[GRASS-user] BAnk and ditch symbols in grass (or other Open Source GIS)

GRASS GRASS user
1

Hi,

I am an archaeologist mainly working within woodlands and need to be be able to display in grass of similar GIS the location of woodland banks and their associated ditches. There is a standard set of symbols for this but is there a way of actually getting GRASS or other GIS to implement these.

If not has anyone any ideas on how to write the appropriate code or adapt other code to do it. My initial thoughts were to digitize the location of the features to a vector map. As a vector it has direction and therefore if a standard was adopted say for example if a ditch existed it was on the rhs of the vector and the dashes marking the bank could then be placed on the lhs.

Eventually the information about the profile of the bank and ditch needs to be analyzed statistically so having the information within a data base makes good sense.

Thanks

Tim
Dr Tim Southern
17, Park Close,
Sonning Common,
Oxfordshire.
RG4 9RY
0118 972 1197
0778 453 0776

2

Hi Tim,

Although it's definitely possible to make maps with GRASS, I personally
prefer to use GRASS to produce my data and then make my maps with QGIS.
Therefore I'm not too familiar with GRASS cartography (is definitely
possible) but QGIS makes it quite easy. You could create custom vector
symbology that does just what you describe and load your vectors into a
database (see QGIS User Guide, especially chapter 3.4, Vector Properties
Dialog -
http://download.osgeo.org/qgis/doc/manual/qgis-1.5.0_user_guide_en.pdf). I'm
not so sure about vectors with directions, though. You could categorize your
lines as having their left side in a certain direction, for example... Or
maybe somebody else has a better idea for that.

Best,
Daniel
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3

Tim wrote:

I am an archaeologist mainly working within woodlands and
need to be be able to display in grass of similar GIS the
location of woodland banks and their associated
ditches. There is a standard set of symbols for this

any online link to an image of what they look like?

but is there a way of actually getting GRASS or other GIS to
implement these.

are they point symbols or line styles?

point symbols:
  http://grass.osgeo.org/wiki/IconSymbols

line styles are more tricky, but I would not say impossible.

If not has anyone any ideas on how to write the appropriate
code or adapt other code to do it. My initial thoughts
were to digitize the location of the features to a vector
map.

e.g. the fish on the above wiki page was "digitized" from the
QGIS .svg symbol in Inkscape, then a little Bézier curve math
to make the x,y points,
  http://grass.osgeo.org/wiki/Symb-fish

the "classic" model for this is the CERL castle graphic for
d.graph (see d.graph/grass_logo.txt in the source code),
initially drawn on graph paper and then transfered.

As a vector it has direction and therefore if a
standard was adopted say for example if a ditch existed it
was on the rhs of the vector and the dashes marking the bank
could then be placed on the lhs.

so you mean like cliff polylines rendered by Mapnik for
OpenStreetMap: http://wiki.openstreetmap.org/wiki/Cliff

e.g.
http://www.openstreetmap.org/?lat=-44.1026&lon=-176.5281&zoom=13&layers=M

?

see also geology/strike_triangle:
  http://grass.osgeo.org/wiki/IconSymbols#New

grass vector lines have direction, so setting them as true-left
and right bank can be easily done. (see `d.vect display=dir`)

Eventually the information about the profile of the bank
and ditch needs to be analyzed statistically so having the
information within a data base makes good sense.

should be pretty easy if lines were as a vector map. a number
of tools exist for it.

regards,
Hamish