Changes between Version 2 and Version 3 of UsersWikiSimplifyPreserveTopology

Timestamp:

Apr 8, 2012, 6:33:00 AM (12 years ago)

Author:

nicolasribotosgeo

Comment:

—

UsersWikiSimplifyPreserveTopology

@@ -3 +3 @@
 == What we want ==
 
-Simplifying this layer:
-
- [[Image(SPT_dept_ori.png)]] 
-
-into this: 
-
- [[Image(SPT_dept_sim.png)]] 
+|| Simplifying this layer: || into this: ||
+|| [[Image(SPT_dept_ori.png)]] ||  [[Image(SPT_dept_sim.png)]] ||
 
 == The data ==
@@ -25 +20 @@
 == Principle of simplification ==
 
-Based on the technique described here [[]], we extract linestrings out of polygons, then union and simplify them.
-st_polygonize() is used to rebuild surfaces from linestrings. Attributes from the initial layer are associated with simplified polygons.
+Based on the technique described here [[]]:
+* we extract linestrings out of polygons, 
+* then union and simplify them
+* st_polygonize() is used to rebuild surfaces from linestrings. 
+* Finally, attributes from the initial layer are associated with simplified polygons.
 
 == Steps ==
@@ -98 +96 @@
  [[Image(SPT_bad_attributes.png)]] 
 
-8. Second method is based on percentage of overlaping area comparison. It gives better results in our testcase.
+8. Second method is based on percentage of overlaping area comparison.
 {{{
 create table simpledep as (
@@ -107 +105 @@
 );
 }}}
+
+ It gives better results in our testcase:
+
+ [[Image(SPT_good_attributes.png)]] 
+
 
 9. rebuild departements by grouping them by code_dept (other attributes could be re-associated here):