.TH Gline 2G G-language
.SH NAME
Gline \- Create a new vector (digit) file by
extracting linear features from a thinned cell-file.
.br
.I "(G Language Tool)"
.SH SYNOPSIS
.B Gline
.I "cell-file digit-file [option\*=\fIvalue\fR] [option\*=\fIvalue\fR]"
.SH DESCRIPTION
.I Gline
scans the named \fIcell-file\fR and extracts thinned linear features into a vector (digit) file.
Options are:
.TP 
.RI format\*= format
Format of the digit file, either binary or ascii.  
Default is binary vector (digit) files. 
.br
.ns
.TP 
.RI attrib\*= attribute_type 
Attribute type of the extracted vectors, either linear or area_edge.
Specifying linear will cause extracted vectors to have linear attributes.
Specifying area_edge will cause extracted vectors to have 
area_edge attributes.  Default is linear attributes. 
.br
.PP
.I Gline 
assumes 
that the input cell-file has been thinned using 
.I Gthin.    

.SH NOTES
.I Gline
extracts vectors from a cell file that represent linear features 
or arcs in digit terminology (i.e. roads, streams,
political boundaries).  These arcs may denote linear attributes 
(roads or streams), or may denote an area edge attribute (political 
boundary).  The attribute type option allows you to set linear or
area edge attributes for all of the extracted vectors.

The 
.I GRASS Tool Gpoly
may be used to extracts vectors from a cell file that represent area features
(i.e. classes of soil, ranges of elevation). 

You will need to run 
.I support.vect
on the resultant vector (digit) files to build the dig_plus information. 

.I Gthin  
and
.I Gline
may create excessive nodes at every junction, and
small spurs or "dangling lines" during the thinning and 
vectorization process.
These excessive nodes and spurs may be removed by  
.I Gtrim.

.SH BUGS
The input cell-file MUST be thinned by
\fIGthin\fR
, if not 
\fIGline\fR
may crash.

.SH "SEE ALSO"
\fIGthin[1]\fR, \fIGtrim[1]\fR, \fIGpoly[1]\fR, \fIsupport.vect[1]\fR

.SH "AUTHOR"
.nf
Mike Baba
DBA Systems, Inc.
10560 Arrowhead Drive
Fairfax, Virginia 22030

