Saturday, July 02, 2005

USGS + NG = Topo!

Not any time too soon you will come across National Geographic Topo Maps. A trustworthy distribution of USGS 7.5° Topographic maps.

Your local library might open that door for you.
And you can find on the web for $69 apiece.

With the LT-20 drawing your path over a California State level 5 map you will see your route thru the raster image of your neighborhood. Topo! 3.4.3 engine will show in its best precision a free drawing in between (configurable) GPS obtained location points (waypoints).

Lack of interpolation might show interesting effects, like when I was driving across a private farm (without realizing it) and Topo! zipped through a whole degree and landed its red drawn line miles across the screen while misreading the Receiver.

From Topo Installer Billboard:

GeoTiff support, Professional Topo! Xport Pro, geo-referenced raster images based on Topo maps for use with CAD, cartographic or GIS software, references by lat/long or UTM maps projections, NAD 83/WGS84 or NAD27. Price 199$

[Regarding UTM: above it is used to identify a type of projection, but it also refer to a grid zone.]

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