Re: [thredds] Regularly / Irregularly gridded data

Hi Derrick,

The regular grid constraint is in fact a part of the WCS specification (at least for 1.x, which has been implemented for TDS). Under the scope section of the spec, you'll find:

"Grid coverages have a domain comprised of regularly spaced locations along 0, 1, 2, or 3 axes of a spatial coordinate reference system. Their domain may also have a time dimension, which may be regularly or irregularly spaced...


The WCS interface, while limited in this version to regular grid coverages, is designed to extend in future versions to other coverage types defined in OGC Abstract Specification Topic 6, "The Coverage Type" [OGC 00-106]."

Having said that, WCS 2.0 (freshly released a couple of weeks ago) does allow for irregular grids, which is really exciting :)

Hope that helps.



On 11/11/10 6:46 PM, Derrick.Wong@xxxxxxxx wrote:
Hi all,

I have been using THREDDS for awhile now, and have been serving
“regularly” gridded data via the WCS server. There are some datasets
which I thought were gridded but I can only GetCapabilities document
from it.

I have read the specification for THREDDS Web Coverage Service
and it says:

   1. Data files must contain gridded data.
   2. The NetCDF-Java Common Data Model must be able to identify the
      coordinates system used. Check this by opening in the Grid Panel
      of the ToolsUI
      application. There should be one or more variables shown as a GeoGrid.
   3. Currently due to WCS and GeoTIFF limitations, the X,Y and (if it
      exists) Z axes must be regularly spaced.

What exactly constitutes the Thredds definition of “regular” and
“irregular” data? Apart from using ToolsUI to check, what are the actual
specifications of regularly gridded data which can be served by THREDS WCS?

Thank you for your time.


*Derrick Wong***
Software Engineer *|* Spatial Information Services Stack (SISS) Project

Phone: +61 8 6436 8945
derrick.wong@xxxxxxxx <mailto:derrick.wong@xxxxxxxx> *|*
Address: Spatial Information Services Stack (SISS), 26 Dick Perry
Avenue, Kensington WA 6151, Australia

/The information contained in this email may be confidential or
privileged. Any unauthorised use or disclosure is prohibited. If you
have received this email in error, please delete it immediately and
notify the sender by return email. Thank you. To the extent permitted by
law, CSIRO does not represent, warrant and/or guarantee that the
integrity of this communication has been maintained or that the
communication is free of errors, virus, interception or interference.

*Please consider the environment before printing this email.*

thredds mailing list
For list information or to unsubscribe,  visit:

Pauline Mak

AODN Development Office
University of Tasmania
Private Bag 21

Ph:  (03) 6226 8586
Fax: (03) 6226 8575

  • 2010 messages navigation, sorted by:
    1. Thread
    2. Subject
    3. Author
    4. Date
    5. ↑ Table Of Contents
  • Search the thredds archives: