Mapping Hacks

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Chapter 5, Mapping with Gadgets

#53 Visualize Your Tracks in Three Dimensions

HACK

Once you start the program, you need to set an “area of interest.” You can

do this in one of three ways. Select View

➝ Pick Center to manually enter a

point to be the center of your map. Alternatively, you can connect a GPS to

your system and read points directly, or you can load a waypoint from a

GPX file.

If you open a GPX file, the program will fetch aerial photos or topo maps

from Terraserver and plot your tracklog over the image, once you’re zoomed

in close enough. You can select a USGS topographic base map (i.e., a DRG)

with File

➝ JPG Topo Basemap, or an aerial photo base map with File ➝ JPG

Photo Basemap. Figure 5-10 shows a GPX tracklog from Black Rock City,

Nevada laid over an aerial photo automatically downloaded from

Terraserver.

Loading New Elevation Models

Wissenbach Map3D uses USGS DEM files, each of which covers a seven-

minute named quadrangle (about 8 miles by 6.5 miles) at a resolution of one

arc second (~30m) or one-third arc second (~10m). The 30-meter DEMs

are plenty good enough to experiment with at first, and they involve down-

loading a lot less data than the 10-meter DEMs. Later, if you really get into

playing with digital elevation models, you can go back and get the 10-meter

DEMs.

Figure 5-9. The Yosemite Falls trail shown in Wissenbach Map3D

Visualize Your Tracks in Three Dimensions #53 ...