[GRASS-user] How GRASS saves raster cell values?

GRASS GRASS user
1

I would like to rasterize a vector map with building data (including attribute data) but I am not sure how several buildings (e.g. the building areas) are acknowledged within one cell (value). For example, there is a raster resolution of 100x100 m, so I presumably get about 8-10 buildings within one raster cell.
Now the question is how does GRASS calculate the cell values based on the building theme’s attribute . Does it take the mean value? And does GRASS recognize if one building extends over more than one cell (and how?).

Regards

Chris

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2

christian Brandt wrote:

I would like to rasterize a vector map with building data (including
attribute data) but I am not sure how several buildings (e.g. the
building areas) are acknowledged within one cell (value). For example,
there is a raster resolution of 100x100 m, so I presumably get about
8-10 buildings within one raster cell.

Now the question is how does GRASS calculate the cell values based on
the building theme's attribute <area>. Does it take the mean value?
And does GRASS recognize if one building extends over more than one
cell (and how?).

There isn't much point trying to rasterise features that small.

First, the code to rasterise vectors is littered with fudges which
will move vertices by up to one cell.

Also, if multiple polygons cover a particular cell, the cell's value
will be determined by the last polygon rendered.

--
Glynn Clements <glynn@gclements.plus.com>