[GRASS-user] Question about v.generalize: nothing is removed when using douglas_reduction?

[hardinej]

Hi,
I'm trying to use v.generalize method=douglas_reduction, but the output has
the same number of vertices as the input map and I don't know why it is not
being simplified.

In case it helps, the input map is:
v.info JR_2001SubSetLines

+----------------------------------------------------------------------------+
 | Layer:           JR_2001SubSetLines                                       
|
 | Mapset:          generalize                                               
|
 | Location:        3DInterp                                                 
|
 | Database:        /home/eric                                               
|
 | Title:                                                                    
|
 | Map scale:       1:1                                                      
|
 | Map format:      native                                                   
|
 | Name of creator: eric                                                     
|
 | Organization:                                                             
|
 | Source date:     Tue Jun  9 16:12:20 2009                                 
|

|----------------------------------------------------------------------------|
 |   Type of Map:  vector (level: 2)                                         
|
 |                                                                           
|
 |   Number of points:       0               Number of areas:      0         
|
 |   Number of lines:        11758           Number of islands:    0         
|
 |   Number of boundaries:   0               Number of faces:      0         
|
 |   Number of centroids:    0               Number of kernels:    0         
|
 |                                                                           
|
 |   Map is 3D:              Yes                                             
|
 |   Number of dblinks:      0                                               
|
 |                                                                           
|
 |         Projection: Lambert Conformal Conic                               
|
 |               N:        251271.999    S:        250940.025                
|
 |               E:        913711.894    W:        913272.031                
|
 |               B:            -1.288    T:            14.218                
|
 |                                                                           
|
 |   Digitization threshold: 0                                               
|
 |   Comments:                                                               
|
 |                                                                           
|

+----------------------------------------------------------------------------+
when I run 
v.generalize input=JR_2001SubSetLines output=JR_2001_SSL_reduc_50
method=douglas_reduction threshold=0 reduction=50 type=line --o
I get
Number of nodes: 11758
Number of primitives: 11758
Number of points: 0
Number of lines: 11758
Number of boundaries: 0
Number of centroids: 0
Number of areas: 0
Number of isles: 0
Number of vertices was reduced from 23516 to 23516 [100%]

Adding the -r flag to remove small lines gives the same result.
Using method=douglas without the -r flag gives the same result.
Using method=douglas with the -r flag works, but I would like to know what
I'm doing wrong and how to use the reduction feature.
Thanks,
Eric



-----
Eric Hardin
-- 
View this message in context: http://n2.nabble.com/Question-about-v.generalize%3A-nothing-is-removed-when-using--douglas_reduction--tp3068397p3068397.html
Sent from the Grass - Users mailing list archive at Nabble.com.