gdal trace raster outlines

gdal_outlines.sh

## run in a directory with many raster images containing nodata values that make their gdalinfo extents unreliable. output is a csv containing filename and data-containing extents, to be imported into postgis, sqlite, etc for running spatial queries. 
## usage: 

echo "file;GEOMETRY" > index.csv
declare -a FILES=$(ls -1 *tif);
for FILE in ${FILES[@]}; do
   FILE=${FILE%.tif}
   echo "$FILE.tif;" > $FILE.txt
   gdal_trace_outline $FILE.tif -ndv '0 0' -out-cs en  -wkt-out $FILE.wkt
   cat $FILE.wkt >> $FILE.txt
   cat $FILE.txt >> img_geoms.csv
   rm $FILE.wkt $FILE.txt
done
cat img_geoms.csv | perl -i -pe 's~;\n~;~smg' >> index.csv
rm img_geoms.csv