Map Design

Utilizing MicroCAM to its full potential presupposes that the user has a good grounding in cartography. It is not the purpose of MicroCAMs on-line help to serve as a cartographic primer. Familiarity with CAM, though not required, should assist you in using MicroCAM.

The MicroCAM command set can be divided into two categories: those that set program mapping parameters (called data words in CAM) and those that draw some feature of the map (called command words in CAM). You should set all desired mapping parameters values prior to the first drawing command. When MicroCAM encounters the first drawing command in a command file, it initializes the projection with either the default parameters or those specified previously in the command file. The order of specifying the mapping parameters is not important as long as all desired values are set prior to any drawing commands. The following steps provide a logical progression in the map design process:

Choose the output media
size and orientation.

MicroCAM can create maps on any standard size media or a size you specify using the SHEET command. The default is landscape orientation on 11 x 8� paper with a neat line of 10" by 7-�" which leaves a �" margin on all sides of the sheet. These limits may be changed using the XYLIM command. There is no visual indication of the sheet limits other than the line implied by the clipping of features drawn outside of the limits. You may use the BOXXY command to draw the neat line, but this command should appear after all lines setting the mapping parameters because the first drawing command initializes the map.

Select a projection.

This, of course, is not a trivial decision. Generally, there are at least two considerations that should influence your choice of projection: map area (scale) and purpose. Table 1 can be used as a basic guide to the applicability of the projections in MicroCAM based on their properties.

Some of the projection commands require additional parameters specifying details such as standard parallels, central meridians, etc. This may be easier to do after you determine the center point and map boundaries as described in the next step.

Set map center point,
geographic limits and scale.

The center point of the map is set with the CETPOT command. This geographic point will be plotted at the center of the map sheet with the balance of the map plotted around it. Next, determine the geographic limits that you want your map to include. This is usually quite straight-forward for a small scale map (e.g., world or hemisphere) as you can select the bounding parallels and meridians which will generally fall within the sheet limits. The limits are set with the MAPBOUND command so a world map centered on 75 degrees west would have:

CETPOT 0,,,-75,, MAPBOUND -90,,,90,,,75,,,75,,

Note that MicroCAM will understand this command even though the same minimum and maximum longitude are specified. The map boundaries are correctly interpreted as 90,,,90,,,255,,,75,, (which is also a legitimate specification). For medium to large scale maps where the feature detail will extend to the sheet limits, choose bounding parallels and meridians sufficiently large to include all desired feature areas and also large enough to avoid lines being clipped short of the sheet limits. For example, on a northern hemisphere conic projection, it may be necessary to extend the longitudinal limits because convergence of the meridians will make the plotted geographic area much narrower at the top of the sheet.

The map scale is set with the MAPSAL command. This must usually be done iteratively. Select an approximate scale using the following guide:

World maps
Hemisphere maps
Continental maps
Regional maps

1:160,000,000
1:80,000,000
1:45,000,000
1:25,000,000

Some projections (AZED, AZEQAREA, HAMMER, MOLLWEID, PERSP, POSTEREO, STEREO) use the MAPSAL command to set the radius of the projection circle. This is difficult to relate to the final map. Try 1-3 as an initial value. Run the command file and note whether the map displays the area of interest at the desired scale. Adjust the scale up or down as necessary. If you include an LGRID command as the first drawing command in your file, it will give you a good frame of reference for verifying the map scale.

Add a graticule, if desired.

A graticule, a latitude/longitude grid, is a feature of most maps. It allows the map user to determine geographic locations on the surface of the earth. MicroCAM provides two commands to draw graticules. The first, LGRID draws a grid over the range of latitude and logitude you specify at an interval you also set. LALOTICK draws a tick mark at each intersection of a grid, but the full grid is not drawn.

Choose the maps features.

MicroCAM has six standard databases suitable for mapping at scales as large as 1:3,000,000. These World Data Bank II - derived files provide coastlines, islands, lakes, rivers, international boundaries and state boundaries. The standard database files are accessed with the FEATURE and LINEPT commands. For the United States, more detailed US Census Bureau files are available for each state that include the county borders. The state files are accessed with the LINEFILE command. Similar enhanced detail for other borders missing from the basic WDBII database is available for the Canadian provinces, Caribbean island nations, Commonwealth of Independent States, and the MiddleEast. These databases are also accessed with the LINEFILE command. Countries of the world may be added by name using the LIBRARY command and library database files. Higher resolution mapping can be done with the packed format WDBII files and the PKDFILE command. You can also draw geographic features using USGS digital line graph files (or files in the DLG format) and the DLGFILE command. Digital Chart of the World (DCW) data may be drawn using the DCWFILE and DCWTEXT commands. Any feature drawing command should be preceded by LINEWT, LINEMODE and PEN commands as desired to set the appropriate line type and color to be used.

Many mapping commands set the characteristics of the map and should be set before any feature drawing commands. These include:

AXIS, CALIB, CLIP, CONFAC, DB2PLOT, EATRAD, ECCENT, FONT, GEOFFSET, ORGOFF, PLOTTER, REVRSXY, ROTATE, SCRIBE, STEP, SUPPRESS, TSLAT and XYOFF.

Add additional drawing commands.

To complete the map, you will want to add other drawn features such as titles and symbols. Again, drawing commands should be preceded by LINEWT, LINEMODE and PEN commands as desired to set the appropriate line type and color to be used. Additional drawing commands include:

1, ARC, ARCXY, BODE, BOX , BOXXY, BRANGE, CENTERTK, CIRCLE, CIRCLEXY, CORNERTK, ELIPSERG, ELLIPSE, ELLIPSXY, FILL, FILLXY, GEOLINE, GRDCIR, GRDCIRXY, GTCIRCLE, LINE, LINEXY, OPENBOX, REGISTK, RRANGE, SHADE, SHADES, SHADEXY, SYMBOL, SYMBOLXY, SYMPT, TEXT and TEXTXY.

Congratulations, you have designed a map with MicroCAM for Windows!

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