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\title{Planetary Terrain Rendering}

\titlerunning{Lecture Notes in Computer Science}

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\begin{abstract}

Visualizing planetary terrain presents unique challenges not found in
traditional terrain visualization: displaying features that rise from
behind the horizon on a curved surface; rendering near and far surfaces
with large differences in scale; and using appropriate map projections,
especially near the poles. Projective Grid Mapping (PGM) is a hybrid
terrain rendering technique that combines ray casting and rasterization
to create a view-dependent mesh in GPU memory. We formulate a version
of PGM for planetary terrain that simplifies ray-sphere intersection to
two dimensions and ray casts the area behind the horizon. We minimize
the number of rays that do not contribute to the final image by creating
a camera that samples only the area of the planet that could affect the
final image. The GPU-resident mesh obviates host-to-device communication
of vertices and allows for dynamic operations, such as compositing
overlapping datasets. We adapt two map projections to the GPU for
equatorial and polar data to reduce distortion. Our method achieves
realtime framerates for a full-planet visualization of Mars.

\end{abstract}
