[GRASS-user] v.to.db area calculations

James Duffy james.philip.duffy at gmail.com
Thu May 18 07:22:48 PDT 2017


I'm trying to calculate the area of a polygon using v.to.db as follows
(through R):

*execGRASS("v.to.db", flags = c("p","quiet"), parameters = list(map =
"test", units = "meters", option = "area", separator = "comma"),intern =
I assume that the output of this command will be a meters squared
calculation of the area inside the polygon 'test'.

However, in QGIS, I manually calculated the area the they do not match.
QGIS (which I believe to be true) shows 0.128m2, and the output from
v.to.db shows 22.42226m2.

I am working in WGS84.

Can anyone shed some light on how v.to.db calculates area and why it might
be going wrong please?

Thank you


*James Duffy*
PhD Researcher
Environment and Sustainability Institute
Penryn Campus
University of Exeter
TR10 9FE
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