[Qgis-user] Re: How to draw a polygon shapefile around raster pixels?

[Saber Razmjooei]

 boesiii

Not sure how you can do it in QGIS. Someone might have already mentioned
GRASS tools to do it. These are the modules helping you to convert your
raster to vector:

r.null  >> set all the values (or range of values you want NOT to be
included in your output)

r.null map= YOURMAP setnull=-100-40

-100 is your lower band
40 is the higher band

Convert the raster to vector

r.to.vect -s input=YOURMAP output=VECTOROUTPUT feature=area

in the above command, each value will turn into a grid cell (the same size
as your region setting e.g. 5 x 5)

If you want to have all of the cells merged into one polygon, you can create
a MASK out of your raster (YOURMAP) and convert the MASK into the vector.

Cheers
Sab
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