.TH v.in.dlg
.SH NAME
\fIv.in.dlg\fR \- Converts an ASCII USGS DLG-3 Optional file
to a binary GRASS vector (dig) file.
.br
.I (GRASS Vector Data Import Program)
.SH SYNOPSIS
\fBv.in.dlg\fR
.br
\fBv.in.dlg help\fR
.br
\fBv.in.dlg\fR [\fB-l\fR] \fBinput\*=\fIname \fBoutput\*=\fIname\fR [\fBmatt\*=\fIname\fR] [\fBbase\*=\fIval\fR]
.SH DESCRIPTION
This program converts an ASCII USGS DLG-3
(\fIdlg\fR) file
into a binary GRASS vector (\fIdig\fR) file.  
.br
\fBWarning\fR:  The program reads DLG-3 Optional
format only. 

\fIv.in.dlg\fR also creates a \fIdig_att\fR file containing the label
information 'stripped' from the DLG-3 file (the first minor attribute
for each record unless \fImatt\fR is specified).

If the \fImatt\fR is specified, \fIv.in.dlg\fR creates an additional
attribute file containing identifiers for every record with correspon
ding
multiple attributes.  In this case \fImatt\fR file contains identifiers
starting with base \fIbase\fR for the attributes stored in \fImatt\fR
file (as opposed to the first minor attributes with no \fImatt\fR file).                             
The example of \fImatt\fR with \fIbase\fR = 34 would be:

.br
	34	0	0
.br
	35	180	201
.br
	36	180	208
.br
		170	240
.br
		190	201
.br
	37	160	220
.br

With the corresponding \fIdig_att\fR looking like this:
.br

	A 648467.190000 4456367.320000     34
.br
	L 667989.290000 4458393.520000     35
.br
	L 651002.470000 4473793.390000     36
.br
	L 663816.680000 4471412.080000     37
.br


However, the user must run \fIv.support\fR (or \fIv.import\fR option 4)
on the \fIoutput\fR file created by \fIv.in.dlg\fR to create a
\fIdig_plus\fR file containing the file topology, before using the
\fIoutput\fR file in \fIv.digit\fR.

The user can avoid this two-step process by converting
the ASCII DLG-3 file to binary GRASS vector format
using option 1 of the GRASS program \fIv.import\fR.

.LP
.IP \fB\-l\fR 18
Give precedence to line information (default is area).

.LP
\fBParameters:\fR
.IP \fBinput\*=\fIname\fR 18
Name of USGS DLG-3 Optional format input file.
.IP \fBoutput\*=\fIname\fR 18
Name to be assigned to the binary GRASS vector files created.
.IP \fBmatt\*=\fIname\fR 18
Name of file with multiple attributes (optional). 
.IP \fBbase\*=\fIval\fR 18
Identifier base for multiple attributes (default is 1). 
.LP
If the user simply types \fBv.in.dlg\fR without specifying parameter
values on the command line, the program will prompt the user to enter these.
.SH NOTES
\fBArea vs Line Precedence: \fR
.LP
Some machine-processed DLG-3 files do not make the distinction between
line edges and area edges.  For example, in a roads map, where
the desired information is line edge data, 
a downtown block surrounded by roads may be processed as an area.
Because of this, the user is asked to
choose whether to give precedence to areas or lines.  If precedence is
given to lines, the user should be aware that any lines that bound 
unlabeled areas in the DLG-3 file will
be stored as line data.  Any unlabeled areas would therefore be lost (this is
only a concern when areas are unlabeled;  labeled area information will be
retained).  If precedence is given to areas, lines will be stored as boundaries 
to areas that are unlabeled.


\fBBuilding support files with \fIv.support\fR: \fR
.LP
When you run \fIv.support\fR you will have the option of snapping the nodes
in your vector file that fall within a certain threshold of one another.
WARNING:  the default threshold is calculated using the scale of the
original DLG-3 file.  If the threshold is too high, excessive snapping may 
occur, destroying the file!!  With \fIv.support\fR, the user has the option
of snapping or not snapping nodes, and further, of setting a particular snapping
threshold.
.SH SEE ALSO
.I v.digit,
.I v.import,
.I v.support
.SH AUTHOR
Dave Gerdes, U.S. Army Construction Engineering Research Laboratory
.br
Irina Kosinovsky, U.S. Army Construction Engeneering Research Laboratory