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

[Antonio Rodriges]

I suppose it has a bit different purpose (like an efficient handling of
sparsity which is not the case with dense climate data) and I hope there is
an easier solution (I just have 3 dimensions...)

Antonio

2017-10-30 14:52 GMT+03:00 Stephen V. Mather <svm at clevelandmetroparks.com>:

> Ya, I’m not sure point clouds are at all the fix. They just address the
> dimensionality question well, though not the gridded data requirement.
>
> Cheers,
> Best,
> Steve
>
>
> [image: http://sig.cmparks.net/cmp-ms-90x122.png]*Stephen V. Mather*
> GIS Manager
> (216) 635-3243 (Work)
> (216) 339-6347 (Cell)
> --sent from phone--
>
>
>
> On Oct 30, 2017, at 07:49, Antonio Rodriges <antonio.rrz at gmail.com> wrote:
>
> Thank you for pointing to this tool.
>
> However, I thought that since PostGIS uses GDAL it may be easier to import
> such arrays, e.g. just split them onto individual 2-d grids (since PostGIS
> mainly understands 2-d grids).
>
> 2017-10-30 14:34 GMT+03:00 Stephen V. Mather <svm at clevelandmetroparks.com>
> :
>
>> 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
>>
>>
>> [image: http://sig.cmparks.net/cmp-ms-90x122.png]*Stephen V. Mather*
>> GIS Manager
>> (216) 635-3243 (Work)
>> (216) 339-6347 (Cell)
>> --sent from phone--
>>
>>
>>
>> On Oct 30, 2017, at 07:09, Antonio Rodriges <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>:
>>
>> Hi Antonio,
>>
>>
>> 2017-10-29 12:31 GMT+01:00 Antonio Rodriges <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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