Wednesday, 13 March 2013

Visualizing geodata in 3D

Page Redirection

This blog has moved to a new home, if you are not redirected automatically, follow the link to stressdriven.com


After spending some time working on the Bavaria maps pages (both the Earth and Maps pages work now!), I recently went in search of a way to project the same data in a vector format. At the moment I use the GDAL library (specifically gdalwarp and gdal2tiles) to convert georeferenced .tiff files to a .png format for projection in Google Earth (GE). These are raster files, just the same as the .jpg's that come from your digital camera, and each pixel is assigned a different colour. Using the data in this way has some issues, however, as the resolution of the images is limited, there's no way to attach metadata, and serving up all the image files puts a reasonable load on the server.... In contrast, vector formats allow us to define a shape by coordinates, then tell the computer a texture or colour to fill the shape, and  present the same data with essentially has no resolution limits (though it of course depends on the accuracy of the data collection). In addition vector files can contain metadata with links to external webpages, and are usually about 10% the size of the raster images. 

After passing through OneGeology.org, I landed at the GNS GeoServer website. OneGeology is one of those 'logical' collaborative efforts much like Wikipedia or OpenStreetmap for geological maps... for some time now, Geological data has been provided online using the .wms format as a means of connecting remotely served geological data to whatever GIS software you're running on your PC (see here for an example). It's really a great step forward, I think you could say that this initiative now provides geological data of the whole world at some resolution for free. It is, however, still a bit slow and somewhat disorganized at the moment, at least on the OneGeology portal... But as it's a true cutting-edge combination of science and IT, I think the fact that it's there is really fantastic.

The OneGeology portal links .wms data from various servers around the world, one of which is located at GNS in New Zealand. While I'm new to this, the GNS site is one of the best geodata services I've come across. The portal (once you click on Data>layer preview) provides access to 1:1M and 1:250k geodata for the whole country in a wide range of formats... including .kml for GE. This can be accessed as network links streamed off the server (for GE, first download the .kmz file by clicking here), or (for example) as a .kml file to download to your computer (this is a bit faster, check the portal). 

Google Earth screenshot showing vector-based geology of the Mt Cook region 
(data credit: GNS & Google)

I'm told by the guys and girls at GNS that the data-serving side is a true 'work in progress' (a client upgrade will happen next week), and I think the future looks exciting for the users throughout the geoscience world.