper right corner of the viewing interface. This plug-in has some useful viewing options -- for example, by right-clicking on the image you can view the map in full-screen, and optimize your screen dimensions to view more of the map at once. The plug-in has produced mixed test results when used with with low bandwidth, dial-up connections.
This plug-in has the following system requirements:
For Windows:
Microsoftš Windows 2000/XP or Windows NT 4.0 with service pack 6 or greater
200MHz PC processor
Minimum of 64 MB RAM
Netscape 7.x and greater or IE 5.5 and greater.
For Macintosh:
Apple Mac OSX 10.3
Minimum of 128 MB RAM
Safari Web Browser
III. Downloading a map image
To download a map, find the "download image" link on the image viewer page. Right-click on the link and choose the "Save Target As . . ." option. Save the file with a suitable file name to your chosen location in MrSid format (mapfilename.sid).
IV. About MrSid files
a. General
"MrSid" is the Multi-resolution Seamless Image Database format. This compression format was first developed at the Los Alamos National Laboratory (LANL) and is now provided by LizardTech Software, Inc. The format compresses images so that are more easily accessed over the Internet, without a noticeable loss in detail. For technical information please visit the Lizardtech website, http://www.lizardtech.com.
The Web browser plug-in enables you to view the MrSid file through our system, and it also permits you to view the file locally, if you choose our "download image" option. LizardTech offers free viewers for several GIS packages such as ArcGIS and Caris, and a stand-alone image manipulation package called the GeoViewer which can be downloaded from LizardTech on a trial basis -- these are further described on the LizardTech Download Site
b. MrSid Decode Tool - converting MrSid to other formats
By using the MrSid decode tool, you can decompress a MrSid image and use it in software programs such Adobe Illustrator and Photoshop. The decode tool is available for Windows, Linux, and Solaris operating systems. The following instructions will help you understand how to use this tool in the Windows environment. Additional platform-specific instructions will be included with your download.
1. Extract the mrsid decode .zip file to some location, such as your C: drive, creating the folder C:\mrsiddecode_win
2. Open a dos prompt, "cd" into the folder where the mrsiddecode.exe file is located. For example "cd C:\mrsiddecode_win"
3. Save the MrSid image you downloaded to: C:\mrsiddecode_win. For example, if you have just downloaded The Geologic Map of the Table Mountain Quadrangle, save the downloaded file "q24_993_us_1.sid" into C:\mrsiddecode_win
4. Assuming you are already in c:\mrsiddecode_win, type:
"
to convert the image to TIFF format.
5. Here are other examples from the mrsidgeodecode_readme.txt file found in the C:\mrsiddecode_win folder
* To decode a MrSID file to a JPG file:
mrsidgeodecode -i input.sid -o output.jpg
* To decode a MrSID file to a GeoTIFF file:
mrsidgeodecode -i input.sid -o geotiff.tif -of tifg
* To decode the upper-left 50x50 pixel scene from a MrSID image:
mrsidgeodecode -i input.sid -o output.tif -ulxy 0 0 -wh 50 50
* To decode an image at scale 2, i.e. one-quarter resolution:
mrsidgeodecode -i input.sid -o output.tif -s 2
6. For further help with mrsiddecode, type "mrsidgeodecode -help"
V. Georeferencing an image
Some files contain georeferencing information in "world" files that you can choose to download with the map. Maps without this georeferencing information can be registered by using the bounding coordinates for each map or benchmarks printed on the maps and displayed on the Map Catalog's Product Description Page. Consult the documentation of your GIS software if you wish to register the map image with other spatial data.
NEW!ArcGIS users may wish to download the sample data found in our online georeferencing tutorial.
VI. Information for contributors
We encourage you to work with us, to increase the number of viewable map images available. For information, please see our help page, and contact us.
| U.S. Department of the Interior, U.S. Geological Survey, Reston, VA, USA URL http://ngmdb.usgs.gov/ImageLibrary/help.html Database project personnel. Last Modified: August 3, 2006 USGS Privacy Statement |
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