global but non-modulo datasets

[Jonathan Callahan <Jonathan.S.Callahan@xxxxxxxx>]

John,

A little experimenting at this end shows that you can define an axis of 
357 degrees and the applet will center the map on the valid region and 
prevent the user from scrolling the map.  If you define an axis of 358 
or 359 degrees the applet does something stupid and the selection tool 
gets stuck on the left hand side of the image.

This may be the best behavior we can provide for giving you some limits 
to convert into indices.  I believe the applet will still return this to 
you defined on -180:180 but at least this way the user is constrained to 
selecting a region where lo < hi (not traversing the 'branch cut').  
Then you should be able to convert to index space for the geoTIFF server 
request safely.

This problem displays unresolved issues in data interoperability.  
Because Ferret is aware of the modulo nature of longitude, a global 
dataset can be displayed over any 360 deg range.  In LAS we have tried 
to hide from users the dataset details (e.g. what axis is it defined on) 
so that LAS users come to expect that you can look at any range you want 
in a global dataset.   Some may be surprised that this is not possible 
when requesting geoTIFF output.


-- Jon