** This project is still in development **
This is a solution to the 2013 International Space Apps Challenge "Earth Tiles". The challenge is to create a service, for developers, which provides access to satellite derived tiles at various scales. These tiles would be used for various projects similar to OpenLayers applications, some of which might resemble Google Maps or MapQuest.
Nathan Crock - mathnathan@gmail.com
Olmo Zavala - osz09@fsu.edu
Sam Rustan - samrustan@gmail.com
- Ubuntu 12.04, 12.10, 13.04
GDAL-1.9 - Geospatial Data Abstraction Library
Our solution OpenTiles is more of a service than a product. Currently it is a simple implementation intended as a proof of concept demonstrating the 5 main components of the project. We now explain how it would operate at a production scale.
Let us take a very large storage system with no satellite data. This is the backend of OpenTiles. Python scripts will take care of the first 3 components.
A script will constantly query the databases and servers where satellite data is stored. If the scripts find a data file that that is not on the local drive or has been updated, it will download it. This first component ensures all the data on the backend of OpenTiles is current.
Satellite observations are stored in various formats. While they all have their benefits a collection of files in a more unified, GIS friendly format, would be more practical. After the data has been downloaded it is converted from its native type, most commonly NetCDF and HDF, into a Geotiff (Gtiff) file. We use the GDAL library for conversions.
The magic of Google Earth and other earth observation data viewers is in the tiles and pyramids. One Gtiff could be laid over an earth model but it could only be viewed at that one scale. Tiling a Gtiff and creating a pyramid of different scales, allows the user to zoom in and out of the data in a more natural way. We use the GDAL to create the various pyramids and tiles.
Once the pyramids are obtained, we are using the Geoserver REST interface to upload them into Geoserver. Specifically, we are using the Geoserver Manager java library to read the contents of the pyramids and upload them into Geoserver automatically. Once the pyramids are uploaded into Geoserver they can be served as images using the WMS standard (for OpenLayers, Leafleat, etc.), kml files (for Google Earth) and GeoTiff files (for GIS).
For visualizing the tiles that get uploaded into Geoserver, we are cofiguring a web site that displays all the layers available in the server and it allows the user to change the transparency of the layers, choose which layers to display, download the layer as kml and Geotiff format and zooming in and out of the map in a similar interface that Google maps does it. All these without any external intervention.