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<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">Hi Ashley,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">The possibility to return negative horizon values was introduced here:<o:p></o:p></span></p>
<p class="MsoNormal"><a href="https://github.com/OSGeo/grass/commit/688d5885557f22c7ea6618dcac3ddfbfc764731a#diff-5ce8290f429502e23efaf9ebdc18bd2b"><span lang="EN-US">https://github.com/OSGeo/grass/commit/688d5885557f22c7ea6618dcac3ddfbfc764731a#diff-5ce8290f429502e23efaf9ebdc18bd2b</span></a><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN-US">The output with the d-flag is azimuth degree (-90 – 90, where 0 is parallel with the focal cell).<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">So, from my understanding, negative values indicate horizon height below the cell it is computed from.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Maybe the manual could be a bit more specific here…?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Cheers<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Stefan</span><span lang="EN-US" style="mso-fareast-language:EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> grass-user <grass-user-bounces@lists.osgeo.org>
<b>On Behalf Of </b>Ashley Cale<br>
<b>Sent:</b> tirsdag 26. mai 2020 21:16<br>
<b>To:</b> grass-user@lists.osgeo.org<br>
<b>Subject:</b> [GRASS-user] East/West Horizons Giving Negative Numbers<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US"> Hello Everyone! <o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US">Can help me figure out what's wrong with my east and west horizon calculations?<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US">I am trying to compute my east and west horizon angle from my DEM using the command r.horizon. My output raster contains negative numbers and it's my understanding that the range of output values should be between 0 and
360. I used -d to make sure that my output is in degrees rather than radians. <o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US">Can anyone help me solve this problem? Or point me in the right direction?<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US">Thank you for the help! <o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US">Ashley <o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US">Here is the </span><a href="http://r.info/" target="_blank"><span lang="EN-US">r.info</span></a><span lang="EN-US"> output from my generated east horizon raster.<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US" style="font-size:11.5pt;font-family:"Arial",sans-serif;color:#1D1C1D"> |----------------------------------------------------------------------------|<br>
| |<br>
| Type of Map: raster Number of Categories: 0 |<br>
| Data Type: FCELL |<br>
| Data Units: degrees Vertical datum: (none) |<br>
| Rows: 7532 |<br>
| Columns: 5860 |<br>
| Total Cells: 44137520 |<br>
| Projection: UTM (zone 10) |<br>
| N: 4543151.24515692 S: 4317194.98362237 Res: 29.99950366 |<br>
| E: 759846.34683197 W: 584057.70444841 Res: 29.99806184 |<br>
| Range of data: min = -90 max = 78.47394 |<br>
| |<br>
| Data Description: |<br>
| generated by r.horizon |<br>
| |<br>
| Comments: |<br>
| r.horizon -d elevation="dem30m@PERMANENT" direction=0 start=0.0 end=\ |<br>
| 360.0 output="east" distance=1.0 file="-" |<br>
| |<br>
| Horizon view from azimuth angle 0.00 degrees CCW from East |<br>
| |<br>
+----------------------------------------------------------------------------+<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US" style="font-size:11.5pt;font-family:"Arial",sans-serif;color:#1D1C1D"><o:p> </o:p></span></p>
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