[Esip-documentation] Request for ACDD global attributes for geospatial data resolution

Mon Aug 6 11:53:10 EDT 2018

Dear Esip-documentation members,

I am trying to follow-up on any action that may have been taken regarding 
my request for geospatial data resolution attributes. See my message below 
for potential definitions for the new attributes you discussed.

I see the page you created has not been updated. Has any other action been 
take to move this along?  I know this is a volunteer community, I would be 
happy to add my definitions to the page if that would move things along, I 
didn't do it at the time because I wasn't sure what protocol would be if 
I'm not an official member of your working group. But after that, I 
wouldn't know what the next steps would need to be.

If some action has been taken and I just don't see it on-line, please let 
me know where I can find it.

Thank you again for the thoughtful consideration you have given to my 
request.

Mary Jo

On Thu, 26 Jan 2017, Mary Jo Brodzik via Esip-documentation wrote:

> Date: Thu, 26 Jan 2017 15:32:42 -0700 (MST)
> From: Mary Jo Brodzik via Esip-documentation
>     <esip-documentation at lists.esipfed.org>
> Reply-To: Mary Jo Brodzik <brodzik at nsidc.org>
> To: esip-documentation at lists.esipfed.org
> Subject: [Esip-documentation] Request for ACDD global attributes for
>     geospatial data resolution
> 
>
> Dear Esip-documentation members,
>
> Thank you for the discussion of my request at Monday's telecon, I apologize 
> for missing the telecon.  I just listened to the youtube recording of it, 
> which was useful.
>
> In the time since my request, I had to start producing data, so I took the 
> existing geospatial_lat/lon_resolution practices as my model.
>
> I actually created my files with the attributes you suggested at the meeting, 
> e.g.:
>
> geospatial_x_resolution = "3125.00 meters" ;
> geospatial_y_resolution = "3125.00 meters" ;
>
> It did not occur to me to populate and set geospatial_x_min/max or 
> geospatial_y_min/max; I reasoned that these were covered by the x/y dimension 
> variable bounds.  However, in the spirit of giving the user of my data set 
> some intelligible information in the global attributes, I also populated the 
> lat/lon bounds like this:
>
> geospatial_bounds_crs = "EPSG:6931"
> geospatial_lat_min = 0.
> geospatial_lat_max = 90.
> geospatial_lon_min = -180.
> geospatial_lon_max = 180.
>
> I realized that this mixed mensurations a bit, since I did not populate 
> attributes for (nonsensical, in my case) geospatial_lat/lon_resolution.
>
> I think that your proposed new attributes geospatial_x/y_resolution/min/max 
> would definitely meet my use case.
>
> As for definitions for your minutes page at:
>
> http://wiki.esipfed.org/index.php/Documentation_Cluster_Minutes_2017-01-23
>
> may I suggest the following definitions for a beginning point (modified from 
> the analogous ACDD lat/lon attributes):
>
> geospatial_x_min: Describes leftmost limit for projected data x dimension in 
> a left-handed Cartesian plane; specifies the lowest x dimension value covered 
> by the dataset.
>
> geospatial_x_max: (replace leftmost/lowest with rightmost/highest)
>
> geospatial_y_min: Describes bottommost limit for projected data y dimension 
> in a left-handed Cartesian plane; specifies the lowest y dimension value 
> covered by the dataset.
>
> geospatial_y_max: (replace bottommost/lowest with uppermost/highest)
>
> geospatial_x_resolution: Information about the targeted spacing of projected 
> data points in x dimension. Recommend describing resolution as a number value 
> followed by the units. Example: '3125.00 meters'
>
> geospatial_y_resolution: (replace x with y)
>
> Regarding your question about how similar the projected data case is to the 
> swath data case:  I would say that a rectangular array of projected data is 
> different from swath data, because the spacing between adjacent pixels across 
> the array is fixed in map coordinates, e.g. from one pixel to the next in my 
> data, the spacing is always 3.125 km in the map coordinates (the projected 
> plane).  Depending on the projection, the correspond location distances can 
> and will be different on the sphere, and in terms of latitute or longitude, 
> but in map coordinates it is a single number and does have meaning for a 
> user.  I'm using the term "map coordinates" as in the left-handed Cartesian 
> plane in the second figure of this document:
>
> https://nsidc.org/support/41976964-Points-Pixels-Grids-and-Cells-A-Mapping-and-Gridding-Primer-
>
> Thank you for your time and consideration, I will be happy to answer any 
> other questions about my use case if they arise.
>
> Mary Jo
>
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> Mary Jo Brodzik, Senior Associate Scientist, 303-492-8263
> NSIDC/CIRES, Univ. of Colo. at Boulder, 449 UCB, Boulder, CO 80309-0449
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> "We cannot solve our problems with the same thinking we used
> when we created them."  --Albert Einstein
> _______________________________________________
> Esip-documentation mailing list
> Esip-documentation at lists.esipfed.org
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>

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Mary Jo Brodzik, Senior Associate Scientist, 303-492-8263
NSIDC/CIRES, Univ. of Colo. at Boulder, 449 UCB, Boulder, CO 80309-0449
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^