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."
For more information, see LizardTech's
GeoExpress Product Overview.
You may look at MrSID files with your web browser or with many geographic information systems (GIS) software packages.
For more details, search for the keyword "MrSID" in ArcView
Help. Other questions may be answered at
ESRI's Support Center website.
ArcGIS 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.
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.
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 (version 8 or 9) 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
LizardTech, Inc. provides a free command-line tool called "mrsidgeodecode"
which can be used to decode .sid images to TIFF, JPEG and other formats.
There is a version for Windows users and one for Mac users. For more
information and links to download the tool, see: