Help Page for MrSID Image Format Files
MrSID is a proprietary data format that allows image files to be substantially compressed with little to no
loss of image quality. This format, developed and marketed by LizardTech, Inc., allows
you to view any portion of a MrSID image at any resolution very quickly.
The name stands for "MultiResolution Seamless Image Database."
You may look at MrSID files with your web browser or with many geographic information systems (GIS) software packages.
- Plug-in for web browsers (free)
If you want to see MrSID images using a web browser such as Internet Explorer, Firefox or Chrome (Windows versions), use LizardTech's ExpressView Browser Plug-in. It is free for individual use; download it and follow the installation wizard instructions.
Once you've installed the plug-in, use Windows Explorer to find a MrSID file on your computer, and then double-click on the filename to automatically open a browser window displaying the file. Alternatively, you can view a MrSID image that has been posted on a website without having to save the image on your computer. Use the buttons at the top of the plug-in window to zoom in and out, pan across the image, return to the full image, check the image properties and find help.
- Standalone application
LizardTech also provides a Windows standalone application called GeoExpress View that provides a number of functions not available in the ExpressView Browser Plug-in. See the GeoExpress View page for an overview of features and to download a free trial version.
- Esri's ArcGIS software
The software comes enabled to view MrSID files. For more details, search for the keyword "MrSID" in ArcGIS Help.
Tip: If your MrSID image is composed of more than one band, you can display either the composite image or any individual bands. (For example, NAIP 2003 natural color imagery is composed of three bands: Band 1 = red; Band 2 = green; Band 3 = blue.) To see the composite, choose "Add Theme" and make sure you have selected the image name (not the individual band names that appear as "subdirectories"). This will add all the bands and will display them with whatever red/green/blue color assignments are set under the Tools/Options/Raster menu. To see individual bands, click on a band name (e.g., "Band 1") that appears listed under the image name. They will display either in black-and-white or just in one color such as red. Note that in ArcMap, if you double-click on the image name when you add a theme, you will open a listing of the bands and may inadvertently add the individual bands instead of the composite. If this happens, remove the individual band themes and repeat the "Add Theme" steps using just a single-click.
- Other GIS software
Many other GIS packages have the ability to view MrSID images already built-in. If it is not built-in, check the LizardTech Software Download page to see whether there is a plug-in specifically for your software package.
Many users of Minnesota GIS data would like to display MrSID files from one UTM zone with other files that are in another UTM zone.
- See a map from the Minnesota Department of Transportation that shows the boundaries of UTM Zones 14, 15 and 16 in Minnesota.
- Note that many GIS files
available in Minnesota are in Zone 15 extended to cover the entire state.
Reproject using GeoExpress software
LizardTech's GeoExpress Tools software will reproject MrSID
format files. For more information and to download a trial version, see
Display using ArcGIS software
ESRI's ArcGIS software will display MrSID files in another zone -- this method does not change the file itself, just the display. Note that the following instructions assume that you know which zone the file is in and that all of the data files are in the NAD83 datum.
1. Set the projection for each file
The method for setting the projection varies depending on the file type:
- MrSID projection information is held in an auxiliary file (.aux extension).
- Make sure the .sid file is not marked "Read-only" since ArcCatalog will not save an auxiliary file in the same folder as the data if it is. (In Windows Explorer, right-click on the filename and choose "Properties" -- uncheck the "Read-only" box if it is checked.)
- Open ArcCatalog and navigate to the MrSID file. Right-click on the filename and choose "Properties."
- Choose the "Spatial Reference" tab and then click the "Edit" button.
- Click "Select..."; "Projected Coordinate Systems"; "Utm"; "Nad 83"; "NAD 1983 UTM Zone 14N.prj" (for Zone 14 files), "NAD 1983 UTM Zone 15N.prj" (for Zone 15 files) or "NAD 1983 UTM Zone 16N.prj" (for Zone 16 files)
- Click "OK"; "OK"
- Note that if you move the MrSID file to another location, you need to also move the .aux file with the same name, otherwise you'll have to reset the projection.
- Shapefile projection information is held in a projection file (.prj extension).
- If a shapefile does not already have a .prj file, you can create one in ArcCatalog. For the procedure, check ArcGIS Help: in the Help "Contents" tab, look under "ArcCatalog"; "Working with shapefiles"; "Defining a shapefile's coordinate system."
Coverage or ArcGrid
- Projection information for these file types is held in a projection file (prj.adf in the coverage or grid directory).
- If a coverage does not already have a prj.adf file, you can create one in ArcCatalog. For the procedure, check ArcGIS Help: in the Help "Contents" tab, look under "ArcCatalog"; "Working with coverages"; "Defining a coverage's coordinate system."
2. Display the files in ArcMap
- Now open ArcMap. Add a file that is in the UTM zone you want to use. Then add the other files. All the files should now display in the same zone as your first file.
- Note that the order in which you add the files is important since the first
you add establishes the projection for the
display view. For example, if a Zone 15 file was added first, subsequent
files would also be displayed in Zone 15.
See LizardTech's webpage:
Decoding a MrSID file to other formats