<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto">Hi,<div>Not sure we have access to this in QGIS but the raster to vector is based on the polygonize() function in Gdal. I see they have a fpolygonize() function also that you can call with a python script. The « f » stands for float.</div><div><br></div><div><a href="https://gdal.org/python/index.html">https://gdal.org/python/index.html</a></div><div><br></div><div>You could probably easily adapt the script found on the Gdal cookbook page.</div><div><br></div><div><a href="https://pcjericks.github.io/py-gdalogr-cookbook/raster_layers.html#polygonize-a-raster-band">https://pcjericks.github.io/py-gdalogr-cookbook/raster_layers.html#polygonize-a-raster-band</a><br><br><div dir="ltr">Nicolas Cadieux<div><a href="https://gitlab.com/njacadieux">https://gitlab.com/njacadieux</a></div></div><div dir="ltr"><br><blockquote type="cite">Le 9 nov. 2021 à 07:22, Bo Victor Thomsen <bo.victor.thomsen@gmail.com> a écrit :<br><br></blockquote></div><blockquote type="cite"><div dir="ltr">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<p>Greetings list -<br>
</p>
<p>I have a question about polygonization of a raster layer/file
with float values as pixel values</p>
<p>My raster layer contains pixel <i>float</i>-values from -0.97
to +4.78. When I run the<i> </i><i>"</i><i>Polygonize (raster to
vector)</i><i>"</i> processing algorithm I get a new layer with
nice polygons in the layer. However, all my depth values has been
converted to integers in the range from 0 - 4. And the polygons
has been dissolved in fewer and larger polygons that what I
wanted.</p>
<p>Is there a method i.e some qualifier or whatnot, that I can add
to the GDAL command-line that would classify the decimal values
from meters to centimeters, i.e I would get a polygon layer with
depth values like -0.99, -09.98 ... 4.78 (around 577 discrete
values), and a larger number of smaller polygons ?</p>
<p>I'm aware that I could take the raster layer, multiply the pixel
values with 100.0; convert to integer; create the the polygon
layer from the modified raster layer and lastly update the depth
value in the polygon layer by dividing it with 100. And yes, I can
make a processing model to do the work <br>
</p>
<p>But alas, I have hundreds of raster layers to process, so I
trying to minimize the work for processing each of these raster
files. <br>
</p>
<p> <br>
</p>
<p><br>
</p>
<pre class="moz-signature" cols="72">--
Med venlig hilsen / Kind regards
Bo Victor Thomsen</pre>
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