Ah yes - good point. John: I'll wait for your reply to Jody before attempting to answer your other posts.
Michael On 25 March 2011 16:13, Jody Garnett <[email protected]> wrote: > Hi John > You are asking lots of good questions; can you email us the working code > examples as you figure things out. > But first I want to check if you *have* to do this. If you are just trying > for a visual you can get away with just drawing the answer you want. There > are some flags that the rendering engine calls to "decimate" the geometry as > they are read out of a shapefile; resulting in the correct visual appearance > for the screen. > You could experiment with calling this flag yourself, if you like as a quick > way to throw away some of your data in a consistent fashion. > Jody > > On Fri, Mar 25, 2011 at 8:26 AM, John Moore <[email protected]> wrote: >> >> At 09:37 PM 3/24/2011 +1100, Michael Bedward wrote: >> >> Hi John, >> >> > However, I don't know how to remove the coincident vertices. I am >> > working >> > with a FeatureCollection from a shapefile, and the coincident vertices >> > are >> > in polygons in separate features. Also, I think what I really need to do >> > is >> > remove lines segments (2 or more consecutive vertices) that are covered >> > by >> > line segments from a different feature. >> > >> > Is there a way to do that short of manually picking apart the geometries >> > and >> > doing some sort of spatial search? >> >> If the vertices are coincident or nearly so, in terms of proximity to >> other vertices or they fall on line segments belonging to other >> polygons, then you should be able to remove then with >> TopologyPreservingSimplifier. I tried to show that with the example I >> posted. >> >> This is the second issue related to simplifying with multiple geometries. >> It is related to, but distinct from the prior thread. >> >> Stated in non-GIS terms: >> >> I have two kinds of United States political boundaries: >> States: relatively large areas. Described by multiple polygons >> Counties: smaller areas. Each county is contained with a single state, >> and every state is completely filled with counties. >> >> On a map, I wish to show state boundaries in one color, and county >> boundaries in another color (and lower Z-order so state boundaries hide >> county boundaries where they are coincident). >> >> The data I currently have (US National Atlast shape files) meet these >> criteria. >> >> GOAL:, I need to simplify the features - I don't need the full precision >> of the data, and I need the number of lines to be reduced for storage and >> processing reasons. >> >> THE PROBLEM: >> >> If simplify counties independently from states,county boundary lines >> which were included (in a colinear fashion) in state boundary (and hence >> hidden by the state boundary layer) are now no longer colinear. Hence when >> then two are displayed together, they look bad. As per the previous thread, >> adjacent county boundaries also become non-colinear unless county geometries >> are combined. >> >> I don't know how to achieve this using the tools. >> >> I have illustrated thisi in character graphics below (using Fixedsys >> font): >> >> >> BEFORE: (outer boundary is state boundary) >> >> ...-------------------------------+ >> | | >> | County A | >> | \ >> | \ >> | __+ >> | | >> | +-+ | >> County C +---------/ |--------+ >> | | >> | County B / >> | / >> | --+ >> | / >> | / >> ...-----------------------------+ >> >> DESIRED AFTER: >> >> ...-------------------------------+ >> | | >> | County A | >> | | >> | | >> | | >> | | >> | | >> County C +---------------------+ >> | | >> | County B / >> | | >> | | >> | / >> | / >> ...-----------------------------+ >> >> RESULT OF SIMPLIFYING STATES AND COUNTIES INDEPENDENTLY (to illustrate >> that different lines, colinear, become not colinear when simplified >> separately) >> >> ...-------------------------------+ >> | | >> | County A | >> | \ >> | |\ >> | |/ >> | | >> | /\ | >> County C +---------------------+ >> | | >> | County B /| >> | \| >> | + >> | / >> | / >> ...-----------------------------+ >> >> Thanks >> >> John >> >> >> ------------------------------------------------------------------------------ >> Enable your software for Intel(R) Active Management Technology to meet the >> growing manageability and security demands of your customers. Businesses >> are taking advantage of Intel(R) vPro (TM) technology - will your software >> be a part of the solution? Download the Intel(R) Manageability Checker >> today! http://p.sf.net/sfu/intel-dev2devmar >> _______________________________________________ >> Geotools-gt2-users mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/geotools-gt2-users >> > > ------------------------------------------------------------------------------ Enable your software for Intel(R) Active Management Technology to meet the growing manageability and security demands of your customers. Businesses are taking advantage of Intel(R) vPro (TM) technology - will your software be a part of the solution? Download the Intel(R) Manageability Checker today! http://p.sf.net/sfu/intel-dev2devmar _______________________________________________ Geotools-gt2-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/geotools-gt2-users
