Hi Jia,
Thanks for the fast response.
With the regular spatial join I’ll get the array of data of the whole
geotiff polygon. I was hoping to get the data element for specific
coordinates inside that polygon. In other words: I guess the array of data
corresponds to all the positions in the polygon, but I want to fetch
specific positions.
Thanks,
On Sun, 15 Jan 2023 at 01:09, Jia Yu <ji...@apache.org> wrote:
> Hi Pedro,
>
> Once you use Sedona geotiff reader to read those geotiffs, you will get a
> dataframe with the following schema:
>
> |-- image: struct (nullable = true)
> | |-- origin: string (nullable = true)
> | |-- Geometry: string (nullable = true)
> | |-- height: integer (nullable = true)
> | |-- width: integer (nullable = true)
> | |-- nBands: integer (nullable = true)
> | |-- data: array (nullable = true)
> | | |-- element: double (containsNull = true)
>
>
> You can use the following way to fetch the geometry column and perform the
> spatial join;
>
> geotiffDF = geotiffDF.selectExpr("image.origin as
> origin","ST_GeomFromWkt(image.geometry) as Geom", "image.height as height",
> "image.width as width", "image.data as data", "image.nBands as bands")
> geotiffDF.createOrReplaceTempView("GeotiffDataframe")
> geotiffDF.show()
>
> More info can be found:
> https://sedona.apache.org/1.3.1-incubating/api/sql/Raster-loader/#geotiff-dataframe-loader
>
> Thanks,
> Jia
>
> On Sat, Jan 14, 2023 at 9:10 AM Pedro Mano Fernandes <
> pedromor...@gmail.com> wrote:
>
>> Hi everyone!
>>
>> I'm trying to use elevation data in GeoTiff format. I understand how to
>> load the dataset, as described in
>>
>> https://sedona.staged.apache.org/api/sql/Raster-loader/#geotiff-dataframe-loader
>> .
>> Now I'm wondering how to join this dataframe with another one that
>> contains
>> coordinates, in order to get the elevation data for those coordinates.
>>
>> Something along these lines:
>>
>> pointsDF
>> .join(geotiffDF, ...)
>> .select("lon", "lat", "geotiff_data")
>>
>> Are there any examples or documentation I can follow to accomplish this?
>>
>> Thanks,
>>
>> --
>> Pedro Mano Fernandes
>>
> --
Pedro Mano Fernandes
