I would read the geotiff files as binary:
https://spark.apache.org/docs/latest/sql-data-sources-binaryFile.html
Then you can define a udf to extract values directly from the geotiffs. If
you're on python you can use raster.io to do that.
In java it would look some thing like this:
Integer getValue(byte[] geotiff, double x, double y)
throws IOException, TransformException {
try (ByteArrayInputStream inputStream = new
ByteArrayInputStream(geotiff)) {
GeoTiffReader geoTiffReader = new GeoTiffReader(inputStream);
GridCoverage2D grid = geoTiffReader.read(null);
Raster raster = grid.getRenderedImage().getData();
GridGeometry2D gridGeometry = grid.getGridGeometry();
DirectPosition2D directPosition2D = new DirectPosition2D(x, y);
GridCoordinates2D gridCoordinates2D =
gridGeometry.worldToGrid(directPosition2D);
try {
int[] pixel = raster.getPixel(gridCoordinates2D.x,
gridCoordinates2D.y, new int[1]);
return pixel[0];
} catch (ArrayIndexOutOfBoundsException exc) {
// point is outside the extentent
result.add(null);
}
}
}
Br,
Martin Andersson
Den ons 18 jan. 2023 kl 17:59 skrev Pedro Mano Fernandes <
[email protected]>:
> Thanks for the update, guys.
>
> I'm not ready to contribute yet.
>
> In the meanwhile, the solution could be perhaps to convert GeoTiff to
> another format supported by Sedona. If anyone has had this use case before
> or has any idea, please share.
>
> Best,
>
> On Wed, 18 Jan 2023 at 09:47, Martin Andersson <
> [email protected]> wrote:
>
>> Hi,
>>
>> I think you are looking for something like this:
>> https://postgis.net/docs/RT_ST_Value.html
>>
>> The raster support in Sedona is very limited at the moment. The lack of a
>> proper raster type makes implementing st_value impossible. We had a brief
>> discussion about that recently.
>> https://lists.apache.org/thread/qdfcvxl6z5pb7m7ky5zsksyytyxqwv8c
>>
>> If you want to make a contribution and need some guidance, please let me
>> know!
>>
>> Br,
>> Martin Andersson
>>
>> Den ons 18 jan. 2023 kl 05:45 skrev Jia Yu <[email protected]>:
>>
>>> Hi Pedro,
>>>
>>> I got your point. Unfortunately, we don't have this function yet in
>>> Sedona.
>>> But we welcome anyone who want to contribute this to Sedona!
>>>
>>> Thanks,
>>> Jia
>>>
>>> On Tue, Jan 17, 2023 at 9:11 AM Pedro Mano Fernandes <
>>> [email protected]>
>>> wrote:
>>>
>>> > Hi all,
>>> >
>>> > Any clue? Or any documentation I can refer to?
>>> >
>>> > Here goes a dummy example to better explain myself: in QGIS I can
>>> click a
>>> > point (coordinates) of the geotiff and get the value in that point (in
>>> this
>>> > case 231 of Band 1).
>>> >
>>> > [image: image.png]
>>> >
>>> > Thanks,
>>> >
>>> > On Sun, 15 Jan 2023 at 16:17, Pedro Mano Fernandes <
>>> [email protected]>
>>> > wrote:
>>> >
>>> >> 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 <[email protected]> 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 <
>>> >>> [email protected]> 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
>>> >>
>>> >
>>> >
>>> > --
>>> > Pedro Mano Fernandes
>>> >
>>>
>>
>>
>> --
>> Hälsningar,
>> Martin
>>
>
>
> --
> Pedro Mano Fernandes
>
