[mapserver-users] Arc symbol.

Seth G sethg at geographika.co.uk
Wed Mar 6 06:18:02 PST 2019


Hi Marek,

I had a similar question last year - http://osgeo-org.1560.x6.nabble.com/Curves-in-MapServer-td5377180.html

You can add/draw CIRCULARSTRING geometries to MapServer using OGR - see the sample rainbow image at https://github.com/geographika/mappyfile-colors

The sample map file is: https://raw.githubusercontent.com/geographika/mappyfile-colors/master/example.map
This loads the following curved arcs from https://github.com/geographika/mappyfile-colors/blob/master/curves.csv

CONNECTIONTYPE OGR has to be used rather than using inline features as this approach defaults to using GEOS which doesn't support curves, whereas as forcing OGR does. 

Seth

--
web:http://geographika.co.uk
twitter: @geographika


On Wed, Mar 6, 2019, at 12:31 AM, Lime, Steve D (MNIT) wrote:
> Not within MapServer directly, at least not at first glance. There are circle layers but there’s no way to limit drawing to just a specific arc on that circle. Here are some other ideas:

> 

> 1) Perhaps it could be done externally in OGR or PostGIS and then rendered in MapServer as a polygon or a line…

> 2) You could also take a look at using javascript geotransformations:  https://mapserver.org/mapfile/geomtransform.html#javascript-transformation Support was added a while back and isn’t widely used but this is the sort of thing it was added for. In theory you should be able to compute the arc yourself and return it for rendering. So you pass in the 2 lines and then return the arc as a line shape or a pie slice as a polygon shape. (maybe this helps… https://stackoverflow.com/questions/45009327/draw-arc-between-two-lines-i-need-to-calculate-points)

> 

> If option 2 works this would be a great thing to archive – a library of geomtranforms. I might tinker with this tonight… ;-)

> 

> --Steve

> 

> *From:* mapserver-users [mailto:mapserver-users-bounces at lists.osgeo.org] *On Behalf Of *Marek Bak
> *Sent:* Tuesday, March 05, 2019 1:27 PM
> *To:* mapserver-users at lists.osgeo.org
> *Subject:* [mapserver-users] Arc symbol.

> 

> Hello All,

> Is it possible to create an arc symbol im mapserver? For example I have two lines constructed over some angle (ex. 30 degree) and I want to draw an arc between them.

> Regards,

> Marek

> 

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