Dealing with Geospatial Images is the problem you are now solving.  No
doubt of that.  Images have an additional layer of meaning on top of the
simple "position-value" relationship of a Coverage. :)

I would actually argue for factoring the additional layers of meaning
entirely out of Coverage (because none of the stds have it there.)  Perhaps
a very simple GeospatialImage interface with three attributes is enough:
getValueCoverage(), getRenderedCoverage(), getPhysicalUnitsCoverage().
Down the road we could add a getIsomorphicImage()/getPerspectiveImage(),
which takes the coverage back and forth through the sensor's geometric
model.

> As said previously, the enumeration is not about spatial resampling
> but could be
> understood as "kind of units of measurement" where the enumeration
> of "kind" is
> driven by Image I/O and rendering restrictions in Java:
>
>  GEOPHYSICS: are my data in some units I can use for calculation?
>  RENDERED:   are my data in some units compatibly with Java2D
restrictions?

Ahh, but this enumeration does collapse two unrelated concerns into a
single attribute.  Think of it this way: say you have a "Geophysics"
coverage AND a ColorModel has also been specified.  You can then perform a
spatial query (evaluate()) to retrieve "rendered" data OR to retrieve the
actual data value.  Arc/Info does both.  Let us not become inferior to
Arc/Info. :) Potentially, a coverage could have a third response to
evaluate(): the raw data value in the file (different than the geophysical
value if a transformation has been applied.)

The same coverage has three different responses depending on the type of
information requested.

> etc. Because it is quite Java-specific, I do not expect to see them in an
> international standard.

Ahhh, but the notion of "data" vs. "a rendering of data" is already in the
standards.  This is the "Geospatial Image" concept found spread across
19101-2, 19115-2, 19129 (dead), and 19130 (pending).  Specification of a
rendering method is in 19117.  The "Image" concept is not formalized to the
point where we could or should stick it in GeoAPI, but it roughly equates
to "data" + "portrayal" = "Image".  This is not a Java specific thing.  I
sent out a document summarizing this Image notion about a week ago, if
you're interested.


I can't believe I said "Ahhh, but..." twice in one email. :)

Bryce


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