'Re: [postgis-users] Location of highest point in each region?'

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List:       postgis-users
Subject:    Re: [postgis-users] Location of highest point in each region?
From:       Birgit Laggner <birgit.laggner () thuenen ! de>
Date:       2021-04-19 6:48:06
Message-ID: 1161460926.1084340.1618814886833.JavaMail.zimbra () thuenen ! de
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Hi Jesper, 

just from the manual: If you have the value, could you not use ST_PixelOfValue to \
extract the location? 

from the PostGIS-manual: 

ST_PixelOfValue — Get the columnx, rowy coordinates of the pixel whose value equals \
the search value. 

Regards, 
Birgit 

Von: "Jesper Kempe" <jesper.kempe@gmail.com> 
An: postgis-users@lists.osgeo.org 
Gesendet: Montag, 19. April 2021 08:34:42 
Betreff: [postgis-users] Location of highest point in each region? 

Hi 
I have loaded a DEM dataset into a Postgis raster table. And a shapefile with \
polygons for a number of regions into another table. 

For a couple of days now I have been trying to extract the height and location of the \
highest point in each of the regions. But I cannot find a way to do it. 

I am able to find the highest value in each region using ST_SummaryStats() but not \
the location (coordinates) of that value. 

Can anyone point me in the right direction how I should do this? 
It must be possible to do this in Postgis right? 

Thanks 
Jesper 

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[Attachment #5 (text/html)]

<html><body><div style="font-family: arial, helvetica, sans-serif; font-size: 12pt; \
color: #000000"><div>Hi Jesper,<br></div><div><br data-mce-bogus="1"></div><div>just \
from the manual: If you have the value, could you not use \
ST_PixelOfValue  to extract the location?<br \
data-mce-bogus="1"></div><div><br data-mce-bogus="1"></div><div>from the \
PostGIS-manual:<br data-mce-bogus="1"></div><blockquote><div> ST_PixelOfValue — Get \
the columnx, rowy coordinates of the pixel whose value equals the search value.  \
</div></blockquote><div>Regards,<br data-mce-bogus="1"></div><div>Birgit<br \
data-mce-bogus="1"></div><div><br data-mce-bogus="1"></div><div><br></div><hr \
id="zwchr" data-marker="__DIVIDER__"><div data-marker="__HEADERS__"><b>Von: \
</b>"Jesper Kempe" &lt;jesper.kempe@gmail.com&gt;<br><b>An: \
</b>postgis-users@lists.osgeo.org<br><b>Gesendet: </b>Montag, 19. April 2021 \
08:34:42<br><b>Betreff: </b>[postgis-users] Location of highest point in each \
region?<br></div><div><br></div><div data-marker="__QUOTED_TEXT__"><div \
dir="ltr">Hi<br><div>I have loaded a DEM dataset into a Postgis raster table. And a \
shapefile with polygons for a number of regions into another \
table.&nbsp;</div><br><div>For a couple of days now I have been trying to extract the \
height and location of the highest point in each of the regions. But I cannot find a \
way to do it.</div><br><div>I am able to find the highest value in each region \
using&nbsp;ST_SummaryStats() but not the location (coordinates) of that \
value.</div><br><div>Can anyone point me in the right direction how I should do \
this?&nbsp;</div><div>It must be possible to do this in Postgis \
right?</div><div><br>Thanks</div><div>Jesper</div></div> \
<br>_______________________________________________<br>postgis-users mailing \
list<br>postgis-users@lists.osgeo.org<br>https://lists.osgeo.org/mailman/listinfo/postgis-users<br></div></div></body></html>

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