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<p class="MsoNormal">Even,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">That appears to have “just work”!<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><sounds of bowing><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Jesse<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><b><span style="color:black">From:
</span></b><span style="color:black">Even Rouault <even.rouault@spatialys.com><br>
<b>Date: </b>Wednesday, May 8, 2024 at 1:15</span><span style="font-family:"Arial",sans-serif;color:black"> </span><span style="color:black">PM<br>
<b>To: </b>Meyer, Jesse R. (GSFC-618.0)[SCIENCE SYSTEMS AND APPLICATIONS INC] <jesse.r.meyer@nasa.gov>, Meyer, Jesse R. (GSFC-618.0)[SCIENCE SYSTEMS AND APPLICATIONS INC] via gdal-dev <gdal-dev@lists.osgeo.org><br>
<b>Subject: </b>[EXTERNAL] Re: [gdal-dev] SQL / gdal_get_pixel_value tips requested</span><span style="font-size:12.0pt;color:black"><o:p></o:p></span></p>
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<p>Jesse,<o:p></o:p></p>
<p>the answer lies in exploring available Spatialite SQL functions: <a href="https://www.gaia-gis.it/gaia-sins/spatialite-sql-5.1.0.html">
https://www.gaia-gis.it/gaia-sins/spatialite-sql-5.1.0.html</a><o:p></o:p></p>
<p>ST_Centroid() returns a Point geometry. You may get its coordinates with ST_X() and ST_Y(). I suppose you'd need to use a sub-select construct to get things working, like<o:p></o:p></p>
<p>SELECT gdal_get_pixel_value(path, band_num, 'georef', ST_X(centroid), ST_Y(centroid)) FROM (SELECT ST_Centroid(geometry) AS centroid FROM ds) x<o:p></o:p></p>
<p>untested obviously!<o:p></o:p></p>
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<p class="MsoNormal">Le 08/05/2024 à 19:09, Meyer, Jesse R. (GSFC-618.0)[SCIENCE SYSTEMS AND APPLICATIONS INC] via gdal-dev a écrit :<o:p></o:p></p>
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<p class="MsoNormal">Hi,<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">I’m wanting to execute a SQL query on a vector database like:<o:p></o:p></p>
<p class="MsoNormal" style="line-height:13.5pt;background:#2D2A2E"><span style="font-size:9.0pt;font-family:Menlo;color:#FCFCFA">vector_mem_ds</span><span style="font-size:9.0pt;font-family:Menlo;color:#939293">.</span><span style="font-size:9.0pt;font-family:Menlo;color:#A9DC76">ExecuteSQL</span><span style="font-size:9.0pt;font-family:Menlo;color:#939293">(</span><i><span style="font-size:9.0pt;font-family:Menlo;color:#78DCE8">f</span></i><span style="font-size:9.0pt;font-family:Menlo;color:#FFD866">"select
ST_Centroid(GEOMETRY) as cnt, gdal_get_pixel_value('</span><span style="font-size:9.0pt;font-family:Menlo;color:#AB9DF2">{</span><span style="font-size:9.0pt;font-family:Menlo;color:#FCFCFA">raster_fp</span><span style="font-size:9.0pt;font-family:Menlo;color:#AB9DF2">}</span><span style="font-size:9.0pt;font-family:Menlo;color:#FFD866">',
</span><span style="font-size:9.0pt;font-family:Menlo;color:#AB9DF2">{</span><span style="font-size:9.0pt;font-family:Menlo;color:#FCFCFA">ndvi_band_num</span><span style="font-size:9.0pt;font-family:Menlo;color:#AB9DF2">}</span><span style="font-size:9.0pt;font-family:Menlo;color:#FFD866">,
'georef', cnt.STX, cnt.STY) from ds"</span><span style="font-size:9.0pt;font-family:Menlo;color:#939293">,</span><span style="font-size:9.0pt;font-family:Menlo;color:#FCFCFA">
</span><i><span style="font-size:9.0pt;font-family:Menlo;color:#FC9867">dialect</span></i><span style="font-size:9.0pt;font-family:Menlo;color:#FF6188">=</span><span style="font-size:9.0pt;font-family:Menlo;color:#939293">"</span><span style="font-size:9.0pt;font-family:Menlo;color:#FFD866">SQLITE</span><span style="font-size:9.0pt;font-family:Menlo;color:#939293">")</span><o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">In particular, I want to use the geometry’s centroid for gdal_get_pixel_value, but the latter function takes two parameters, and ST_Centroid provides 1 return value (a compound type Point), so I am hoping for some way to unpack this into
the form necessary expected from get_pixel_value. Apparently some GIS query engines do expose a STX and STY field but that’s if you trust random google results. But as is this fails.<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">Is this possible largely as-is?<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">Thanks,<o:p></o:p></p>
<p class="MsoNormal">Jesse<o:p></o:p></p>
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<br>
<o:p></o:p></span></p>
<pre>_______________________________________________<o:p></o:p></pre>
<pre>gdal-dev mailing list<o:p></o:p></pre>
<pre><a href="mailto:gdal-dev@lists.osgeo.org">gdal-dev@lists.osgeo.org</a><o:p></o:p></pre>
<pre><a href="https://lists.osgeo.org/mailman/listinfo/gdal-dev">https://lists.osgeo.org/mailman/listinfo/gdal-dev</a><o:p></o:p></pre>
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<pre>-- <o:p></o:p></pre>
<pre><a href="http://www.spatialys.com/">http://www.spatialys.com</a><o:p></o:p></pre>
<pre>My software is free, but my time generally not.<o:p></o:p></pre>
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