Geografic-Information-System/display/d.measure/d.measure.html

<h2>DESCRIPTION</h2>

<em>d.measure</em> provides the user with an interactive
way to measure the lengths and areas of lines and polygons
drawn by the user in the active frame on the graphics
monitor.  Lines and polygons are drawn using a pointing
device (mouse).  Each line segment is drawn in colors
<b>c1</b> and <b>c2</b>.  A mouse button menu indicates
that the user can find out the geographic coordinates of
the cursor location, draw line segments between
user-specified vertices, and quit <em>d.measure</em>. Lines
and polygons are defined by the series of vertices marked
by the user. If more than two successive vertices are
drawn, <em>d.measure</em> prints the area encompassed
(<em>d.measure</em> will assume the area is closed even if
the user has not joined the first and last vertices).
<!-- (not [currently] true!)  Line lengths are stated in the same units
as those of the current LOCATION. In a XY-LOCATION, where no units are
available, <em>d.measure</em> prints a warning and gives results without
units. -->
Areas can be stated in hectares, square miles, square meters and
square kilometers.

Lines and polygons drawn using <em>d.measure</em> will
overlay (not overwrite) whatever display currently appears
in the active frame on the graphics monitor.  The user can,
for example, run 
<em><a href="d.rast.html">d.rast</a></em> or 
<em><a href="d.vect.html">d.vect</a></em> prior to running
<em>d.measure</em>, and use raster and/or vector maps as a backdrop.

<h2>NOTES</h2>

<em>d.measure</em> uses all segments drawn by the user when computing area. 
If the user draws an area within another area, the combined 
area of both regions will be output. 

<h2>TODO</h2>

Output lengths in the same units as those of the current LOCATION as
found in the <tt>PROJ_UNITS</tt> file (see <em>g.proj</em>).
Volunteers are welcome for this task.

<h2>SEE ALSO</h2>

<em><a href="d.frame.html">d.frame</a></em><br>
<em><a href="d.graph.html">d.graph</a></em><br>
<em><a href="d.rast.html">d.rast</a></em><br>
<em><a href="d.vect.html">d.vect</a></em><br>
<em><a href="d.where.html">d.where</a></em><br>
<em><a href="g.proj.html">g.proj</a></em>


<h2>AUTHORS</h2>

James Westervelt, 
<br>
Michael Shapiro, <br>
U.S. Army Construction Engineering 
Research Laboratory

<p><i>Last changed: $Date$</i>