[Qgis-user] Raster to Vector polygons

[Nicolas Cadieux]

Hi,
There are multiple ways to do smooth the line.  One way would be to use the smooth function as shown in the link below.
https://gis.stackexchange.com/questions/311004/smoothen-line-vector-qgis

The reason you are seeing square lines is because your raster consists of square pixels.  If you are seing something smooth, it’s because of your rendering options only. 

If the option above does not work, write back.  I think you can use a mixture of vector ”densify” then “generalize” or “smooth” or “simplification”  algorithm to do that.  Search for those termes in the processing tool box.  Vector densification will increase the amount of nodes on your lines.  Then, you can smooth, simplify or generalize your lines. I think I use v.generalize in the past.  I would need to test. I’am not in from front of  a computer now.

Nicolas Cadieux
https://gitlab.com/njacadieux

> Le 1 févr. 2021 à 13:14, upland at mcsnet.ca a écrit :
> 
> 
> Hello
> I’ve been trying to figure out a way to convert Raster slope catagories into vector polygons.  I classify a raster surface model into slope classes giving nice curvy polygons on the raster with the colors to differentiate the different classes.  I’ve tried using the polygonize raster to vector but it makes a whole bunch of square or rectangular polygons that don’t match up at all with my raster layer style.  I was hoping to find something that would create polygons that are exactly reflective of what the raster looks like with the classes and colors. Any ideas would be great.
> Thank you
> Normand
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