When we do certain kind of raster analysis like LULC , watershed delineation or any other overlay we get certain classes. We have a desire to know how much area does a particular class occupies. We also want to know what percentage of share does this particular class has in the raster.

This tutorial is the answer for all these questions. This video is about calculation of area and percentage value of each classes of a raster, LULC. The technique shown here can also be applied to any other kind of raster overlay having some classes.

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NOTE: I forgot to mention this thing have a look.
For calculating percentage of each class
"sum" / sum("sum") * 100

For calculating features count percentage
"count" / sum("count") * 100

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Copy below code
CASE
WHEN "DN" =1 THEN to_string( 'WaterBodies')
WHEN "DN" =2 THEN to_string( 'Forest')
WHEN "DN" =5 THEN to_string( 'Agriculture')
WHEN "DN" =7 THEN to_string( 'Urban')
WHEN "DN" =8 THEN to_string( 'Bare')
WHEN "DN" =11 THEN to_string( 'Shrub')
ELSE 0
END

0:00 Intro
1:49 How to convert a raster into a vector? (Vectorize)
4:18 Creating a LULC class name field
9:23 How to calculate area of each polygon features of a LULC ?
12:22 How to calculate total area of each LULC class using statistics by categories in QGIS ?
18:32 How to calculate total percentage of each LULC class using statistics by categories in QGIS?
21:16 Wrap up

Watch our other tutorials
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Election map in QGIS with qualitative data: [ Ссылка ]
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Geoprocessing tools in QGIS: [ Ссылка ]

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