.TH prepros 1 "1 Oct 1993"
.SH NAME
prepros \- check contour input data for the nuages reconstruction package
.SH SYNOPSIS
.B prepros
.I \fIcnt_file_in\fR
[\|\fIcnt_file_out\fR\|] 
[\|\fB\-i \fIint_file_out\fR\|] 
[\|\fB\-n\fR\|] 
[\|\fB\-d\fR \fIvalue\fR\|] 
[\|\fB\-s\fR\|] 
[\|\fB\-S\fR \fIvalue\fR\|] 
[\|\fB\-pixel\fR\|]
[\|\fB\-approx\fR \fIvalue\fR\|]
[\|\fB\-x\fR \fIvalue\fR\|] 
[\|\fB\-y\fR \fIvalue\fR\|] 
[\|\fB\-c\fR \fIvalue\fR\|] 
[\|\fB\-m\fR \fIvalue\fR\|] 

.SH DESCRIPTION
.PP
The
.I prepros
preprocessor
looks for intersecting contour segments,
corrects contour orientation if necessary,
deletes incident vertices,
reports some statistics 
and, optionally,
approximates contours with a given error,
deletes co_linear or almost co_linear vertices,
perturbs identical vertices in adjacent cross-sections,
puts additional vertices on contour segments and
fills the contours with internal vertices.


.SH OPTIONS
.PP
.IP \fIcnt_file_in\fR 16
Contour input. Format:
.PP
.DT
.nf
                s 23          23 cross-sections
                v 17 z 0.2    17 vertices in first
                              cross-section, z=0.2
                {             begin first contour
                143.00 13.72  x,y of first vertex
                  .
                  .
                }             end first contour
                {             begin second contour
                  .
                  .
                }             end second contour
                v 24 z 8.3    24 vertices in second
                              cross-section, z=8.3
                  .
.fi
.PP


.IP \fIcnt_file_out\fR 16
output of processed data. Same format as \fIcnt_file_in\fR.

.IP "\fB\-pixel\fR" 
approximate contours with line segments.
Vertices are removed if its distance to the new line segment is 
smaller than a given error value. The procedure is highly recommended
for pixel-by-pixel contours.
 
.IP "\fB\-approx\fR \fIvalue\fR"
set the error value for
contour approximations to \fIvalue\fR. Default is 0.5.

.IP "\fB\-d\fR \fIvalue\fR"
delete segments with orientation difference smaller than \fIvalue\fR degrees.
Default is 1.0.

.IP \fB\-n\fR 
no suppression of co_linear vertices

.IP \fB\-s\fR 
perturb identical vertices in adjacent planes by a default value.
The default value is Min( smallest_cont_segment / 250.0, 4e-3) 

.IP "\fB\-S\fR \fIvalue\fR"
perturb identical vertices in adjacent planes by \fIvalue\fR.

.IP "\fB\-x\fR \fIvalue\fR"
put internal vertices at x\-distance \fIvalue\fR. Default is 10.0.

.IP "\fB\-y\fR \fIvalue\fR"
put internal vertices at y\-distance \fIvalue\fR. Default is 10.0.

.IP "\fB\-i \fIint_file_out\fR"
output of internal vertices. The inside of the contours is
filled with vertices on a regular grid. This may be useful to get
a regular tetrahedrization (see 
.I repros(1)
with option +int).

.IP "\fB\-c\fR \fIvalue\fR"
put additional vertices on contour segments at distance \fIvalue\fR.

.IP "\fB\-m\fR \fIvalue\fR"
Set the maxnumber of contours per plane to \fIvalue\fR. Default is 200.



.SH DIAGNOSTICS
Comments and exits with nonzero status for various trouble
conditions.

.SH SEE ALSO
repros(1), repros2visu(1), repros2tetra(1), nuages(1)
.SH AUTHOR
Bernhard Geiger
Copyright (C) 1993 by INRIA Sophia Antipolis

Permission to use, copy, modify, and distribute this
software and its documentation for educational, research,
and non-profit purposes without fee is hereby granted, provided that the
above copyright notice and the original authors name appear in all copies
and that both that copyright notice and this permission notice appear in
supporting documentation. This software is provided "as is" without express
or implied warranty.