[mapserver-users] Railroad and dual carriage way styles

[Stephen Lime]

The problem with the old format was that the offset piece was just an approximation and fell apart in certain instances (like hairpin corners). Some simple rules were used to calculate the offset and this resulted in things like railroad tracks in which tracks were not perpendicular to the rail. In experimentation before I made the switch I found that I could create most every symbol with the new system that the old one supported. The only major deficiency was that truely hollow lines couldn't be supported. You can make parallel lines with space between them but you can't see stuff underlying the space. The new system allows for a wide variety of new symbols with more flexible color schemes that really does boost performance. For example, it used to be that to create a red centerline with a black outline took 2 layer defs (and 2 passes over the data). Now that is done in one pass. In addition you get things like fat polygon outlines. I'll try and post some samples over the weekend.

If we find a particular deficiency I would propose adding a couple of new line symbol types specifically to address them. I don't want to go back to offsets though.

Steve

Stephen Lime
Data & Applications Manager

Minnesota DNR
500 Lafayette Road
St. Paul, MN 55155
651-297-2937
>>> "Hockaday, John" <JohnHockaday at auslig.gov.au> 12/13/01 21:34 PM >>>
Steve,

This was a big help.  I managed to get some lines that look similar to the
original formats.  

I feel that the Mapserver 3.4 offset capability of the STYLE tag was much
easier to use, understand and looked better.  

Developers,

Are there any intentions to reintroduce the offset capability to the STYLE
tag?    Please, please, please say yes!!!  It's much easier to use!!!   ;--)

Thanks again to this list for a quick and accurate response.

John

> -----Original Message-----
> From:	Stephen Woodbridge [SMTP:woodbri at swoodbridge.com]
> Sent:	Friday, December 14, 2001 12:16 AM
> To:	Hockaday, John
> Cc:	'mapserver-users at lists.gis.umn.edu'
> Subject:	Re: [mapserver-users] Railroad and dual carriage way styles
> 
> 
> John,
> 
> I have had no answer to my query on railway symbols, but did come up
> with a idea for a good looking alternative based on a dual carriageway
> in 3.5.
> 
> dual carriageway:
> 
> SYMBOL 'circle'
> COLOR 0 0 0
> SIZE 5
> OVERLAYSYMBOL 'circle'
> OVERLAYCOLOR 255 0 0
> OVERLAYSIZE 3
> 
> railway:
> 
> SYMBOL 'circle'
> COLOR 0 0 0
> SIZE 5
> OVERLAYSYMBOL 'dcircle'
> OVERLAYCOLOR 255 255 255
> OVERLAYSIZE 3
> 
> where 'dcircle' is defined as:
> 
> SYMBOL
>   NAME 'dcircle'
>   TYPE ELLIPSE
>   FILLED TRUE
>   POINTS 1 1 END
>   STYLE 5 5 END
> END
> 
> The other idea I had was to do an overlay to generate --0--0--0--0--
> where the circles are filled, you could use "STYLE 1 5 END" above
> instead.
> 
> I hope this helps,
>   -Steve
> 
> "Hockaday, John" wrote:
> > 
> > Hi,
> > 
> > I noticed a while ago in the archives that some one wanted to know how
> to
> > make a railroad line in Mapserver 3.5 map files.  I couldn't find any
> > answers to that question so I am asking this one.
> > 
> > In Mapserver 3.4 one could generate a dual carriageway by way of
> offsets.
> > eg
> > 
> > STYLE
> >   -1 0 0
> >     1 0 0
> > END
> > 
> > but in Mapserver 3.5 it seems that the STYLE doesn't have offsets.
> > 
> > How do I generate a railway   "---|---" and how do I generate a dual
> > carriageway "==="?
> > 
> > Thanks in advance.
> > 
> > John