RE: [GMLJP2] NetCDF <--> GML/JPEG2000

• To: John Caron; Sean Forde
• Subject: RE: [GMLJP2] NetCDF <--> GML/JPEG2000
• From: rlake@xxxxxxxxxxxxx
• Date: Fri, 13 May 2005 09:20:03 -0700

HI,

I agree with Simon's description - but it would not be difficult to
generalize the current coverage concept to allow the domain to be other than
a spatial-temporal region.

Ron

Sent: May 12, 2005 6:53 PM

Yes.

Perhaps the most important differences between the GML/ISO concept of
"coverage" and netCDF and allies are:

1. netCDF etc support rather generalised mappings between arrays.

Thus the "domain" of the data (the independent variable, if you like) is not

really contrained.

In contrast, a geospatial coverage is a specialisation in which the domain

must be spatio-temporal, i.e. between 1 and 4 dimensions.

As Ron points out, JP2K is even more restricted in this sense - it only

supports 2D domains.

2. There is explicit support for registering the domain of a geospatial
coverage to real-world locations - the most well-known is where the domain
is a rectified grid, but other geometries may be used which are tied to a

spatial reference system.

3. As Ron points out, an "Observation" is the act of collecting some values

associated with a target.

The "result" of an observation is essentially parallel to the "range" in a

coverage. The "target" of an observation is parallel to the "domain".

The Observation viewpoint focusses on the observation event, and is
primarily a means to access metadata associated with property values - how

they were obtained, when, by whone, etc.

This is of interest when trying to assess data reliability, and for data

insertion.

Futher down the chain, Observation/result values will often be collated into
"coverages" in preparation for some analysis, anomaly or feature-detection,

etc.

But it is very much the case that the structure of a "coverage" when
expressed as a map of the range over the domain is the same as the structure

of a an observation which maps a result to a target.

See https://www.seegrid.csiro.au/twiki/bin/view/Xmml/ObservationsAndMeasurements

for some detail.

Simon

• Follow-Ups:
  • RE: [OWS-3-SWE] RE: [GMLJP2] NetCDF <--> GML/JPEG2000
    • From: John R . Herring

• References:
  • RE: [OWS-3-SWE] RE: [GMLJP2] NetCDF <--> GML/JPEG2000
    • From: Simon.Cox