Globe-based earth browsers like GoogleEarth have turned web-based cartography into a widely accepted commodity. This success is based on the three components: The browser software itself, remote sensing data as a backdrop maps and thematic content layers. From a GRASS GIS perspective, the ability to communicate thematic content via earth browsers is a strategic means to quickly communicate findings to very large communities. This poster describes the current options to compose such thematic content layers by using GRASS GIS: Loosely coupled Keyhole Markup Language (KML) export functionalities provide the „glue“ for the seamless integration between the GIS and the earth browser.

1. Advanced KML with GRASS GIS
Peter Löwe
RapidEye AG, Molkenmarkt 30, D 14476 Brandenburg a. d. Havel, Germany, Contact: loewe@rapideye.de
Motivation
Viewshed Analysis Demonstration
Globe-based earth browsers like GoogleEarth have turned web-based cartography into a widely accepted Two alternative sites for digital
commodity. This success is based on the three components: The browser software itself, remote sensing broadcast stations towers qre
data as a backdrop maps and thematic content layers. assessed through polygon overlays
(Odenwald Region, Germany).
From a GRASS GIS perspective, the ability to communicate thematic content via earth browsers is a
Red: Spatial coverage from
strategic means to quickly communicate findings to very large communities. proposed primary site,
Green (translucent): coverage from
This poster describes the current options to compose such thematic content layers by using GRASS GIS: alternative site.
Loosely coupled Keyhole Markup Language (KML) export functionalities provide the „glue“ for the seamless Green (opaque): Special interest
integration between the GIS and the earth browser. region.
Source: P.Löwe 2010
GRASS-based KML
Workflows Satellite Image Map Demonstration
Green: GRASS modules Combined usage of of point, polygon and raster
Red: Advanced KML layers in a KMZ created from an automated script:
generation including layout. RapidEye satellite maps of the eastern Mississippi
Grey: Standard KML Delta in RGB (left) and CIR (NIR-RedEdge-R,
generation. right), including imagery metadata.
Blue: Manually edited KML
derivate from standard Source: RapidEye, 2010
workflow
Approach
GRASS GIS provides built-in support for KML export in a minimalistic way (v.out.ogr): Only vector data can
be exported in default coloring scheme.This results in a de-facto media break, since color-schemes can not
be easily sent to the globe browser from the GRASS session and would require manual editing. To mitigate
this situation, two add-on GRASS modules were created to provide enhanced support of vector export
including cartographic information (v.out.kml, Peter Löwe, 2007) and also raster map export (r.out.kml,
Hamish Bowman, 2008). References:
The current functionality includes raster-map export and the control of line width, opacity, coloring and
custom icons for vectors via general settings and attributes. It is highly effective in scripted GRASS-based r.out.kml: http://grass.osgeo.org/wiki/GRASS_AddOns#r.out.kml
standalone workflows. This approach enables automated spatial data processing, effectively shielding the v.out.ogr: http://grass.fbk.eu/grass64/manuals/html64_user/v.out.ogr.html
user from the GIS processing details, while providing KML-based results for interactive examination.
v.out.kml: http://grass.osgeo.org/wiki/GRASS_AddOnsvr.out.kml
With the ongoing development of the KML standard, the scripts continue to evolve to provide more options.
Support for timestamps and optimized access for large datasets is under development.
RapidEye Maps: http://www.rapideye.de/home/news/news-extra-page.html