Mapping Hacks

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Chapter 2, Mapping Your Neighborhood

#21 Map Health Code Violations with RDFMapper

HACK

In general, tourist maps, and even many online satellite-derived, vector-

based maps such as MapQuest’s, don’t exactly correspond to the real topog-

raphy of the surface—the area of a park there, the width of a street here, the

shape of a mall elsewhere. Older maps may have measuring discrepancies,

built up over the years, or bits of the topography may have genuinely

changed since they were drawn. The process of taking an old or evocative

map and stretching it so that it matches up with a more accurate base model

is sometimes referred to as rubbersheeting, and it’s a technique that David

Rumsey uses to overlay nineteenth century maps over scenic terrain

[Hack #23].

See “Georeference an Arbitrary Tourist Map”

[Hack #33] for more details about

augmenting the spatial accuracy of non-GIS maps.

As a final note, POV-Ray can even be used to render terrain found in the Solar

System! This very possibility is explored in “Map Other Planets”

[Hack #34].

But wait, there’s more! POV-Ray can also generate succes-

sive frames of “fly-through” sequences, allowing you to pan

and zoom a camera through your rendered terrain. An open

source video encoder, such as mencoder, can then be used to

stitch these frames together into sometimes breathtaking

short animated clips. See http://mappinghacks.com/projects/

povray/ for further exploration ...