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<p>Hi,</p>
<p>Krigging functions are part of the SAGA Algorithms. If you do
not see SAGA in the processing toolbox, then you probably need to
activate the provider. Activate the toolbox, go to the processing
options (the wrench), Processing, Providers. You may want to
install the the Processing Saga Next Gen Provider plugin instead.</p>
<p>I don't know how they go from the tin to the raster. I imagine
they use the nearest neighbor. <br>
</p>
<p>Nicolas<br>
</p>
<div class="moz-cite-prefix">On 2021-12-09 4:57 p.m., Firstname
Lastname wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAAyYZQKfb=jAe9P481bkhk1tuNi1uJuWGsB61nwjHMi3ko8W1w@mail.gmail.com">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<div dir="ltr">Thanks for the information above, it was
very helpful and i now have a better understanding of the
interpolation process.
<div>As a follow up question, i could not find the
krigging function in the processing toolbox, only TIN and
IDW. where do i look for the krigging interpolation</div>
<div>Also, i understand the construction of delawney triangles
and veronoi diagrams now and how the veronoi cells are
constructed. What i am not clear on is, once you have
completed the interpolation and you have your delawney
triangle boundaries, how does this get translated to at
regular grid. </div>
<div>the triangular mesh is irregular, how does this get
referred to a rectangular grid? if you have a brief
description, that is adequate. </div>
<div><br>
</div>
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<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Mon, Dec 6, 2021 at 2:51 PM
Nicolas Cadieux <<a
href="mailto:njacadieux.gitlab@gmail.com"
moz-do-not-send="true" class="moz-txt-link-freetext">njacadieux.gitlab@gmail.com</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div>
<p>Hi,</p>
<p>Open the Processing toolbox panel, search for
'Krigging'. You will see multiple SAGA modules. If you
search for "interpolation", you will find IDW AND TIN
under Q modules and other methods under the SAGA module.
If you search for "grid" you will find multiple algorithms
under GDAL/Raster analysis. See <a
href="https://gdal.org/tutorials/gdal_grid_tut.html#gdal-grid-tut"
target="_blank" moz-do-not-send="true"
class="moz-txt-link-freetext">https://gdal.org/tutorials/gdal_grid_tut.html#gdal-grid-tut</a>
and <a href="https://gdal.org/programs/gdal_grid.html"
target="_blank" moz-do-not-send="true"
class="moz-txt-link-freetext">https://gdal.org/programs/gdal_grid.html</a>
for other methods. This should cover it.</p>
<p>The idea is generally to interpolate a raster surface
from points or lines containing a z field or a z value (in
3D files). After, you use Raster/Extract/Contour on this
new raster layer. You can also install the contour
plugin. That uses a point file only but I don't know the
what algorithm it uses.<br>
</p>
<p>You may find more algorithm using CrimeStat or GeoDa
softwares.<br>
</p>
<p>Hope this helps.</p>
<p><br>
</p>
<p>Nicolas<br>
</p>
<p><br>
</p>
<p><br>
</p>
<div>On 2021-12-06 1:59 p.m., Firstname Lastname wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">hello group:
<div>i want to demonstrate some of the pitfalls of
computer contouring methods with limited datasets. i
wanted to use a small dataset to demonstrate several
contouring algorithms. In particular, linear
interpolation, inverse weighted, nearest neighbour and
kriging. Are any of these built into QGIS? i do not
see any options to control the contouring in the
plugins for any options other than the default. </div>
<div>thank you if you can provide any help.<br
clear="all">
<div><br>
</div>
-- <br>
<div dir="ltr">
<div dir="ltr">Byron Veilleux, MSc. P.Geo
<div>Conjugate Geologic Services Limited</div>
<div>Calgary, Alberta Canada</div>
<div><a href="mailto:byron@conjugategeo.com"
target="_blank" moz-do-not-send="true"
class="moz-txt-link-freetext">byron@conjugategeo.com</a></div>
<div>Cell:4037108414</div>
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</blockquote>
<pre cols="72">--
Nicolas Cadieux
<a href="https://gitlab.com/njacadieux" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">https://gitlab.com/njacadieux</a></pre>
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</blockquote>
<pre class="moz-signature" cols="72">--
Nicolas Cadieux
<a class="moz-txt-link-freetext" href="https://gitlab.com/njacadieux">https://gitlab.com/njacadieux</a></pre>
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