/usr/share/osgearth/maps/fractal_detail.earth is in osgearth-data 2.5.0+dfsg-2.
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osgEarth Sample - Fractal detail
Uses the noise driver to add fractal detail to the terrain,
making it appear higher resolution than it really is.
This can be useful for presentation purposes when you don't
have very high resolution data.
-->
<map version="2">
<!--
Start with the ReadyMap elevation as our basis.
-->
<elevation name="readymap_elevation" driver="tms" enabled="true">
<url>http://readymap.org/readymap/tiles/1.0.0/9/</url>
</elevation>
<!--
Set the frequency to be the reciprocal of your elevation resolution.
i.e., if your elevation data is 90m, set freq = 1/90. That will cause
the noise function to cycle every 90m. This means you will only get
noise between your real elevation values.
Within that 90m span, the noise function will generate values between
[0..scale]. So if the scale=10, you will get up to a +/-10m variation in
elevation at each interpolated point eithin the 90m span.
Octaves controls the recursion of this operation. The noise function will
run once as normal, then again to further refine the results of the first
output, and so on.
With each succesive octave, the output is scaled like this:
freq *= lacunarity, and scale *= persistence. This happens successivly for
each octave.
-->
<elevation driver="noise" name="noise" enabled="true" offset="true">
<tile_size>31</tile_size>
<frequency>0.004</frequency> <!-- one cycle every 250m -->
<lacunarity>2.0</lacunarity> <!-- freq *= lac for each octave (default = 2) -->
<persistence>0.5</persistence> <!-- amp *= pers for each octave (default = 0.5) -->
<octaves>4</octaves>
<scale>20</scale>
<bias>0</bias>
</elevation>
<options>
<elevation_tile_size>31</elevation_tile_size>
<elevation_interpolation>bilinear</elevation_interpolation>
<terrain min_lod="16"/>
</options>
<external>
<contour_map/>
</external>
</map>
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