Opened 17 years ago

Last modified 13 years ago

#2221 closed defect

Bad 'angle follow' case -- possibly a use for splining — at Version 1

Reported by: crschmidt Owned by: sdlime
Priority: high Milestone: 6.0 release
Component: MapServer C Library Version: svn-trunk (development)
Severity: normal Keywords:
Cc: aboudreault, dmorissette, tbonfort, woodbri, jmckenna

Description (last modified by hobu)

http://boston.freemap.in/bugs/2221/poor_follow.png Uses:

http://boston.freemap.in/bugs/2221/poor-follow.map

All data in:

http://boston.freemap.in/bugs/2221/

Command used:

shp2img -m poor-follow.map -o poor_follow.png -e 232376.94043 900487.441406 232524.42627 900634.927246 -l roads_3_1

Discussion on IRC:

20:24:28 < hobu> Someone needs to do some splining
20:24:29 < crschmidt> Should I bother to file it as a bug?
20:25:06 < hobu> You could file an enhancement for 5.2 that says, 'we should improve ANGLE FOLLOW to support simple interpolation methods like splining for degenerative cases"
20:25:24 < hobu> It's way too big to be dealt with in the throws of our 5.0 release right now though
20:25:40 < crschmidt> understood
20:25:46 < crschmidt> Just wasn't sure if it was worth filing at all
20:26:19 < hobu> Another thing about the splining is we could maybe take advantage of it for feature rendering as well
20:26:38 < hobu> something those paleogeographers do from time to time ;)
<crschmidt>	what is that?
<crschmidt>	straightening out of too-curvy borders?
<hobu>	smoothen disjointed ones. They add map noise for very little information
* crschmidt	nods
<crschmidt>	something like what a simplification algorithm would do
<crschmidt>	only automatic/built into the rendering?
<hobu>	right, except not one that has to preserve topological relationships
<hobu>	http://en.wikipedia.org/wiki/B-spline
<hobu>	Would be a simple approach
<hobu>	Maybe you'd tell the mapserver renderer, 'hey, use 6-8 consequtive vertices to calculate your splines, if the incident angle is less than x degrees"
<hobu>	or something like that ;)
<hobu>	It'd be spendy, for sure
<hobu>	and not very useful for Manhattan grid systems :)

Change History (1)

comment:1 by hobu, 17 years ago

Description: modified (diff)
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