When you have a raster dataset, you may need to find the basic information about it:
- Format—This is the file type used to store the raster. Different file types have different properties and requirements.
- Number of bands—This is the number of spatially coincident layers in the raster. Rasters have at least one and may have hundreds.
- Data type—The data type, also known as pixel type, pertains to the type of values stored in the raster, such as signed integer, unsigned integer, or floating point. Integers are whole numbers, whereas floating points have decimals.
- Data depth—The data depth, also known as pixel or bit depth, determines the possible range of values stored in each band. A depth of eight will store 28 = 256 values (0 to 255), while a depth of 16 will store 216 = 65,536 values (0 to 65,535).
- Statistics—These include the minimum value in the raster, maximum value, mean of all values, and standard deviation.
- Extents—These are the left, right, top, and bottom coordinates of the raster dataset.
- Projection—This is part of the raster's coordinate system and can be found in the Spatial Reference section. An <Undefined> raster may mean it's not projected, or it could mean that it is just not yet defined. Check with the data vendor to verify the raster's correct coordinate system.
- Size of the raster—This could mean the number of rows and columns or the uncompressed size.
All this can be found on the Raster Dataset Properties dialog box. In ArcCatalog, right-click the raster datasets and click Properties.
If you want to see the amount of disk space taken up by the raster, open Windows Explorer, right-click the raster file, click Properties, then look at both Size and Size on disk.
Other information you may be interested in can include questions such as the following.
- Where did the raster come from?
- What does the data represent?
- What is the purpose of the data? What will it be used for?
- Was there any special processing used to create the raster?
- History of the raster: what has been done to it?
This information can be found in the raster dataset's metadata; however, it will only exist if someone has entered it.
To access the metadata in ArcCatalog, click the raster dataset and click the Metadata tab.