[GRASS-user] NEWBIE: Time required to develop Google Earth-like GIS App??

Hamish hamish_nospam at yahoo.com
Thu Oct 19 06:06:37 EDT 2006

> I am evaluating alternative GIS tools for a research project. The
> starting point for our research requires a Google Earth like interface
> - pan, tilt, zoom on raster images, annotation creation, and data
> layers.

GRASS's NVIZ is fine for this. If you want the raster flat, no
z-component for elevation, create a new constant surface and use your
raster for the "color" attribute. It is nice to use a real elevation
raster though, but again you can drape your raster over it with the
color attribute in NVIZ's raster panel. e.g. drape LANDSAT over a SRTM
elevation layer. (r.in.wms, r.in.onearth [from the wiki addons])

Also you can export with r.out.vtk and friends to many other
visualization softwares like Paraview or use r.out.v5d for Vis5D.

The VisIt software was mentioned the other day, it should be able to
read GRASS maps directly via GDAL.  http://www.llnl.gov/visit/

> From looking thru the website it is difficult to immediately tell if
> all of this is available with GRASS "out of the box" -- with or
> without using NVIS or QGIS.

NVIZ is "out of the box" with GRASS for the most part.

 -download grass & the spearfish sample data set.
 -start it up.
 -g.region rast=elevation.10m
 -nviz elevation.10m

and you're away. Very easy to get started.

QGIS is strictly 2D only, AFAIK.

> Beyond this, a secondary capability I am looking for is a 4D feature,
> allowing the user to move a time slider (or hit a "play" button) to
> view raster imagery (and annotations) collected over time.

Yes, NVIZ does nice keyframe animations and can export directly to MPEG.

have a look at the example on the Keyframe animator help page:

> I have used KML/Google Earth to do this at least with annotations, and
> it seems to work  well -- that said, Google Earth is not an open
> system. Any information or guidance would be most appreciated.

annotations are harder, but possible. That is something which exists but
has some rough edges in NVIZ. Mostly through lack of testers I think.
(Simple site markers are fine, I'm talking about north arrows, scale
bars, and text labels)


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