Graphical Locater Custom Zoom Maps

The Graphical Locater Custom Zoom program creates a square, custom Graphical Locater map that is centered on the last selected location. See the Graphical Locater custom Mapper for non-square custom maps that are defined by limits of latitude and longitude. The custom zoom option is available on all Graphical Locater result pages right after the fixed zoom options. The custom zoom form accepts 10 inputs as well as "submit" and "reset". All inputs, except for the map radius, have default values.

  1. Map radius: This is the distance from the center of the map to any edge in the primary directions (North, South, East or West). There is no default. If the circle and buffer option is used (see below) the map radius is the radius of the circle, the map radius itself, will be larger depending on the buffer used. The map radius can be input as either kilometers or miles. The total map radius (including the buffer) must be at least 1 km and cannot exceed 999.999 km. The map radius combined with the the map center, must not put the map limits outside the NW quarter of the earth.

  2. Map Radius Units: This can be either km or mi. The default is km. The radius itself must exceed 1 km (see above).

  3. Circle and buffer zone: There are 5 options, none and 4 buffer sizes. The default is none. When selected, the map radius is increased by the percentage given by the buffer size and a circle is drawn at the original map radius. This can be useful for spatial orientation.

  4. Mark the center: There are 2 options, yes or no. The default is yes. If the center is not marked you will not be able to get the distance from the marked point on subsequent requests to Graphical Locater.

  5. Roads: There are 6 levels available. The default is for all roads. These data will be 1:100,000 TIGER/LINE data or 1:2,000,000 DLG data depending on the map area.

  6. Water: There are 5 levels available. The default is for all water features. These data will be 1:100,000 TIGER/LINE data or 1:2,000,000 DLG data depending on the map area. Lakes will not be filled for the TIGER/LINE data. For the DLG data, only very large lakes (or parts) will not be filled.

  7. Political: There are 3 options, states, counties or none. The default is none. These are 1,2,000,000 DLG data and may be crude for small area maps.

  8. HUC lines: There are 5 options, the 4 HUC levels or none. None is the default. Theses data were created for our own HUC project based on USGS 1:2,000,000 data.

  9. Background: There are 2 choices, flat or shaded relief. The shaded relief is based on either the 3 second DEM data for 1:100,000 maps or the 1 km DEM data for 1,2,000,000 maps. The shaded relief based on the 3 second DEM will become crude as the pixel size falls below 50 meters. The shaded relief based on the 1 km DEM will become crude as the pixel size falls below 500 meters.

  10. Image size: There are 5 options. The default is medium. The pixel size (in meters) depends on the map area and the image size.
    1. tiny is 400 pixels on each side (0.16 Mega pixels)
    2. small is 600 pixels on each side (0.36 Mega pixels)
    3. medium is 800 pixels on each side (0.64 Mega pixels)
    4. large is 1000 pixels on each side (1.00 Mega pixels)
    5. huge is 1250 pixels on each side (1.56 Mega pixels)
    The actual size of the gif file will vary greatly depending on the image complexity.

Graphical Locater Custom Map Check

This page reports some basic information on the map that is about to be made. An error occurs if the total map radius is not between 1000 and 999999 m, or if any of the map limits fall outside the NW quarter of the earth. The map area limits, size, source data, image size and pixel size are all reported. This information should allow others to use these maps in GIS or as graphics base maps. All Graphical Locater maps are projected as straight latitude and longitude. Note that the shaded relief will become crude as the pixel size becomes small relative to the DEM spacing (100 m for 1:100,000 data and 1 km for 1:2,000,000 data). You can use a larger area and/or a smaller image size to correct this problem.
09 AUG 2001, updated on 10 AUG 2001 D.L. Gustafson
dlg@rapid.msu.montana.edu