Geografic-Information-System/raster/r.in.ascii/r.in.ascii.html

<h2>DESCRIPTION</h2>

<em>r.in.ascii</em> allows a user to create a (binary) GRASS raster map
layer from an ASCII raster input file with (optional) TITLE.

<p>
The GRASS ASCII <b>input</b> file has a header section which describes
the location and size of the data, followed by the data itself.

<p>
The header has 6 lines: 

<div class="code"><pre>
north:   xxxxxx.xx
south:   xxxxxx.xx
east:    xxxxxx.xx
west:    xxxxxx.xx
rows:    r 
cols:    c 
</pre></div>

The north, south, east, and west field values entered 
are the coordinates of the edges of the geographic region. 
The rows and cols field values entered describe the dimensions 
of the matrix of data to follow. 
The data which follows is <em>r</em> rows of <em>c</em> integers. 

<p>
Optionally the following parameters can be defined in the header section:

<div class="code"><pre>
null: nn
type: float
multiplier: 2.
</pre></div>

<p>
"null" defines a string or number to be converted to NULL value (no
data).<br>
"type" defines the data type (int, float double) and is not required.<br>
"multiplier" is an optional parameter to multiply each cell value.

<h2>NOTES</h2>

The geographic coordinates north, south, east, and west
describe the outer edges of the geographic region.  They
run along the edges of the cells at the edge of the
geographic region and <em>not</em> through the center of the cells
at the edges.
The NW value occurs at the beginning of the first line of data, and the
SW value occurs at the beginning of the last line of data.

<p>
The data (which follows the header section) must contain
<tt>r</tt> <em>x</em> <tt>c</tt> values, but it is not necessary 
that all the data for a row be on one line. A row may be 
split over many lines. 

<p>
<em>r.in.ascii</em> may import <i>integer</i>, <i>floating point</i>, or <i>double</i> cell 
types using the <b>-i</b>, <b>-f</b>, and <b>-d</b> flags, respectively. 

<p>
The header information in ESRI Raster ASCII files differs from GRASS.  
To convert an Arc/Info (ArcView) ASCII grid file into GRASS, see 
<em><a href="r.in.gdal.html">r.in.gdal</a></em>.

<p>
SURFER (Golden Software) ASCII files may be imported by passing the <b>-s</b> flag.

<h2>EXAMPLE</h2>

The following is a sample <b>input</b> file to <em>r.in.ascii</em>: 

<div class="code"><pre>
north:                   4299000.00
south:                   4247000.00
east:                     528000.00
west:                     500000.00
rows:                         10   
cols:                         15   
null:                      -9999   

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
</pre></div>

<h2>SEE ALSO</h2>

<em>
<a href="r.import.html">r.import</a>,
<a href="r.out.ascii.html">r.out.ascii</a>,
<a href="r.in.gdal.html">r.in.gdal</a>, 
<a href="r.out.gdal.html">r.out.gdal</a>,
<a href="r.in.bin.html">r.in.bin</a>,
<a href="r3.in.ascii.html">r3.in.ascii</a>
</em>

<h2>AUTHOR</h2>

Michael Shapiro, U.S. Army Construction Engineering Research Laboratory<br>
Surfer support by Roger Miller

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