GRASS 6.0

Heads up digitizing with v.digit

screenshot: O. Dassau

Buffering with v.buffer

screenshot: R. Blazek

Overlapping polygons
Overlapping polygons input from Shapefile (or any other OGR simple feature format) screenshot: R. Blazek	Result (areas colored by number of overlapping areas, categories of layer 1 and 2) screenshot: R. Blazek

Example of import and use in GRASS

  # GRASS 6.0:
  v.in.ogr dsn=./shp/ layer=fire output=fire_p
  v.category input=fire_p output=fire_c type=centroid field=2
  echo "create table fire_c_2 (id int, num int)" | db.execute
  v.db.connect map=fire_c driver=pg database=bridge layer=2 table=fire_c_2 key=id
  v.to.db map=fire_c layer=2 option=cat col1=id
  v.to.db map=fire_c layer=2 qlayer=1 option=query col1=num qcol="count(*)" type=centroid

Number of overlapping features is also written as category to centroid.

Another example of overlapping features in one layer (overpass)

screenshot: R. Blazek

Vector overlay using v.overlay
Input A and B screenshot: R. Blazek
intersection (operator=and) screenshot: R. Blazek	union (operator=or) screenshot: R. Blazek
not (operator=not) screenshot: R. Blazek	exclusive or (operator=xor) screenshot: R. Blazek

Charting using d.vect.chart
Pie charts (default) screenshot: R. Blazek	Bar charts (ctype=bar) screenshot: R. Blazek

Network analysis
Shortest path using d.path screenshot: R. Blazek	Split network into bands using v.net.iso screenshot: R. Blazek	Allocate subnets using v.net.alloc screenshot: R. Blazek

GRASS 6.0

Overlapping polygons

Vector overlay using v.overlay

Charting using d.vect.chart

Network analysis