Download global data including landcover, elevation, and population data that covers the entire planet.
Create and save map overlays (KML ground overlay format). Export to your computer with iTunes File Sharing.
Using downloaded elevation data you can generate a 3D anaglyphic stereo view of standard, satellite, hybrid, and terrain maps.
Use the same data to see possible future sea-level changes caused by global warming.
You can also display standard KML/KMZ files containing point, line, and polygon features, as well as your own images and maps (KML ground overlay lat/lon box format).
How to Use
The app contains two menu bars (top and bottom), a slider, and an information field at the bottom.
Top Menu Bar
There are six bottons:
Search - Type the name of a city or town, or enter a latitude and longitude (comma seperator).
Load - Load a previously saved data layer (actually a KML file), or one of your own. Works only when device is in portrait mode.
Save - Stores the current layer to a file. The file name is the current date and time (yyyyMMdd_hhmmss).
Trash - Remove a file from the documents directory on the device. Works only when device is in portrait mode.
Add data - Tap this to reveal a secondary menu bar. This menu bar lets you download geo-data over the current map area
(an area slightly larger than the screen size) from our webserver. Saved data is stored in the documents directory and can be downloaded to your computer using iTunes file sharing.
Land - Global AVHRR Landcover created by Univ. Maryland, Dept. Geography (30 arc-second per grid cell, 13 distinct landclasses). Landcover classes are
Water, Evergreen Needleleaf Forest, Evergreen Broadleaf Forest, Deciduous Needleleaf Forest, Deciduous Broadleaf Forest,
Mixed Forest, Woodland, Wooded Grassland, Closed Shrubland, Open Shrubland, Grassland, Cropland, Bare Ground, Urban and Built Up.
DEM - GLOBE Elevation provided by NOAA (meters above sea-level, 30 arc-second per grid cell). Elevation data is displayed as a false color image.
To obtain the actual elevation value (in meters),
convert the red-green-blue value to hue-saturation-brightness. The elevation is hue*8848/359.
Pop - Gridded Population produced by SEDAC/Columbia Univ. (persons per sq. km, 2.5 arc-minute per grid cell). Population data is displayed as a false color image.
To obtain the actual population density (in persons per sq. km), convert the red-green-blue value to hue-saturation-brightness.
The population density is exp(hue*log(29650)/359).
Sea - Possible future sea-level changes caused by global warming. Sea-Level changes are encoded as follows: green
(4.8 meter rise caused by West Antarctic ice sheet), yellow (7.2 meter rise caused by Greenland ice sheet), and red (12 meter combined rise).
Info - Tap this to get to this document. Tap again to dismiss.
Bottom Menu Bar
There are five bottons:
1-4 - This changes the current map layer.
Show/Hide - Turns on/off the current map layer.
Clear - Erases the contents of the current map layer.
Map/Sat/Ter/Hyb - Choose one of 4 background maps.
GPS/Off - When off, blue cross-hairs appear. Scroll (1 finger) and zoom (2 finger pinch). When the GPS is selected, the center of the map is automatically set to the current GPS location.
The slider controls the transparency of the current map layer.
The information field (lower right) displays the latitude and longitude at the center of the screen. If data has been loaded into any of the layers
at that location, then the window will show either the landcover, elevation, or population density.
N.B. Geo-data can be downloaded anywhere at any scale. The data sets have a much lower resolution (about 1 km per grid cell) than the background Google maps.
If the data area spans a significant fraction of the globe it will not overlay exactly with the map background; however, if you export the data and display on
Google Earth it will be aligned.
Sometimes it is necessary to zoom in/out and scroll around the area of interest when creating a 3D view in order for the Google Map server to fill in the
necessary data for our renderer.