The NTDB (National Topographic Database) is a multi-layered vector
dataset. In this example, I used only the hypsography layer.
With the GRASS tool v.to.rast I changed the vector layer into
a raster layer that showed the contour lines, with random colours
assigned to each line, and whitespace between contour lines. Using
r.surf.contour I then made a DEM (digital elevation model)
raster layer in which cell colours were assigned by interpolation
between the contours.
Using r.slope.aspect I made two more raster layers in which
cell values were associated with slope and aspect. And I made an IHS
raster layer using r.his, i.group and i.composite.
The DEM raster layer gave the hue values and the aspect raster layer
gave the intensity values in the resulting map.
Finally I displayed the IHS layer draped over the DEM using d.3d.
In this view, you are at 7000' looking northeast across the Ark Mountain
quadrangle. Kusawa Lake is the black "water" in the rightmost
valley.