Hi Google fans, mashup hackers, GPS geeks, geotaggers lovers, or anyone who has time on hand.
Here’s my simple howto for mashing up google maps, geotagged photos on picasa web albums, and gps tracks.
note: below is a screenshot. scroll to the bottom of this post for the interactive map

motivation: As mentioned in my previous post, syncing GPS tracks is a very convenient way for geotagging photos. Our friendly giant, Google already has some fantastic services for photos, geotagging, maps but apparently we do not see support for GPS tracks.
summary: This online mashup requires mainly a web browser with a little manual work.
steps:
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1. Upload geotagged photos to Picasa web albums & download KML (google earth) format
2. Convert gps tracks to KML format
3. Merge GPS tracks and Photos KML
4. Upload merged KML to google pages
5. Request google maps to open KML
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pre-requisites:
You must have a google account. This is for uploading to picasa web albums and google pages.
You also know how to geotag photos by syncing GPS tracks. This has been mentioned briefly in my previous post.
Step 1.
After geotags have been saved to the photos EXIF, you see a little compass icon on photos in picasa web albums. Select the photos you want and upload them to a web album. After uploading, go to the web albums and click “View Map”. Save the “View in Google Earth” link which is a KML format.
Step 2.
Convert your GPS tracks (GPX, NMEA etc) to KML format. You could use the free powerful GPSBabel or convert it online at GPS Visualizer.
Step 3.
Open your favorite notepad/text/xml editor/ide and copy the kml data into the photos kml If you find it tricky merging the KML files by hand, try using this utility called KML Merge
Hint: If you would like to edit a little KML, you could customise what to display and perhap place tracks information (speeds, time, altitudes) in the little bubbles when clicked on.
Step 4.
We have to store the GPS tracks somewhere anyway, so the free and good way is to upload to googlepages. Under the right section there’s box call uploaded stuff. Click upload files, and select the KML file to be uploaded. Copy the url of the upload file.
Step 5.
Visit Google Maps. In the search box, paste the url where your KML is hosted. Tata, you get GPS tracks, geotagged photos on the interactive map! Click on share this map to email or embed this mashup on your blogs.
the trick: if you haven’t notice, this mashup is built mainly on the fact google maps is able to layer the google earth format (KML) onto google maps online.
To send a linked url map to your friends, append a url encoded kml url to google maps.
eg: http://maps.google.com/maps?q=http%3A//joshuakoo.googlepages.com/HendersonPicasaPhotos.kml
Here’s the result:
View Larger Map
conclusion: this is a really simple, rough mashup for google maps, photos, gps tracks but it shows some possibilities of what it can be done. i would also like to point out that everytrail has a fantastic services for gps tracks which supports google maps, and photos geotagging. Unfortunately, its photos uploading is pretty rudimentary but one would still use if everytrail if there’s no preferences for picasa web albums.
