Using the USGS LCC Data Base in Arc/Info


There are several sources of vegetation data for the United States available on the world wide web. Many of those data sets are referred to in my research documentation. One of the best sources of vegetation data that can be utilized in a GIS is the USGS Land Cover Characteristics data. This data is part of a project to develop one kilometer vegetation data for the entire world. The data can be found at the web site


The U.S. Geological survey is developing this data in cooperation with the the University of Nebraska-Lincoln and the European Commission's DG Joint Research Centre. The data is being generated from 1-km Advanced Very High Resolution Radiometer data. The data for North America is available in two projections and six formats. The data can be obtained in either the Interrupted Goode Homolosine Projection or in the Lambert Equal Area Projection. The most detailed version of the data is referred to as the North America Seasonal Land Cover Region set and has 205 vegetation classifications. These classifications can be found at the LCC Legend.html.


Using the Data in Arc/Info

Although this data base is public domain, the conversion of the data to an Arc/Info usable format is not completely obvious. The following is the process that I used to make the vegetation data useable in Arc/Info.


  2. Arc/Info directly supports the Lambert Azimuthal Equal Area projection so it is more convenient to use the data in this projection (especially if the coverages are to be projected into other coordinate systems). Once the desired data set is decided upon the file can be either downloaded off the web directly from the North American Land Cover Lambert Azimuthal Equal Area Projection File Listing found at or it can be obtained via ftp from ftp in the directory /pub/data/glcc/na. The files are on the order of 83 megabytes so gziped files are available.

  4. The files are of .img format which is easier to use with some programs than others. There is a public domain program called ____ which can be used to view these images and can be obtained from NASA's web site (although time was not used to learn this application).

    To use the data in Arc/Info the data must be converted from the .img format to a grid. First the file should be unzipped if the zipped version was downloaded. The unzipping comand in a UNIX environment is as follows.

    gunzip <lcc.img>

    Next the file needs to be given a "bil" extension.

    mv <lcc.img> <lcc.bil>

    Then a header file needs to be made for the bil file. This header file contains information on the size and location of the data set. The file can be made in any type of text editor, but it needs to be saved in the same directory as the 'bil' file and have the same name as the bil file.


    The metadata needed for the header files can be found at under geometric characteristics. The header file created for the Seasonal Land Cover data set was as follows (words in parenthesis are only for explanation, do not use in actual file).



    (Number of rows in the data set)



    (Number of columns in the data set)



    (The bit size of the image 0



    (The x-coordinate of the upper left corner of the image)



    (The y-coordinate of the upper left corner of the image )



    (Number of meters in x direction for each pixel)



    (Number of meters in y direction for each pixel)


    There should now be at least two files in the working directory; <lcc.img> and <lcc.hdr>.


  6. Now in arc convert the bil file to a grid file using the IMAGEGRID command.

    Arc: imagegrid lcc.bil lcc



Use arc to update the information on the projection using the PROJECTDEFINE command.

Arc: projectdefine lcc

Project: projection lambert_azimuthal

Project: parameters

radius of sphere of reference [0.00000]: 6370997

longitude of center of projection [0 0 0.000]: -100 0 0.000

latitude of center of projection [0 0 0.000]: 50 0 0.000

false easting (meters) [0.00000]: 0.00000

false northing [0.00000]: 0.00000

(all of the above projection parameters for my file were taken from the Lambert Azimuthal Equal Area Projection Parameters found at These may change depending on the dataset being used.)



Up to this point the data in the working directory is for the entire North American Continent. If only a small section of this file is needed, processing time can be saved if that area is isolated. The Arc/Info functions found in Grid are useful for isolating that area.

The first step is to identify the area that is to be isolated on the grid of North America. Go into Grid in Arc to view the file.

Arc: grid

Grid: display 9999 (opens a viewing window)

Grid: mapextent lcc (sets the range of the window to that of the file)

Grid: gridpaint lcc (paints the file in color, use gridpaint lcc value linear nowrap gray for a gray image, and clear to erase any image)

Now the area of interest must be selected from the file. Water landmarks can be used for orientation in the file. The AVHRR value read for all water is the same and is shown in black in this display. Either lakes or the shoreline of the continent can be used to locate the desired domain. When in doubt always allow for extra area that can be removed later. The user interface on the view window will let you zoom in and out in the file if more detail is desired. Now separate the region of interest.

Grid: setwindow * (This will let the user draw the borders of a rectangle which will be the area of the new file. Use the curser in the image window and click the mouse button to make two opposite corners of the selection rectangle.)

Grid: lcc2=lcc (Creates and names the smaller grid)

Grid: clear

Grid: setwindow lcc2

Grid: gridpaint lcc2

You should now see a much smaller and more convenient file. The process can be repeated if needed (The clip command in Arc can also be used later).


  2. The grid file that is now in the working directory does not have an attribute tale at this point. The only data that this file contains is the numerical value that represents the land cover type for each separate square kilometer. There are a couple of ways to complete the attribute table for the file depending on the software available to the GIS technician. One method is to use Info. Another is to use Arcview if that program is available.


    The following is a general outline of the procedure for attaching the attributes to the file using the Info options in Arc/Info. (It were provided by Mr. John W. Jones of the U.S. Geological Survey)
    1.) using info, create a table that will be used to hold the attribute information: define lcc.inp
    2.) use an editor to reformat the attribute file (lcc.att) for import to info. I used commas to delimit the fields, placed the character strings in quotes, and removed all blank spaces (excepting those in the strings).
    3.) in info, "add" the data from the ascii file into the info table:
    add from /home/GISuser/lcc.dat
    4.) in arc, use "joinitem" to put the fields in lcc.inp into the vat file for the lcc2 grid:
    joinitem lcc2.vat lcc.inp lcc2.vat value count
    The grid should now be ready for use. If a polygon coverage is desired the grid can be converted using Arc:
    Arc: gridpoly lcc2 lcccoverage
    For the arcview method the grid is just converted to a coverage and then the additional information can then be manually added into the coverage's attribute table.
    Arc: gridpoly lcc2 lcccoverage
    Arc: clean lcccoverage
    lcccoverage can now be brought into arcview and the attribute table can be modified using the table editing features. Start a new file in arcview. Open a view in arcview and bring lcccoverage into it from where it is being stored. Then click on the attribute table button in the Arcview GUI (graphical user interface). Go to 'edit table' in the edit menu. Then go to 'add field'. Name the field, indicate characters because words will be used in this attribute, and make the size of the columns large enough for the descriptions to be used. The descriptions can be determined by looking at the legend for the file being used. Now select 'add rows' for data entry into the table. Click on the hand symbol over the table and then on the places to enter data. Once the table is completed make sure that none of the cells are raised and select 'stop editing' under edit.
    Another option in Arcview is to just use the attribute table with only the value field in it, but to design and store a legend with the corresponding descriptions in it.
The coverage can also now be projected into another coordinate system if needed (UTM coordinates for example). See projecting into UTM coordinates for an example.