[Mapserver-dev] Advanced support of grid format (visualization, interrogation, analysis)

[Claude Philipona]

Hello,

What is exactly the state of grid format handling in Mapserver? Present and
near feature. We have some people asking for some "advanced" features, with
fundings available. I don't know if somme of the needs are alreday
available or planned...

Here is a first rough description of their needs:

For GIS application, there are several models for representing the real
world (object based, field based) : simple vector, topological vector,
TIN, raster,...  Each of these models have advantages and drawbacks and
are more suited for particular problems (topological vector for
utilities management, raster for DTM analysis, etc.).  Raster format is
often used for background data (orthos, satellite,...) but can also be
used for all kind of continous data (visualisation, interrogation,
analysis for : DTMs, slope, orientation, convexity, radiation data,
pollution, income,...) and discrete data (soil occupation,...)

All web mapping solutions include the support of simple vector
(visualisation, interrogation) and raster (visualisation) ? but few (or
none) include the complete support for raster data (interrogation,
analysis).  In desktop or professional GIS, these functions are included or
in extensions (Spatial Analyst for Arcview, Vertical Mapper for MapInfo,
etc.). The objective would be to extend Mapserver to support simple
analysis function for raster (or grid) data (interrogation first,
analysis). Mapserver uses GDAL lib that supports some grid formats
(Arc/Info Binary Grid (.adf), Arc/Info ASCII Grid, Military Elevation Data
(.dt0, .dt1), GRASS Rasters, USGS ASCII DEM (.dem), ?).
The objective of the developpement would be to add to Mapserver
the possibility to support visualisation, interrogation (and eventually
simple analysis) for continuous data. The objective would not be to
develop complex analysis functions available in desktop or professionnal
GIS (at first) but to add some basic functions to present the results of
these analysis. 
Mapserver could return the pixel value for gridded data (elevation, slope,
pollution concentration, average income,..). Simple function allowing to
get information for a gridded format (height in the example below). We
could use this function to build a more sophisticated function like a cross
section.

This  developpement could be funded by several Mapserver users. It could
give Mapserver an interesting competitive advantage.

These developpements should be done conforming to OGC and ISO standards
: there are many initiatives addressing portions of the overall scope of
this Topic Volume. Important among them is the ISO TC/211 initiative to
add a work item to address raster and image data types. OGC and ISO
TC/211 intend to work closely to achieve common specifications.


Would you have interest in adding such features in Mapserver?

Claude