Re: UML Geotiff

FYI, I received this from someone:

------------------------

I haven't seen any of Niles Ritter's java code. I thought the libgeotiff
was in C.

JAI has a TIFF reader, which can be converted into Geotiff. Go to the
geotiff web page and get the specs. It's at
http://www.remotesensing.org/geotiff/geotiff.html . It also has some
sample files (with descriptions) and some coding cookbooks.

Concentrate on TiffField 34735 and set-up a "reader" to get the geotiff
fields out of it. They are set-up the same as the TIFF fields in the
TIFFDirectory. The TIFFDirectory is in the TIFF javadocs.

Geotiff fields relate to image placement on a map. You will have to
convert the (tiff) ModelPixelTag & ModelTiePointTag or the
ModelTransformation tag. If you do the transformations, get the Java
Vector Math lib. JAI takes care of the actual image retrieval (strip
bytes,RGB, etc). As a matter of fact, you can get the geotiff image
using the (Sun) tiff examples.

The only thing is: don't use any getPixels() calls in the JAI to create
an OMRaster. I don't remember what the actual class is. It has (or had)
a sleep method in some-sort of internal producer/consumer. The only way
to tell is to do a java thread dump (Ctrl-break in DOS). It takes around
7 minutes to get all the pixels on a small image - at least it did in
the version I tested. Get the image the same way the (Sun's) JAI tiff
sample files do.

------------------------

Sounds like a geotiff reader is not that hard to implement. I'd use an
OMScalingRaster to load the image into. Anyone up for this?

Cheers,

Don

On Monday, June 3, 2002, at 05:30 AM, Norman Barker wrote:

> Hi everyone,
> I have used OpenMap alot as a user and am trying to code
> now, and am looking forward to the new release with Java3D.
>
> I have a couple of questions, has anyone tried using JAI and Niles
> Ritter's java version of libgeotiff? Or has anyone got a release of a
> different implementation of a geotiff layer.
>
> Also is there a design document for OpenMap? Any UML diagrams?
>
> Thanks for all your work with OpenMap.
>
> Norman Barker
>
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Don Dietrick, BBN Technologies, dietrick@bbn.com
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