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To learn about basic sites (point data) commands you will need to load
a sites file containing the locations of landmark sites in the city of
Harrisonburg.
To convert the ArcView shape data file of landmark sites in Harrisonburg
into a GRASS sites file:
- Type s.in.shape
input=ltp51660.shp
- input=name:
the name of the ArcView shape file with sites data
To load the sites map of the landmarks into the monitor:
- Type d.sites
map=ltp51660
- map=name:
the name of the sites map to open
The sites map should now be visible in the monitor and will look similar
to Figure 5.1 below.
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Figure 5.1: Landmark sites
map in a monitor
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Displaying the scale
The scale for this sites map can be plotted over the sites map. To draw
the scale:
- Type d.scale
bcolor=black
tcolor=white at=0,0
- bcolor=name:
background color underlying the scale and north arrow
- options: white,
red,
orange,
yellow,
green,
blue,
indigo,
violet,
magenta,
brown,
gray, and black
- tcolor=name:
foreground color in which the text, scale, and north arrow are drawn
- options: white,
red,
orange,
yellow,
green,
blue,
indigo,
violet,
magenta,
brown,
gray, and black
- at=x,y
:geographic coordinates designating the location at which the upper
left corner of the scale is to be placed
The sites map will now have a black and white scale on it in the monitor
and will look similar to Figure 5.2 below.
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Figure 5.2: Landmark sites
map with scale
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Finding the coordinates of a point
The coordinates of a particular point in a sites map can be printed to
the command line interface. To print the location of a point:
- Type d.where
-1
- -1:
print the location of only the first point clicked on the map
The command line interface will prompt you to use the mouse to click
on the location of the site you want to locate. This prompt will look
similar to Figure 5.3 below.
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Figure 5.3: Where point prompt
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- Place the mouse pointer over the site on the map you want to identify,
and click the left mouse button.
The location of the site will be printed to the command line interface.
This location will look similar to Figure 5.4 below (your screen may look
different depending on what location you clicked on).
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Figure 5.4: Where point information
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Creating a buffered map
A new sites map can be created that is a buffered version of the original
sites map. To create a buffered sites map of the landmark sites:
- Type s.buffer
input=ltp51660
output=landmarks_buffer radius=40
- input=name:
the name of the original sites map
- output=name:
the name of the new buffered sites map
- radius=value:
the radius (in pixels) over which to create the buffer around each
site
To view the buffered sites map use d.erase
to remove the old map and d.sites
to open landmarks_buffer.
The buffered map should now be visible in the monitor and will look similar
to Figure 5.5 below.
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Figure 5.5: Buffered landmarks
sites map in a monitor
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Converting sites map to a raster or vector map
A sites map can be converted into a new raster or vector map. To convert
the sites map of landmarks to raster and vector maps:
- Type s.to.rast
input=ltp51660 output=landmarks_raster
- Type s.to.vect
input=ltp51660 output=landmarks_vector
- input=name:
the name of the original sites map
- output=name:
the name of the new raster or vector map
IMPORTANT: The created raster map can be
viewed using the raster display command. The created vector map can be
viewed using the vector display command.
Click the Next
button to finish the tutorial.
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