[R-sig-Geo] From spatial points to "spatial pictures"

Maurizio Marchi mauriziomarchi85 at gmail.com
Wed Aug 5 15:56:23 CEST 2015

Hi everybody,
I'm maurizio Marchi and I'm working as a post-doc at the Forestry Research
Centre of Arezzo (Italy) and I have a question concerning spatial points
During my research activities I have to collect data about the crown
projection on the ground of trees. The aim is to "measure" the crown area
and to draw a sort of picture on GIS software (QGIS in my case) to analyze
the area and the perimeter of the crowns compared to the "free area" of a
plot (generally a circular plot) to have an idea of how much photosynthetic
radiation is able to reach the soil. My working steps are:
1) During the survey on the field each crown of each tree is initially
"drawn" collecting 8 points that have to be connected to become a spatial

###---example of table to be processed
    1            1       x    y
    1            2       x    y
    1            3       x    y
    1            4       x    y
    1            5       x    y
    1            6       x    y
    1            7       x    y
    1            8       x    y
    2            1       x    y
    2            2       x    y
    2            3       x    y
    2            4       x    y
    2            5       x    y
    2            6       x    y
    2            7       x    y
    2            8       x    y
    N            8       x    y

2) the points,sorted by Tree become the vertices of the polygons

3) The polygons have to be processed to obtain a smoothed polygons,
circumscribing the polygonal crowns (e.g.

I generally do it on QGIS and GRASS but is there something more appropriate
on R to do this? for example with rgdal or sp package?

Many thanks

Maurizio Marchi
Calenzano (FI) - Italy
ID Skype: maurizioxyz
Ubuntu 14.04 LTS
linux user 552742

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