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

• To: Ron Lake <rlake@xxxxxxxxxxxxx>
• Subject: Re: [GMLJP2] NetCDF <--> GML/JPEG2000
• From: John Caron <caron@xxxxxxxxxxxxxxxx>
• Date: Mon, 16 May 2005 10:27:56 -0600

Ron Lake wrote:

Hi,

There are two different issues combined here.

1. Integer vs floating values.

2. Dimensionality of the coverage

*Integer vs floating values:*

JPEG 2000 offers support for integers only. It is not clear that this is a serious constraint since any observation must have only finite precision and hence can be scaled. This may be a pain, but it is common in all measurement systems.

Is there a standard way to specify scale and offset values?

*Dimensionality of the coverage:*

In general a coverage can be seen as a function *X* = f(*Y*). The dimension of X can be some N (N=0,1,2, 3, 4 .. ). With the current GMLinJP2K specification, the dimensionality of Y is 2 – that is at each point *p* on a 2D surface (e.g. surface of the earth) we can have vector quantities *X(p)* = (X1, X2, .. Xn) where each Xi will be in a different JPEG 2000 codestream.

So for representation of measurement information the restriction of GMLJP2K is that it does not allow the points *p *to be in a volume – note that the surface on which *p* lies can be in 3-space however. This is not really a restriction of JPEG 2000, however, and I think we can extend the GML description to allow the description of functions (as above) over multi-dimensional “volumes”.

Thanks for all the info, its very interesting !

• References:
  • RE: [GMLJP2] NetCDF <--> GML/JPEG2000
    • From: rlake