GRASS GIS manual: v.in.geoplot

NAME

v.in.geoplot - Creates vector points map from a Geoplot export file

KEYWORDS

SYNOPSIS

v.in.geoplot
v.in.geoplot help
v.in.geoplot [-q] input=string output=name [format=string] [delimiter=string] [creference=string] [xreference=float] [yreference=float] [xincrement=float] [yincrement=float] [length=float] [null=float] [--overwrite] [--verbose] [--quiet]

Flags:

-q: Quiet operation: no progress display
--overwrite: Allow output files to overwrite existing files
--verbose: Verbose module output
--quiet: Quiet module output

Parameters:

input=string: Geoplot ASCII export file
output=name: Vector map to store data points
format=string: Format of geoplot data file; Options: xyz,z; Default: xyz
delimiter=string: Data delimiter; Options: tab,space,comma; Default: tab
creference=string: Reference corner (top-left or bottom-left); Options: tl,bl; Default: bl
xreference=float: Easting of first data point; Default: 0.0
yreference=float: Northing of first data point; Default: 0.0
xincrement=float: Spacing between measurements
yincrement=float: Spacing between lines
length=float: number of measurements on one line
null=float: NULL data value to filter out

DESCRIPTION

v.in.geoplot

A module for easy import of Geoplot 3.0 ASCII data. Note that Geoplot data is in a local, non-geodetic reference system. Another tool such as v.transform will commonly be necessary to georeference and integrate it with existing data.

Geoplot is produced by and copyright of Geoscan Research.

BACKGROUND

This module provides a way to import Geoplot data at full resolution and precision into GRASS GIS in a straight-forward manner. It is assumed that the user has already fully post-processed the raw data, applying filters, normalizing value ranges etc. as needed in Geoplot. Data should then be exported from Geoplot as ASCII values so they can be read and converted to a vector map with this module.

The result of the import operation will be a new vector points map with each point representing exactly one record of the input file. Each record's nanotesla value will be stored in the double precision type field "nt" of the result map's attribute table. In addition, the original (local grid) coordinates of the record will be preserved as attribute fields "x" and "y".

USAGE

Geoplot is capable of producing a variety of different ASCII formats. The recommended way is to export "XYZ" files. However, lists of only Z values can also be imported, in which case the xincrement=, yincrement= and length= options have to be specified. All other export options, specifically the delimiter character, the NULL value representation and the "reference corner" are matched by equivalent options of v.in.geoplot. If no value is given fort null=, all records will be imported.

EXAMPLE

Given a Geoplot XYZ ASCII file named "readings.xyz" with the following structure:

0       0       1.374888
.125    0       1.074888
.25     0       .9748878
.375    0       .8748878
.5      0       .6748878
.625    0       .2748878
.75     0       .3748878
.875    0       .5748878
1       0       .8748878
[..]

The correct syntax is:

v.in.geoplot in=readings.xyz out=readings null=2047.5

This will create a new vector map "readings" with the import result.

AUTHOR

Benjamin Ducke, benjamin.ducke AT oadigital.net

Last changed: Mon Sep 28 2009

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