Incorporating Google Maps and Google Earth into your Remote Sensing Applications J. Freemantle OARS Technical Meeting, Dec 11, 2006
Outline Overview of Google Earth Simple examples using keyhole markup language (kml) Using the Google Maps/Earth API Some community examples Questions?
Google Earth Client/Server Application Free for basic version Works on Windows (2000/XP), Mac OS , Linux
Google Earth Overview Satellite and Airborne Imagery 1-3 years old Spatial resolution in countryside < 15 m. Major US cities less than 1-2 feet (20-40 cm). Parts of Manhattan (Fulton Co.) 10 cm!
York University
Newmarket
Low vs high res. data (Aurora)
Toronto
New York City (20 cm)
New York City (10 cm)
10 and 20 cm images compared
Primary Data (roads etc)
Boundary Errors
Why Google? Its free!!! Generally up to date Large user community Developer/programmer friendly Easy to learn Platform independent Its cool!
Assumptions/Caveats Check the fine print of End User License (EUL) for your situation. Google Earth 4.0 (Beta), free version. Public/Private data? (choose wisely).
Simple Examples using KML Point Pictures Tracks Overlays Links to external data
Warning Code Examples!
Keyhole Markup Language (kml) Xml grammar and file format for describing geographic features in google earth/maps Points Lines Polygons Models links
Keyhole Markup Language (KML) KML files can be shared. KMZ files are a compressed version of KML files. Google Earth processes kml files like web browsers process html files.
Kml example: Simple point OARS Meeting Presented by Jim Freemantle Dec 11, :00 pm Room 129 Chemistry Building, York University, Toronto. ]]> , ,0
Simple Point
Simple point, with link OARS Meeting details ]]> , ,0
Simple point with link
Simple point, with image OARS Meeting details ]]> , ,0
Simple point with image
Track t0490f13 t0490f13 ]]> , , , , , , , , ,
Track
GeoTagging
Requirements GPS device Camera with EXIF format jpg files and internal clock Software to sync gps track with time of photo Software to create google earth file (.kml)
GeoTagging GPS Devices Used Sony GPS-SC1 ($129.00) Garmin Forerunner 201 Runners GPS ($159.00)
GeoTagging Software Used GPSBabel (NMEA to GPX) GPS Image Tracker (Sony) (Not required) iTag
GeoTagging
Overlays Getting your georeferenced data into Google Earth Need georeferenced data Manually imported, as a jpg image, and matched to Google Earth
Overlays
Links Images External websites via url Databases
Track with link t0489f06 t0489f06 Link to Flight Log ]]> , , , , , , , , ,
Track with link
Point with link Waskesiu <![CDATA[Aeronet Sites Worldwide <a href=" type_one_station_opera_v2_new?site=Waskesiu&nachal=2&aero_water=0&level=1 &if_day=0&year_or_month=0">Link to Waskesiu data ]]> , ,550
Point with Link
Google Earth/Map Application Programmer Interface (API) Sign up for your key Can be used only on requested web accessible directory eg. Receive example script and put it in that directory Build Google Map applications from there
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" " Jim's Google Maps JavaScript API Example from M. Brown <script src=" type="text/javascript"> //<![CDATA[ var largemapcontrol = new GLargeMapControl(); function load() { if (GBrowserIsCompatible()) { var map = new GMap(document.getElementById("map")); GEvent.addListener(map,'click',function(overlay,point) { var latLngStr = '(' + point.x + ', '+ point.y + ') '; var message = document.getElementById("message"); message.innerHTML = latLngStr; }); map.centerAndZoom(new GPoint( , ), 4); map.addControl(largemapcontrol); } //]]>
Google Map API
Google Earth API Link to dynamically generated kml No API key required See ml#tracking_point
Google Earth Example <?php // get the time $timesnap = date("H:i:s"); $BOX=$_GET[BBOX]; // split the client's BBOX return by commas and spaces to obtain an array of coordinates $coords = preg_split('/,|\s/', $BOX); // for clarity, place each coordinate into a clearly marked bottom_left or top_right variable $bl_lon = $coords[0]; $bl_lat = $coords[1]; $tr_lon = $coords[2]; $tr_lat = $coords[3]; // calculate the approx center of the view -- note that this is innaccurate if the user is not looking straight down $userlon = (($coords[2] - $coords[0])/2) + $coords[0]; $userlat = (($coords[3] - $coords[1])/2) + $coords[1]; $response = ' '; $response.= ' '; $response.= ' '.$timesnap.' '; $response.= ' '; $response.= " $userlon,$userlat,0 "; $response.= ' '; echo $response; ?>
Examples from the Community Mashups
Acknowledgements Data providers J. Miller (York U), A. Smith (Agr. Canada) Colleagues I. Lumb, L. Gray
Resources Hacking Google Maps and Google Earth by Martin C. Brown Check back on the OARS website for a copy of these slides and list url of useful links
Resources Interesting links GeoTagging "adding location information to pictures" Interesting discussion at Canadian Canoe Routes on this topic: Mashups:
Questions?