- West, East, South, North: All coordinates are decimal (-180.00° to 180.00° and -90.00° to 90.00°, respectively).
- Cylindrical Equidistant
- Cylindrical Equal-Area
- Cylindrical Stereographic
- Resolution: Selects the resolution of the data set to use ((f)ull, (h)igh, (i)ntermediate, (l)ow, and (c)rude). The resolution drops off by 80% between data sets.
- Scaling: Selects image size in dpi (2 - 400).
- Minimum Area: Features with an area smaller than Minimum Area in km² will not be plotted.
- Shorelines: The level/pen of shorelines (empty for no shorelines, command can be repeated seperated by spaces). To set the pen for each level differently, prepend level/, where level is 1-4 and represent coastline, lakeshore, island-in-lake shore, and lake-in-island-in-lake shore. When specific level pens are set, those not listed will not be drawn.
- Boundaries: The type/pen pair of political boundaries (empty for no boundaries, command can be repeated seperated by spaces). The type is one from the following list.
- 1 = National boundaries
- 2 = State boundaries within the Americas
- 3 = Marine boundaries
- a = All boundaries (1-3)
- Rivers: The type/pen pair for rivers (empty for no rivers, command can be repeated seperated by spaces). The type is one from the following list.
- 1 = Permanent major rivers
- 2 = Additional major rivers
- 3 = Additional rivers
- 4 = Minor rivers
- 5 = Intermittent rivers - major
- 6 = Intermittent rivers - additional
- 7 = Intermittent rivers - minor
- 8 = Major canals
- 9 = Minor canals
- 10 = Irrigation canals
- a = All rivers and canals (1-10)
- r = All permanent rivers (1-4)
- i = All intermittent rivers (5-7)
- c = All canals (8-10)
- Lakes: The fill for lakes (empty for no lakes (default defined by Wet Areas)).
- Dry Areas: The fill for "dry" areas (empty for no dry areas).
- Wet Areas: The fill for "wet" areas (empty for no wet areas).
- Color Palette: The color palette defines the colors applied over a z-range. Using the RGB system, the format of a color palette is
z_0 R_0 G_0 B_0 z_1 R_1 G_1 B_1 z_2 R_2 G_2 B_2 z_3 R_3 G_3 B_3 ... z_n-2 R_n-2 G_n-2 B_n-2 z_n-1 R_n-1 G_n-1 B_n-1
- Azimuth: Azimuth is the angle in the x,y plane measured in degrees positive clockwise from north (the +y direction) toward east (the +x direction). The negative of the directional derivative, -[dz/dx*sin(azim) + dz/dy*cos(azim)], is found; negation yields positive values when the slope of z(x,y) is downhill in the azimuthal direction, the correct sense for shading the illumination of an image by a light source above the x,y plane shining from the azimuthal direction. Optionally, supply two azimuths, azimuth/azimuth2, in which case the gradients in each of these directions are calculated and the one larger in magnitude is retained; this is useful for illuminating data with two directions of lineated structures, e.g. 0/270 illuminates from the north (top) and west (left).
- Normalization: The actual gradients g are offset and scaled to produce normalized gradients gn with a maximum output magnitude of amp using a cumulative Laplace distribution yielding gn = amp * (1.0 - exp(sqrt(2) * (g - offset)/ sigma)) where sigma is estimated using the L1 norm of (g - offset) if it is not given.