136 lines
4.2 KiB
Groff
136 lines
4.2 KiB
Groff
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.\" Copyright (C) 2017 Alessandro Menti
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.\"
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.\" This program is free software; you can redistribute it and/or
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.\" modify it under the terms of the GNU General Public License
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.\" as published by the Free Software Foundation; either version 2
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.\" of the License, or (at your option) any later version.
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.\"
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.\" This program is distributed in the hope that it will be useful,
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.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
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.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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.\" GNU General Public License for more details.
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.\"
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.\" You should have received a copy of the GNU General Public License
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.\" along with this program; if not, write to the Free Software
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.\" Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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.\" Or try here: http://www.fsf.org/copyleft/gpl.html
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.\"
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.TH FGELEV 1 2020-11-15 FlightGear "FlightGear man pages"
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.SH NAME
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fgelev \- Compute FlightGear scenery elevation for a given list of points
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.SH SYNOPSIS
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\fBfgelev\fR [\fB\-\-expire\fR \fInum\fR] [\fB\-\-print\-solidness\fR]
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[\fB\-\-fg\-root\fR \fIrootdir\fR] [\fB\-\-fg\-scenery\fR \fIscenerydir\fR]
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[--tile-file osgbfilename] [--use-vpb]
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.SH DESCRIPTION
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.B fgelev
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is a standalone utility that, given a list of points on standard input, prints
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the corresponding elevation for each of them on standard output. It can also
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(optionally) print whether the material covering that point is solid or not.
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The list of points must be in the following form:
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\fIid lon lat\fR
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where \fIid\fR is an arbitrary identifier for the point, \fIlon\fR is the
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longitude of the point and \fIlat\fR is the latitude of the point. Positive
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longitudes (latitudes) correspond to points located in the Eastern (Northern)
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hemisphere; negative ones correspond to points located in the Western
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(Southern) hemisphere.
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The list of elevations returned by
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.B fgelev
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is in the following form:
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\fIid: elev solid\fR
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where \fIid\fR is the identifier of the point passed as input, \fIelev\fR is
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the elevation of the point in meters (or \fB-1000\fR if the elevation of the
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given point was not found) and \fIsolid\fR is:
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.IP \(bu 3
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the string
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.B solid
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if the parameter
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.B \-\-print\-solidness
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was passed to
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.B fgelev
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and the material covering the point is solid;
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.IP \(bu 3
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the string
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.B \-
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if the parameter
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.B \-\-print\-solidness
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was passed to
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.B fgelev
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and the material covering the point is not solid;
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.IP \(bu 3
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absent if the parameter
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.B \-\-print\-solidness
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was not passed to \fBfgelev\fR.
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.SH OPTIONS
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.TP
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\fB\-\-expire\fR \fInum\fR
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To speed up elevation data retrieval,
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.B fgelev
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uses an internal cache. This option lets the user specify the number of
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requests after which, if a point was not queried in them, it should be marked
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as expired. By default,
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.B fgelev
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expires points not queried in the last \fB10\fR requests.
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.TP
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\fB\-\-print\-solidness\fR
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Require
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.B fgelev
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to print the solidness of the material covering the queried point. See the
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.B DESCRIPTION
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section for more details.
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.TP
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\fB\-\-fg\-root\fR \fIrootdir\fR
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Set the FlightGear data root directory (\fB$FG_ROOT\fR) to \fIrootdir\fR. If
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this option is not set,
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.B fgelev
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uses the path specified in the
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.B FG_ROOT
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environment variable or, absent that, the FlightGear data directory chosen at
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the time the program was compiled.
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.TP
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\fB\-\-fg\-scenery\fR \fIscenerydir\fR
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Set the FlightGear scenery directory (\fB$FG_SCENERY\fR) to \fIscenerydir\fR.
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If this option is not set,
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.B fgelev
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uses the path specified in the
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.B FG_SCENERY
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environment variable or, absent that, the
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.B Scenery
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subdirectory inside \fB$FG_ROOT\fR.
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.TP
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\fB\-\-tile\-file\fR \fIosgbfilename\fR
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Use a specific tile file when searching for elevation details, instead
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of scanning through the whole world.
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.TP
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\fB\-\-use\-vpb\fR
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If specified, enables WS3.0 scenery behaviour, searching under the vpb/
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subdirectory.
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.SH "EXIT STATUS"
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.B fgelev
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exits with
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.B EXIT_SUCCESS
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on success, with
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.B EXIT_FAILURE
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if it is unable to read data from standard input or to load the scenery.
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.SH ENVIRONMENT
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.IP "\fBFG_ROOT\fR" 4
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If
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.B FG_ROOT
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is set and
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.B \-\-fg\-root
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is not set, it specifies the root data directory to use.
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.IP "\fBFG_SCENERY\fR" 4
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If
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.B FG_SCENERY
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is set and
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.B \-\-fg\-scenery
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is not set, it specifies the scenery directory to use.
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.SH "SEE ALSO"
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.BR fgfs (1)
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