Mapping Hacks

Make 3-D Raytraced Terrain Models #20

Chapter 2, Mapping Your Neighborhood

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HACK

Modeling Terrain With POV-Ray

POV-Ray, which is essentially a program for describing a three-dimensional

scene, takes a .pov file as its primary input. The .pov file that we’re using to

generate a simple 3-D map of our terrain is as follows:

camera {

location <0, .25, 0>

look_at <.01, 0, .5>

}

light_source { <0, 3000, 0> color <1,1,1> } // sunlight

height_field {

png "crater_lake_dem.png"

smooth

pigment {

gradient y

color_map {

[ 0 color <.25 .25 .25> ]

[ 1 color <1 1 1> ]

}

}

translate <-0.5, 0, 0>

scale <1, .1, 1>

}

All .pov files contain two important elements: a camera, and at least one

light source. The camera describes the location and orientation of the scene’s

viewing point. By default, the scene is one “unit” wide in any direction,

which is why all our numbers are fractional. The

location and look_at com-

mands place our

camera somewhat above ground level, looking ahead and

down toward the ground. We define a

light_source to be our “sun,” 3,000

units directly overhead—i.e., very far away. Colors are specified as a vector

of red, green, and blue, so

<1,1,1> gives us a white light.

Finally, we define the

height_field as being based on our digital elevation

model, smoothed out (so that the elevation changes aren’t jagged), centered

on the middle of the model, and then scaled so that the peaks stand out rela-

tive to ...