maxxc - maximise cross country flights
Copyright (C) 2008  Tom Payne



INTRODUCTION

maxxc is a program to maximise cross country flights.  Given an IGC file, it
finds the largest open distance (via up to three turnpoints), out-and-return
and triangular flights according to various cross country league rules.

The output is in GPX format and a program is provided to convert this into KML
format for viewing in Google Earth.

This software is designed to be used on XC league servers, it is not designed
for end users.



QUICK START

Type "make" to build the software and "make install" (as root) to install it.

To run the software use:
	maxxc -l league IGC-FILENAME.igc
The only required parameter is -l to set the XC league.  The currently
supported leagues are:
	frcfd	Coupe Fédérale de Distance (France)
	uknxcl	National Cross Country League (UK)
	ukxcl	Cross Country League (UK)
maxxc will read the IGC file, calculate the largest flights and write a GPX
file to the standard output.  You can send the output to a file using either
the -o option or redirection.



VISUALISING IN GOOGLE EARTH

The program maxxc-gpx2kml reads a GPX file produced by maxxc from the standard
input and produces a nice Google Earth KML file as output.  You probably want
to specify the -t option to maxxc to include the tracklog in the GPX file,
otherwise you'll just see the optimised flights.

For example:
	maxxc -l frcfd -t IGC-FILENAME.igc | maxxc-gpx2kml > KML-FILENAME.kml

maxxc-gpx2kml requires Ruby (http://www.ruby-lang.org/).



ALGORITHM NOTES

The algorithm is basically the same as optigc:
	http://freenet-homepage.de/streckenflug/optigc.html
Some speed-ups have been added, and the algorithm has been adapted to
different league rules.

The algorithm is deterministic and should always find the largest flight.
Please inform the author if you find any counter-examples.

In some cases the optimisation can take a VERY long time!  A particularly
difficult class to optimise is CFD flat triangles when the tracklog is
basically an out-and-return.  Flat triangles have very few constraints and so
maxxc has to consider thousands of nearly identical flat triangles, which
takes a long time.

I haven't yet written a detailed description of the algorithm, sorry!



COMPARISONS WITH OTHER FLIGHT OPTIMISATION SOFTWARE

maxxc should always find the longest flight.

Both CompeGPS (http://www.compegps.com/) and parawing.net
(http://carnet.parawing.net/form_conv_public.php) seem to use a geometric
algorithm or heuristics which are fast and wrong.

XContest (http://www.xcontest.org/) seem to have an algorithm that is both
correct and very fast.  maxxc has room for improvement!



AUTHOR

Tom Payne <twpayne@gmail.com>
Based on an algorithm developed by Thomas Kuhlmann.



LICENSE

This program is free software: you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation, either version 3 of the License, or (at your option) any later
version.

This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
details.

You should have received a copy of the GNU General Public License along with
this program.  If not, see <http://www.gnu.org/licenses/>.

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