KML responses for Hyrax

From OPeNDAP Documentation

KML Output From Hyrax


The Data Access Protocol provides a way to transfer structured data into sophisticated analysis tools without first requiring that the data be packaged in particular format like TIFF which is so specialized it can only be practically used for a limited set of purposes. Instead DAP uses a very general self-describing format that can encode virtually anything stored in or processed by a computer. However, there are many applications now available that expect georeferenced data and can at least display such data if it’s encoded in one of several ways. While the main emphasis of OPeNDAP has been to provide data for analysis, these newer display applications are important tools for many users (and potential users) of our software. That is, even though ‘display’ of data has not be a primary focus of our work up to now, that doesn't mean it’s not important.


We can support a wide variety of network-aware display applications for georeferenced data by combining the ability to render data as a GIF, JPEG or TIFF image with an encoding of the georeferencing information for that image in KML. Many of the emerging display applications can render data encoded in these ways. It is possible that our our work on support for WCS can be leveraged to produce these types of responses: We will take existing software which uses semantic web tools to build WCS responses from existing metadata and use that to power a ‘.kml’ response that can combine the KML document with a rendering of the data it describes in one of a set of formats like GIF, JPEG or TIFF. We can use any of our ‘standard tricks’ for encoding the return types in a URL because for these display applications, the URL is essentially an opaque object used to refer to data.


Applications that would be able to display information from our servers includes: Google Earth, Google Maps, Google Maps for mobile devices, NASA WorldWind, ESRI ArcGIS Explorer, Adobe PhotoShop, AutoCAD, and Yahoo! Pipes.

To do:

  • How are data typically returned by KML so that they are useful to the clients named above? That is, how is a data set like a climatology returned so that it can be displayed on/over/with Google Earth?
  • Do the clients above already use a standard ‘KML request’ URL? If so, we should support that.
  • Read over the KML Reference doc at