[postgis-users] Handling N-d arrays in PostGIS

[Stephen V. Mather]

I don’t know if it’s the ideal tool for the job, as it’s more flexible than you need, not being a regularized grid but a point cloud, but you might look to the pgPointCloud extension: https://github.com/pgpointcloud/pointcloud

Cheers,
Best,
Steve


[http://sig.cmparks.net/cmp-ms-90x122.png]Stephen V. Mather
GIS Manager
(216) 635-3243<tel:(216)%20635-3243> (Work)
(216) 339-6347 (Cell)
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On Oct 30, 2017, at 07:09, Antonio Rodriges <antonio.rrz at gmail.com<mailto:antonio.rrz at gmail.com>> wrote:

Hello,

Thank you for the reply, however my data is slightly different. Sorry
that I did not make it clearer at the very beginning.

Actually I would like to import a dense, 3-d array of wind speed (a
time series of grids, each grid point contains the wind speed value)

The array is stored as a NetCDF file
FIles are here https://www.esrl.noaa.gov/psd/cgi-bin/db_search/DBListFiles.pl?did=61&tid=59909&vid=4298

The size of the array and its dimensions are below

dimensions:
   lat = 94 ;
   lon = 192 ;
   time = 1460;

The array

short uwnd(time,lat,lon) ;
     uwnd:long_name = "6-Hourly Forecast of U-wind at 10 m" ;
     uwnd:valid_range = -32765s, -8765s ;
     uwnd:unpacked_valid_range = -120.f, 120.f ;
     uwnd:actual_range = -38.2f, 38.07f ;
     uwnd:units = "m/s" ;
     uwnd:add_offset = 207.65f ;
     uwnd:scale_factor = 0.01f ;
     uwnd:missing_value = 32766s ;
     uwnd:_FillValue = -32767s ;
     uwnd:precision = 2s ;
     uwnd:least_significant_digit = 1s ;
     uwnd:GRIB_id = 33s ;
     uwnd:GRIB_name = "U GRD" ;
     uwnd:var_desc = "u-wind" ;
     uwnd:dataset = "NCEP/DOE AMIP-II Reanalysis (Reanalysis-2)" ;
     uwnd:level_desc = "10 m" ;
     uwnd:statistic = "Individual Obs" ;
     uwnd:parent_stat = "Other" ;
     uwnd:standard_name = "eastward_wind" ;

2017-10-30 11:04 GMT+03:00 Giuseppe Broccolo <g.broccolo.7 at gmail.com<mailto:g.broccolo.7 at gmail.com>>:
Hi Antonio,

2017-10-29 12:31 GMT+01:00 Antonio Rodriges <antonio.rrz at gmail.com<mailto:antonio.rrz at gmail.com>>:

Hello,

Whether PostGIS allow importing 3-d, 4-d, etc. arrays or only 2-d arrays?

Specifically, I have a 3-d array with axes (time, lat, lon).
Does this mean that I need to split it onto 2-d bands (lat, lon) and
import the number of bands that is equal to the number of time steps
in the 3-d array?


Which is the data source from which you import the data (e.g. textual,
etc.)?

If I've correctly understood, you have arrays where geospatial and
non-geospatial information
is present, each one providing a "dimension" of the array.

Just FYI, in PostGIS is possible to define mixed, structured data with
constructors like POINTM
and POINT, that allow to add a further dimension to the 2D/3D (respectively)
geospatial ones, that
includes a scalar information.

Hope this can help in your import, otherwise provide more information about
source data and how
you'd like to import.

Giuseppe.


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