I finally settled with this algorithm for queries that span the prime
meridian. If incorrect - please go ahead and comment
Assume minLon and maxLon are the longitudinal extent for input to THREDDS
server(assume 0 to 360 range)
Step 0 Calculate difference between maxLon and minLon
Step 1 - if difference of longitude (min lon, max lon) is greater than 180
Step 2 - Form two constraint expression with these extents - [0:minLon]
and [maxLon:357.5]
Step 3 - Send two queries to THREDDS server and combine the results of the
two into one file.
On Fri, Jun 3, 2016 at 9:30 PM, Roy Mendelssohn - NOAA Federal <
roy.mendelssohn@xxxxxxxx> wrote:
> Hi Ashwin:
>
> Well that is almost correct, it depends on how the data are setup. Th
> more accurate statement is that the query can not loop around any of the
> coordinate bounds. If the prime meridian is one of the longitude limits ,
> than you can not cross it in a request. but if it is not on the boundary
> than it can be crossed. So if a dataset has longitudes (0,360) you can’t
> cross it, but if it is (-180,180) you can, but you can’t cross the dateline.
>
> -Roy
>
>
>
> > On Jun 3, 2016, at 8:44 AM, ashwinD12 . <winash12@xxxxxxxxx> wrote:
> >
> > Hello,
> > I had an associate of mine inform me that when an OpenDAP
> expression's longitudinal extent spans the prime meridian then we must
> query the data on both sides of the prime meridian and join the results. Is
> that accurate ?
> >
> > Regards,
> > Ashwin.
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> Roy Mendelssohn
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> NOAA/NMFS
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