request for new mapserver features
Steve.Lime at DNR.STATE.MN.US
Wed Apr 26 12:17:15 EDT 2006
You can actually draw arcs already as a result of the modifications I made last summer to
allow the creation of pie charts. I have to dig around my brain for an example. You also
can use SIZE and SIZEUNITS to control the radius of a circle symbol. So we're most of
the way there. What's missing is the start angle. I was thinking about that back with charting
work (all charts start at 0 and pies are built from there).
Lemme check on the arc piece to see how close we are and get back to you.
>>> "Peter Freimuth (MapMedia GmbH)" <pf at MAPMEDIA.DE> 4/26/2006 3:18:24 AM >>>
Steve Lime schrieb: Could you post an image or two showing the output you are looking for?Steve "Peter Freimuth (MapMedia GmbH)" <pf at MAPMEDIA.DE> 4/24/2006 4:24:48 AM >>> Dear mapserver-dev Team,in context of using mapserver to generate a digital nautical mapchart out of s57 data (imported into postgres/postgis), we found two missing features to solve this task. Both features can be useful in a lot of other areas.- new feature type ARC, defined by:STARTANGLE in Degree (west=0/360, north = 90 ,east=180,south=270)ENDANGLE in degrees or ARCANGLE (negative value means clockwise direction) in degreesRADIUS (meter, miles or whatever)The feature can be used in the same manner as every other line or polygon feature. GD supports drawing of arcs so it should be not a big problem to introduce the parameters in the mapfileparser and to handle this featuretype inside of the current drawing routines.- draw a symbol at the center of polygons or lines (it is possible for labels so why not using the label offset point for symbol placement in the same way); it is possible to solve this inside of PostGIS, but i think it would also be a nice function for other datasources.Thanks for your interest and any feedback to this!Kind regardsPeter
Dear Steve and Mapserver-Dev Team,
This image shows the main problem we have at the moment. The arcs with different colors that are drawn between the lines coming from the same circle center used to define the arc itself. There is also one area with a symbol (red triangles) on line signature which would be possible if we activate the code which we allready send to steve which enables us to draw symbols inside or outside of polygon boundaries.- I understand the points mentioned by Frank in regard to WKT, shapeObj and reprojecting. If we want to handle these objects like standard geo objects, we have to convert them into simple feature objects inside of postgis or with the help of the converter (franks fantastic ogr s57 reader/writer lib in this case)On the other hand we are speaking about a "MAP" Server, which main task is to produce good looking maps for the web. So if you look at the arc feature from the mapping aspect there should be a possibility to support such features. In this context of nautical maps charts, the projection is always the same and will not change. Even if we have to reproject this object (because somebody makes the software to do this), we only have the reprojected arc center (center of the circle, where the arc is just a clipped part), the unchanged distance and the angles (both params cannot be handled by projection libs). Its the same for the lines that limits the arc on the left and right. They are defined by an angle and the length if I understood it correctly. So the problem is inside of the data definition and makes it impossible for any software to handle this in an other way as mapserver might do- I will have a look at the bug mentioned by Steve W. The main problem is, that I do not have a clear Idea of how to implement it (especially how the user interface should look like). I thought about a symbol section inside of the Label objekt (which breaks the object structure) or to use introduce a signalword inside of the symbol object which is used by the drawing function to identify the meaning of this symbol (pattern, line style or symbol at center. If somebody cann support me to find a logical and clear solution for an interface I would be pleased to implement a first patch for testing.Kind regards,Peter-- Mit freundlichem GrußPeter Freimuth_________________________________________________MapMedia GmbHKartographie und raumbezogene InformationssystemeHeilbronner Straße 10D-10711 Berlin Charlottenburgfon: +49.(0)30.89 06 82 70fax: +49.(0)30.89 06 82 73mail: pf at mapmedia.denet: www.mapmedia.depgp: on demand_________________________________________________
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