How to merge many individual KML layers into one?

Question

I'd like to open a USGS KML file of bedrock geology for an entire county, but there are over 2,000 individual polygon layers. Does anyone know if there is a way to merge all of these layers together into one file before opening in QGIS?

Answer 1

Here a simple shell script ("ogr_kml_merge.sh") which uses ogr2ogr:

#!/bin/sh

# Markus Neteler, 2008
# merge KML files

PROG=`basename $0`

if [ $# -lt 1 ] ; then
 echo "Merges KML files together (mosaik)"
 echo "Usage:"
 echo "  $PROG *.kml"
 echo "  $PROG a.kml b.kml c.kml"
 echo "At then end of the merge you can select a new name"
 exit 1
fi

LIST="$@"
OUT=file_merged

rm -f $OUT.kml

ogr2ogr -f KML $OUT.kml $1
shift

for i in `seq 1 $#` ; do
  echo "Appending #$i: $1"
  ogr2ogr -f KML -update -append $OUT.kml $1 -nln $OUT `basename $1 .kml`
  shift
done

echo "Written: $OUT.kml"

echo -n "Enter file name for new KML (or CTRL-C): "
read NEW
NEW=`basename $NEW .kml`
mv $OUT.kml $NEW.kml

echo "Written as: $NEW.kml"

Hope this gives the idea.

Answer 2

One option would be to write a "wrapper" KML file and include links to each file in the wrapper, using the KML NetworkLink. Although it says "network", the Link element can contain a local file path instead. You can also use this in a KMZ structure

Answer 3

Create a folder in which you'll then add the individual kml/kmz files. Go to Save as and in your destination, save this folder as a kml.Your result will be a single kml file. Hope this helps

Answer 4

With the plug in MMQGIS is possible to merge to many .kml files into one only shape file once you have uploaded all of you .kml files in Q-GIS.

To install the MMQGIS, simply you have to go to the plugin bottom, and select in manage sources and plugin.

Once the plugin is installed, go to combine, and after merge layers. Done!

Answer 5

I assume that the issue is not that there are multiple files, but there is a single KML/KMZ with lots of folders that is loading as individual layers, which is generally unsuitable for manipulation and performance. You can see why this would be a problem:

Given that you asked how to merge all these layers together before opening in QGIS, there are two approaches:

Quick solution: Use KML Merger, an online tool located at https://kmlmerger.com/. Do note that you'll have to feed it two KML files, so you might need to create a KML with no data present, or create a dummy KML with one element of your original data set, then delete that element in the exported file. This can easily be done with a text editor.

Automated solution: Try this Python script to flatten XML files. It does read the KML line by line as if it were text, so it may not work on some valid KML files.

"""kmlflatten.py: reads a KML file as text, and strips out all Folder tags except the first and last.  usage: python kmlflatten.py IN [OUT]"""

import os
import sys

if len(sys.argv) >= 2:
    kmlfilein = sys.argv[1]
    if len(sys.argv) >= 3:
        kmlfileout = sys.argv[2]
    else:
        dotext = kmlfilein[kmlfilein.rfind(os.extsep):]
        fname, ext = os.splitext(kmlfilein)
        kmlfileout = fname + '_flattened' + ext
else:
    kmlfilein = 'doc.kml'
    kmlfileout = 'doc_flattened.kml'


with open(kmlfilein, 'r') as fi:
    with open(kmlfileout, 'w') as fo:
        folder, skip = False, False
        for line in fi.readlines():
            stline = line.strip() #remove indents, but hang onto original line.
            if not folder: #copy up to first <Folder> tag
                if stline == '<Folder>':
                    folder, skip = True, True
                    fo.write(line) # write the first folder!
                else:
                    fo.write(line)
            if folder: #copy lines except for the <Folder> tags and the <name> tag immediately proceeding
                if skip:
                    skip = False
                elif stline == '</Document>':
                    fo.write('\t</Folder>\n</Document>\n') # make sure to write the last </Folder> before done
                elif stline == '<Folder>':
                    skip = True
                elif stline == '</Folder>':
                    pass
                else:
                    fo.write(line)

A more suitable solution would be to use an XML parsing library to move all Placemark nodes into the first Folder, and perhaps first save any data about the Folder (like order or name) into the Placemark feature itself before it's destroyed.