track2kml

#!/bin/bash
#
# track2kml - convert xplage track to KML animated path
#
#
# Copyright (c) 2007, 2008 Chris Kern
#
# This program may be distributed in accordance with the terms of Version 2 of the GNU General Public License
# published by the Free Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA,
# and is made available by the author without any warranty, including any implied warranty of merchantability
# or fitness for a particular purpose.
#
# Last edit: 02-Jun-08 by CK
#
#
# xplage(1) comma-separated value track data format
#
# Position	     1		   2		3	     4		  5	    6	     7
# Contents	<timestamp> , <longitude> , <latitude> , <altitude> , <heading> , <roll> , <pitch>
#
#


export LC_ALL=C								# POSIX locale forces dots as decimal points in $AWK

FEETPERMETER=3.2808399							# conversion divisor
SKIP=20									# default number of records to skip in animation interval
THRESH=50								# miles threshold for inferring geographical discontinuity
TRACKWIDTH=5								# width of displayed line path in Google Earth viewer

UMSG="usage: `basename $0` file.csv"

if [ -x /bin/nawk -o -x /usr/bin/nawk ]					# use nawk if available
then
	AWK=nawk
else
	AWK=awk
fi




function fragscan {							# scan adjacent track segments for discontinuities

	$AWK 'BEGIN	{
				FS = ","
		}
	
		NR == 1	{
				prevlon = $2; prevlat = $3; fragnum = 1
				name = substr(INFILE, 1, length(INFILE) - 4)
				printf("%s\n", name "-" fragnum ".csv")
	
				storeline()
		}
	
		NR > 1  {
				curlon = $2; curlat = $3
	
				if (geodist(prevlat, prevlon, curlat, curlon) > THRESH) {
					fragnum++
					printf("%s\n", name "-" fragnum ".csv")
				}
	
				storeline()
	
				prevlon = curlon; prevlat = curlat
		}	
	
		function geodist(lat1, lon1, lat2, lon2) {		# approximate geographical distance in statute miles
									# http://www.meridianworlddata.com/Distance-Calculation.asp
			x = 69.1 * (lat2 - lat1)
			y = 69.1 * (lon2 - lon1) * cos(lat1/57.3)
			return sqrt(x * x + y * y)
		}
	
		function storeline() {					# store current line in current fragment file
	
				file = name "-" fragnum ".csv"
				print $0 > file
		}
	
	
	     ' INFILE=${infile} THRESH=${THRESH} ${infile} # awk
}


function writepath {							# emit the KML code to display the path

	echo "<kml>"
	echo "  <Document>"
	echo "    <Style id=\"check-hide-children\">"
	echo "      <ListStyle>"
	echo "        <listItemType>checkHideChildren</listItemType>"
	echo "      </ListStyle>"
	echo "    </Style>"
	echo "    <styleUrl>#check-hide-children</styleUrl>"
	echo "    <Placemark>"
	echo "      <Style>"
	echo "        <LineStyle>"
	echo "          <color>ff0000ff</color>"
	echo "          <width>${TRACKWIDTH}</width>"
	echo "        </LineStyle>"
	echo "      </Style>"
	echo "      <LineString>"
	echo "        <altitudeMode>absolute</altitudeMode>"
	echo "        <coordinates>"
	
	$AWK 'BEGIN	{ FS = "," }
			{ printf("          %s,%s,%s\n", $2, $3, $4/FEETPERMETER) }
	     ' FEETPERMETER=${FEETPERMETER} ${fragfile} # awk
	
	echo "        </coordinates>"
	echo "      </LineString>"
	echo "    </Placemark>"
}


function writeanim {							# emit the KML code to animate the path

	echo "    <Style id=\"sn_icon56\">"
	echo "      <IconStyle>"
	echo "        <Icon>"
	echo "          <href>http://maps.google.com/mapfiles/kml/pal2/icon56.png</href>"
	echo "        </Icon>"
	echo "        <color>ff0000ff</color>"
	echo "      </IconStyle>"
	echo "    </Style>"
	
	$AWK 'BEGIN		{ FS = "," }
	
	      NR % skip == 0	{
					printf("    <Placemark>\n")
					printf("      <Style>\n")
					printf("        <IconStyle>\n")
					printf("          <heading>%s</heading>\n", $5)
					printf("        </IconStyle>\n")
					printf("      </Style>\n")
					printf("      <TimeStamp>\n")
					printf("        <when>%s</when>\n", $1)
					printf("      </TimeStamp>\n")
					printf("      <styleUrl>#sn_icon56</styleUrl>\n")
					printf("      <Point>\n")
					printf("        <altitudeMode>absolute</altitudeMode>\n")
					printf("        <coordinates>%s,%s,%s</coordinates>\n", $2, $3, $4/FEETPERMETER)
					printf("      </Point>\n")
					printf("    </Placemark>\n")
				}
	
	     ' FEETPERMETER=${FEETPERMETER} skip=${skip} ${fragfile} # awk
	
	echo "  </Document>"
	echo "</kml>"
}




# processing begins here

skip=$SKIP

while getopts s: arg
do
	case $arg in
		s)	skip=${OPTARG}
			shift
			;;
		\?)	echo "${UMSG}" 2>&1 && exit 1
	esac
done

if [ $# -ne 1 ]
then
	echo "${UMSG}" 2>&1 && exit 1

elif [ ! -r $1 ]
then
	echo "`basename $0`: input file $1 not found" 2>&1 && exit 1
fi

infile=$1
typeset -i count

for fragfile in $(fragscan)						# break track into geographic fragments, if necessary
do
	let count=count+1

	kmlfile="${infile%.csv}-${count}.kml"
	kmls="${kmls} ${kmlfile}"
	
	writepath >$kmlfile						# first pass: create the path
	writeanim >>$kmlfile						# second pass: add the animation

	rm $fragfile
done

if [ $count -gt 1 ]
then
	echo "`basename $0`: processed ${count} fragments: ${kmls}"
else
	mv $kmlfile "${infile%.csv}.kml"
fi