Mapping Hacks

Map Wardriving (and other!) Data with MapServer #92

Chapter 8, Building the Geospatial Web

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HACK

File Bounds: ( -122.155, 37.459,0,0)

to ( -122.091, 37.493,0,0)

Shape:0 (Point) nVertices=1, nParts=0

Bounds:( -122.091, 37.459, 0, 0)

to ( -122.091, 37.459, 0, 0)

( -122.091, 37.459, 0, 0)

Shape:1 (Point) nVertices=1, nParts=0

Bounds:( -122.155, 37.493, 0, 0)

to ( -122.155, 37.493, 0, 0)

( -122.155, 37.493, 0, 0)

$ dbfdump myshape

name

NoCat

QueenFleeWee

Note that shpadd expects longitude first, not latitude!

Remember that the x-coordinate comes before the y-coordi-

nate, where longitude is measured along the x-axis. As usual,

coordinates west of Greenwich and south of the equator are

given negative values.

MapServer more or less requires you to provide the geographic extents of

the area you want to map. If you were creating a map file from the previous

example, you would take your extents from the

File Bounds section, and

your extent line would look like this:

EXTENT -122.155 37.493 -122.091 37.459

You can also check a shapefile’s extents with ogrinfo, a utility included with

the GDAL library. The command

ogrinfo -al -summary myshape will show

the metadata from all layers in a shapefile. See “Convert Geospatial Data

Between Different Formats”

[Hack #68] for more on the OGR and GDAL

utilities.

From Wardriving to Shapefiles

Netstumbler, the network scanning software I use, supports a logging for-

mat called