EarthView 3D Globe Visualization for iOS
EarthView is an open-source 3D visualization of the Earth globe for iOS that uses map tiles for imagery and OpenGL ES and GLKit for rendering. I built it for a side-project that may never go anywhere, so I figured it might be educational or useful to other developers.
The project uses a quad-tree to page in map tiles that conform to the Tile Map Service standard (or, the flipped Google equivalent). The level of detail to display is determined by the estimated screen-space error of a given page.
A recent update added realistic topography to the face of the globe for realistic mountains and valleys. The data source I used is NOAA GLOBE (http://www.ngdc.noaa.gov/mgg/topo/gltiles.html) which was converted to a grayscale tileset and uploaded to MapBox.
How to Use
Move the globe around by dragging with your finger. You can flick the globe to spin it further. Zoom in and out using a pinch gesture, or by double-tapping. Tilt or rotate the globe by dragging a finger along the right or bottom edges of the screen, respectively.
There is currently no way to select which map layer is displayed at runtime. See DRAppDelegate.m to select which hardcoded layer is used.
About the Author
I build advanced airborne 3D imagers at my day job, which leaves me with the creative itch to build something a bit more tactile in my free time. Feel free to contact me (firstname.lastname@example.org or @rossanderson) if you have questions, comments, or an interesting business opportunity. Let me know if you use EarthView in your app!
The overall license for this project is BSD. TPPropertyAnimation by Michael Tyson is also BSD licensed and is included in the Source folder. Please see the license file for specific rights and restrictions.
Requirements and Dependancies
This project has no dependencies beyond the iOS 5 SDK. It has been tested to work correctly on an iPad (3rd generation) and iPhone 4.
The example application connects to various map tile services over the web such as MapBox or OpenSteetMap as defined in DRAppDelegate.m. There is no local data stored with the application, so an Internet connection on your device is required.
Bugs, Limitations, and Todos
- The terrain data appears to be mis-aligned to the map.
- The derived bounding spheres don't appear to be calculated correctly.
- There are holes in the globe at the poles because there is no map tile content there.
- The tilt control should bounce when you hit the hard stops.
- The star box should fade into a blue sky box as the user zooms the camera in.