[GRASS-user] Vector point from EXIF GPS data

[Joshua Arnott]

On 15/05/2011 6:31 pm, Juan Miguel Garijo wrote:
> Hello,
> This is my 'amateur' solution:
>
> def getXYfromFoto(foto):
>   proc=subprocess.Popen('exif -mt GPSLatitude '+foto, 
> shell=True,stdout=subprocess.PIPE)#foto: is the route to a jpg image 
> from a camera Sony  DSC-HX5V
>   stdout_value = proc.communicate()[0]
>   da=stdout_value[0:len(stdout_value)-1]
>   sp=da.split(', ')
>   
> lat=float(sp[0].replace(',','.'))+float(sp[1].replace(',','.'))/60+float(sp[2].replace(',','.')[0:5])/3600
>   print lat
>   proc2=subprocess.Popen('exif -mt GPSLongitude '+foto, 
> shell=True,stdout=subprocess.PIPE)
>   stdout_value = proc2.communicate()[0]
>   da2=stdout_value[0:len(stdout_value)-1]
>   sp2=da2.split(', ')
>   
> lon=float(sp2[0].replace(',','.'))+float(sp2[1].replace(',','.'))/60+float(sp2[2].replace(',','.')[0:5])/3600
>   print lon
>   proc3=subprocess.Popen('exif -mt GPSLongitudeRef '+foto, 
> shell=True,stdout=subprocess.PIPE)
>   stdout_value = proc3.communicate()[0]
>   da3=stdout_value[0:len(stdout_value)-1]
>   print da3
>   if da3[0:1]=='W':
>     lonLat='"-'+str(lon)+' '+str(lat)+'"'
>   else:
>     lonLat='"'+str(lon)+' '+str(lat)+'"'
>   print lonL #in wgs84
>   proc4=subprocess.Popen('echo '+lonLat+' | m.proj -i --quiet', 
> shell=True,stdout=subprocess.PIPE)#GRASS must be running, in my case 
> eur50 datum.
>   stdout_value = proc4.communicate()[0]
>   da4=stdout_value[0:len(stdout_value)-1]
>   print 'da4'
>   print da4
>   pse=da4.split(' ')
>   XY=pse[0].replace('\t',',')
>   print 'XY'
>   print XY
>   return XY# in UTM eu50 30N
>
> hope usefull for you
> Juan M. Garijo
Here is the solution I ended up with. It uses `jhead` rather than 
`exiftool` as for the 200 images I have to process I found it to be ~2x 
faster. It means jumping through some extra hoops with awk to get the 
lat/long formatting in a way m.proj will accept and some more to get the 
dates with / instead of :. The output is ready to pipe into GRASS using 
something like:

v.in.ascii in=exif.txt out=photos x=2 y=3 z=4 columns='filename 
varchar(40),x double precision,y double precision, z double precision, 
date varchar(19)'

#!/bin/bash

for FILENAME in "$@"; do
     # use jhead to read exif metadata
     EXIF=`jhead $FILENAME`

     # awk metadata into variables
     LON=`echo "$EXIF" | awk '/Longitude/ {sub(/m/,"'"'"'"); 
sub(/s/,"\""); print $4$5$6$3}'`
     LAT=`echo "$EXIF" | awk '/Latitude/ {sub(/m/,"'"'"'"); 
sub(/s/,"\""); print $5$6$7$4}'`
     ALT=`echo "$EXIF" | awk '/Altitude/ {sub(/m/,""); print $4}'`
     DATE=`echo "$EXIF" | awk '/Date\/Time/ {gsub(/\:/,"/");print $3}'`
     TIME=`echo "$EXIF" | awk '/Date\/Time/ {print $4}'`

     # transform to current projection
     if [ ${#ALT} -lt 1 ]; then ALT=0; XYZ=42; fi
     PROJ=`echo "$LON $LAT $ALT" | m.proj -i`
     PROJ_LON=`echo $PROJ | awk 'BEGIN {FS = "|"}{print $1}'`
     PROJ_LAT=`echo $PROJ | awk 'BEGIN {FS = "|"}{print $2}'`
     if [ ${XYZ:-0} -ne 42 ]; then PROJ_ALT=`echo $PROJ | awk 'BEGIN {FS 
= "|"}{print $3}'`; fi

     # output
     echo "$FILENAME|$PROJ_LON|$PROJ_LAT|$PROJ_ALT|$DATE $TIME"
done
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