[postgis-devel] ST_SetValues (Generating raster from point data)

[Rémi Cura]

Sorry,
I messed up between projects.
Here is the correct file:
https://github.com/Remi-C/Postgres_Day_2014_10_RemiC/blob/master/Point_Cloud/Patch_to_raster/patch_to_raster_all_pixels.sql

Cheers,
Rémi

2014-11-12 21:46 GMT+01:00 David Haynes II <dahaynes at umn.edu>:

> Sorry, I don't think the link that you sent has the rc_Patch2Raster_arar
> function.
> This is my current stumbling block
>
> On Tue, Oct 28, 2014 at 12:37 PM, Rémi Cura <remi.cura at gmail.com> wrote:
>
>> Hey,
>> I wrote some code for this
>> Check :
>> https://github.com/Remi-C/Postgres_Day_2014_10_RemiC/blob/master/Point_Cloud/Patch_to_raster/patch_to_raster.sql
>>
>> I do a little more because I convert a pcpatch,
>> but you could take the part that takes a table of attributes (X,Y,Z,
>> whatever) and convert it to a raster.
>>
>> ST_Setvalues is the fastest way  I found,
>>  but it is still *very *slow
>> I would advice to do this outside db or with efficient python/C code.
>> (for instance python-gdal ?)
>>
>> Cheers,
>> Rémi
>>
>> 2014-10-28 18:04 GMT+01:00 David Haynes II <dahaynes at umn.edu>:
>>
>>> Hello,
>>>
>>> I am hoping someone can help point me in the correct direction on this
>>> problem. I am trying to take a table of point data and generate a raster,
>>> using some NOAA data. These are the steps that I have taken so far.
>>> Everything is fine until step 4.
>>> The ST_SetValues does not work as I have currently implemented. Because
>>> each time a value is assigned it generates another raster.
>>> The examples I have seen using ST_SetValues require each recordset to be
>>> appended to each other. Does anyone have any knowledge about other psql
>>> functions that will allow me to transpose the recordset or append
>>> recordsets together. I am considering writing a custom function to do the
>>> task.
>>>
>>> 1. Convert text to geometry value
>>> 2. Determine raster extent using convexhull.
>>> 3. Generate raster using ST_AsRaster
>>> 4. Set raster cell values using ST_SetValues
>>>
>>> with noaa_raster as
>>> (
>>> select ST_AsRaster(p_bound.geom, 3.75::float8, 2.5::float8, '32BF', 1,
>>> 0) as rast
>>>  from (
>>>   --Generate polygon extent from all points
>>>   SELECT st_convexhull(ST_Collect(base.geom)) as geom
>>>   FROM (
>>>   --Converts text to geometry
>>>   select p.grid_id, ST_geomfromtext('POINT(' || p.longitude || ' ' ||
>>> p.latitude || ')',4326) as geom, p.value
>>>   from noaa p
>>>   ) base
>>>   ) p_bound
>>> )
>>> --distances are changed to make sure we fine the centroid of each raster
>>> cell
>>> select r.rid, p.grid_id, ST_SetValues(r.rast, 1,
>>> ARRAY[ROW(ST_geomfromtext('POINT(' || p.longitude + 1.875 || ' ' ||
>>> p.latitude - 1.25 || ')',4326), p.value)]::geomval[], True ) as rast
>>> from noaa p, noaa_raster r
>>>
>>>
>>> see
>>> http://postgis.net/docs/manual-dev/RT_ST_SetValues.html
>>>
>>> --
>>> David Haynes, Ph.D.
>>> Research Associate Terra Populus
>>> Minnesota Population Center
>>> www.terrapop.org
>>>
>>> _______________________________________________
>>> postgis-devel mailing list
>>> postgis-devel at lists.osgeo.org
>>> http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-devel
>>>
>>
>>
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>>
>
>
>
> --
> David Haynes, Ph.D.
> Research Associate Terra Populus
> Minnesota Population Center
> www.terrapop.org
>
> _______________________________________________
> postgis-devel mailing list
> postgis-devel at lists.osgeo.org
> http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-devel
>
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