[GRASS-dev] v.clean tool=prune - 'thresh' interpreted wrong?

[Maciej Sieczka]

There is a line:

	$ echo "L 4 1
	 10 10
	 20 10
	 30 10
	 40 10
	 1     1" | v.in.ascii -n out=line format=standard


So there are 4 vertices and the distance between each 2 following is
10. Then I don't understand why the:

	$ v.clean input=line output=line_pruned type=line tool=prune
	thresh=1

removes ALL the vertices!:

	$ v.out.ascii line_pruned format=standard
	ORGANIZATION:
	DIGIT DATE:
	DIGIT NAME:   shoofi
	MAP NAME:
	MAP DATE:     Mon Oct  2 20:51:52 2006
	MAP SCALE:    1
	OTHER INFO:
	ZONE:         0
	MAP THRESH:   0.000000
	VERTI:
	L  2 1
	 10           10
	 40           10	   <- WHY ARE THE TWO OTHER GONE ???
	 1     1


I declared thresh=1, the distance between vertices is 10 - so none
should be removed, but all are! And the same happens with all the lower
thresholds until thresh=0.03.

???

v.clean man says: "prune: remove vertices in threshold". Maybe I don't
understand what the threshold means in this case?

Maciek

P.S.

Any clarification will be highly appreciated. I've been writing a
script that uses pruning and I would like to publish it, but this is
puzzling me bad and I don't know whether it's a bug or my mistake. Thanks.