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<p>Hi Maria:</p>
<p>Just from the cuff, the units are pixels or meters. Try
reprojecting your source data to a projected coordinate system
(UTM, for example) and try kriging again. Set the raster
resolution to a course value that makes sense for your data to run
a test raster and then run at the final resolution you require if
you are concerned with processing time.</p>
<p><br>
</p>
<p>By using geographic corrdinates, you probably were generating a
hugh raster which caused your computer to hang.</p>
<p><br>
</p>
<p>Kirk Schmidt<br>
</p>
<div class="moz-cite-prefix">On 9/30/2021 3:03 PM, Maria Eugenia
Gomez wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CO6PR04MB7506A6985E9677BF6B0856E9FDAA9@CO6PR04MB7506.namprd04.prod.outlook.com">
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Hi,</div>
<div style="font-family: Calibri, Helvetica, sans-serif;
font-size: 12pt; color: rgb(0, 0, 0);">
I am using QGIS 3.16.9 Hannover. I want to create a surface
(with kriging) from a list of points whose SRC is WGS84. They
are in decimal degrees covering a surface of 10km x 9km. I can
see the points correctly-<br>
</div>
<div style="font-family: Calibri, Helvetica, sans-serif;
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<br>
</div>
<div style="font-family: Calibri, Helvetica, sans-serif;
font-size: 12pt; color: rgb(0, 0, 0);">
My problem comes with the "Ordinary Kriging" setup. I unchecked
"block kriging" and used the following options:</div>
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quality measure: stand. dev.</div>
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Logarithmic transf.</div>
<div style="font-family: Calibri, Helvetica, sans-serif;
font-size: 12pt; color: rgb(0, 0, 0);">
variogram model: linear</div>
<div style="font-family: Calibri, Helvetica, sans-serif;
font-size: 12pt; color: rgb(0, 0, 0);">
fit:nodes</div>
<div style="font-family: Calibri, Helvetica, sans-serif;
font-size: 12pt; color: rgb(0, 0, 0);">
search range: local</div>
<div style="font-family: Calibri, Helvetica, sans-serif;
font-size: 12pt; color: rgb(0, 0, 0);">
search directions: all directions</div>
<div style="font-family: Calibri, Helvetica, sans-serif;
font-size: 12pt; color: rgb(0, 0, 0);">
number of points: max. number of points</div>
<div style="font-family: Calibri, Helvetica, sans-serif;
font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: Calibri, Helvetica, sans-serif;
font-size: 12pt; color: rgb(0, 0, 0);">
But when I have to fill "cell size", "maximum search distance,
block size.. etc", I do not understand the units and I think
this is the problem. Which type of units should I use? I tried
to use decimal degrees units but then the number of iterations
was so high that my computer hangs.</div>
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font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: Calibri, Helvetica, sans-serif;
font-size: 12pt; color: rgb(0, 0, 0);">
Can somebody help me with this? I searched on the QGIS
documentation but it does not say anything about units.<br>
</div>
<div style="font-family: Calibri, Helvetica, sans-serif;
font-size: 12pt; color: rgb(0, 0, 0);">
Thanks in advance,</div>
<div style="font-family: Calibri, Helvetica, sans-serif;
font-size: 12pt; color: rgb(0, 0, 0);">
Maria<br>
</div>
<div style="font-family: Calibri, Helvetica, sans-serif;
font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<br>
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<pre class="moz-signature" cols="72">--
Kirk Schmidt, MScF, BScF, RPF
General Manager
Nortek Resource Solutions Inc.
26 Church Road
Sutherlands River, NS
B0K 1W0
Tel (902) 922.3607
Email: <a class="moz-txt-link-abbreviated" href="mailto:kirk@nortekresources.com">kirk@nortekresources.com</a>
Web: <a class="moz-txt-link-abbreviated" href="http://www.nortekresources.com">www.nortekresources.com</a></pre>
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