[R-sig-Geo] Making web-repository of gridded maps: NetCDF or WKT Raster?

Tomislav Hengl hengl at spatial-analyst.net
Sun Dec 13 18:29:10 CET 2009

Dear R-sig-geo,

As a part of our project (EcoGRID.nl) we have prepared some 60 thematic 
grids that we use as auxiliary predictors for species distribution 
modeling. At this stage, we would like to put the gridded maps (50/100 m 
base resolution) into some efficient sharable geo-database.

We will most probably put the data into the NetCDF format 
(http://www.unidata.ucar.edu/software/netcdf/) because it can handle 
any-dimensional array data, and because it has been in continuous 
development and widespread use for many years. NetCDF grids can be read 
relatively easy into R using the RNetCDF package (e.g. 
http://spatial-analyst.net/DATA/readNCDF.zip). Another alternative is to 
use PostGIS WKT Raster format 
(http://trac.osgeo.org/postgis/wiki/WKTRaster), but this seems to be 
still rather experimental (?).

Once we put the grids into NetCDF format. We plan to install OPeNDAP 
(http://www.opendap.org) server on top to make the files accessible 
through the web; then Geoserver (http://www.geoserver.org) or UMN 
Mapserver (http://mapserver.org) to feed a WMS from NetCDF files (raster 
data). Finally, we plan to add a simple OpenLayers interface on top of 
that (Geoserver has it built in) to allow direct browsing of the data 
and metadata (e.g. such as this one: http://africamap.harvard.edu/)

Just to be clear, we want to put the data on a server because we would 
like to run a number of operations directly on the server (via rgdal?):

1. Overlay some point data and get the values of grids (without a need 
to download the grids locally);
2. Subset/mask and resample gridded data of interest (for a given 
bounding box and proj4 string; again without a need to download the data 
3. Upscale the grids from 100 m to 250, 500 m and 1 km resolution (then 
download the upscaled grids).
4. Write/upload new grids to the database (e.g. using WebDAV).
5. Browse the grids (and metadata) via the OpenLayers.

These are only our wishes of course. We do not know if all this is 
really possible with the current software.

Any examples or comments/suggestions/experiences are welcome (before we 
start installing and testing the functionality).


Tomislav Hengl and Lourens Veen

More information about the R-sig-Geo mailing list