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Forms of Digital mapping
1. Raster maps: Hema
maps are in raster format, covering popular destinations
and tourist areas around Australia. This mapping
is derived from field work, and prepared for either printing
or for digital reproduction, and is called raster
mapping. (Raster, because it is made up of collections
of pixels, or is a bitmap).
Raster mapping has the advantage
of reproducing exactly what we see on paper, including
shading, colouring, features
and contour lines. Raster maps are one scale only, you cannot
decrease the scale without losing resolution, because the
image becomes "pixelated".
2. Vector maps: The other type
of digital mapping is called vector
mapping. This is because it is made up of simple instructions
like a program. For example:
10. Join points 2 and 3 with a red line 2mm thick.
20. Join points 2 and 4 with a black line 0.5mm thick.
and so on.
Vextor mapping has the advantage
of being able to be searched for names, words and phrases.
In effect, it is its own database,
so is much more useful in a "find where" situation.
It is also scaleable, that is it remains in focus regardless
of scale.
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Using maps in GPS
Raster mapping:
This type of mapping is used by programs such as Trax, Fugawi or Oziexplorer,
for use on a computer or PDA. Raster mapping cannot be loaded into
any Garmin GPS, even the so-called map models.
You can however, load points and routes
from the maps, in to any Garmin GPS. You can do this manually,
or by computer
link, using Fugawi or Oziexplorer programs. Raster maps are
produced in Australia by Geoscience, and by Maptrax- this
page.
Vector
mapping:
GPS, whether hand-held, marine, or in-car, is used mainly to guide
you to a destination. Vector mapping is more effective in GPS, because
it is searchable for names and places. Vector mapping is also used
in GIS products.
All the cartography, marine and
land, supplied by Garmin, is in vector form for more effective "find" and
guide functions. Vector mapping is released by Garmin worldwide
under the Mapsource brand.
Other vector mapping is supplied by Geoscience
and Johnny Appleseed GPS.
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Johnny Appleseed GPS
