AW: [mapserver-dev] RFC49:
mapfile simplifications andsymbologyenhancements
Daniel Morissette
dmorissette at mapgears.com
Tue Dec 9 13:48:40 EST 2008
Steve,
I agree that expressions like this would be really cool, but wouldn't
they be quite slow if applied to large number of shapes?
Daniel
Steve Lime wrote:
> I kinda like this approach since it would already be familiar to folks
> (I think Steve W. was lobbying for this back when I proposed the binding
> support. Would just have to document a couple
> of standard "recipes" for users.
>
> Steve
>
>>>> On 12/5/2008 at 9:43 AM, in message
> <49394C1D.5040108 at geoanalytic.com>, Brent
> Fraser <bfraser at geoanalytic.com> wrote:
>> Steve,
>>
>> Perhaps a compromise would be to allow some simple arithmetic
> expressions
>> (like the ones in the FILTER keyword?), such as:
>>
>> SIZE ( 18 + [poptotal] * (( 43-18)/(5000-30000)) )
>>
>> In my case, I've got ANGLEs in a shapefile (ok, 13,000 shapefiles) as
>
>> "standard" angles (0=x-axis, + is ccw) but Mapserver likes azimuths
>> (0=y-axis, + = cw). I'd rather not add another field to the
> shapefile, to
>> minimize the data management problems.
>>
>> Brent Fraser
>>
>>
>> Steve Lime wrote:
>>> MapServer's interpretation of size through an attribute binding is
>>> literal. That is, the value
>>> in the column is used as the size in pixels. Since you set a max
> scale
>>> it makes sense you
>>> see all size 43.
>>>
>>> In that case your suggestion makes sense although I'm not sure the
> best
>>> way to implement.
>>>
>>> I don't think strictly following the charting syntax makes sense
> since
>>> we'd then have two ways
>>> to bind attributes which would get confusing. Any ideas?
>>>
>>> Steve
>>>
>>>>>> "Karsten Hoffmann" <khoffmann at igf.uni-osnabrueck.de> 12/04/08
> 5:59
>>> AM >>>
>>> Hi Thomas,
>>>
>>> I’m not sure if I understand what you mean.
>>>
>>> I tried your proposition with Mapserver 5.2. But all circles have
> the
>>> same
>>> size (43 pixel):
>>>
>>> LAYER
>>> NAME population
>>> TYPE POINT
>>> STATUS default
>>> DATA Lan_point.shp
>>> CLASS
>>> NAME 'Population'
>>> STYLE
>>> SYMBOL 'circle'
>>> SIZE [poptotal]
>>> MINSIZE 18
>>> MAXSIZE 43
>>> OUTLINECOLOR 0 0 0
>>> COLOR 0 0 255
>>> END
>>> END
>>> END
>>>
>>> The sizes of the circles should vary depending on the number of
>>> habitants. I
>>> don’t want to preprocess the population data. At the moment I
> calculate
>>> the
>>> sizes of the circles by myself and write them in a new field
> (pop_size)
>>> in
>>> the attribute table.
>>> The Style is then:
>>>
>>> STYLE
>>> SYMBOL 'circle'
>>> SIZE [pop_size]
>>> OUTLINECOLOR 0 0 0
>>> COLOR 0 0 255
>>> END
>>>
>>> The population varies from around 5000 to 30000 habitants. The sizes
> of
>>> the
>>> circles should vary from 18 to 43.
>>>
>>> With a Chart-Layer it is very comfortable to define this:
>>>
>>> PROCESSING "CHART_SIZE_RANGE=poptotal 18 43 5000 30000"
>>>
>>> But I don’t want to have a pie chart with slices here just a
> simple
>>> filled
>>> circle.
>>>
>>> Best,
>>> Karsten
>>>
>>>
>>> -----Ursprüngliche Nachricht-----
>>> Von: thomas bonfort [mailto:thomas.bonfort at gmail.com]
>>> Gesendet: Donnerstag, 4. Dezember 2008 12:18
>>> An: Karsten Hoffmann
>>> Cc: mapserver-dev Mailing List
>>> Betreff: Re: [mapserver-dev] RFC49: mapfile simplifications and
>>> symbologyenhancements
>>>
>>> karsten, if I understant your request correctly, MapServer already
> has
>>> that:
>>>
>>> STYLE
>>> SYMBOL "circle"
>>> SIZE [population]
>>> MINSIZE 3
>>> MAXSIZE 20
>>> END
>>>
>>> you'll probably want to preprocess the [population] in your data
>>> request (to add steps, or scaling)
>>>
>>> regards,
>>> thomas
>>>
>>> On Thu, Dec 4, 2008 at 11:45, Karsten Hoffmann
>>> <khoffmann at igf.uni-osnabrueck.de> wrote:
>>>> Dear developers,
>>>>
>>>> I would like to ask for another feature which could be perhaps
>>> included in
>>>> this RFC.
>>>>
>>>> Since version 5.2 it's possible to bind the size of pie charts to
> an
>>>> attribute (https://trac.osgeo.org/mapserver/ticket/2136):
>>>> PROCESSING "CHART_SIZE_RANGE=itemname minsize maxsize minval
> maxval"
>>>> This would also be useful for point symbols as simple diagrams
> without
>>>> slices or bars. The idea is to have a symbol, let's say a filled
>>> circle or
>>>> square, which varies continuously in size. The size is bound to an
>>> attribute
>>>> for example the absolute number of habitants of different
> countries.
>>>> This would be a useful feature for thematic mapping. Is it possible
> to
>>>> implement this?
>>>>
>>>> Best regards
>>>> Karsten Hoffmann
>>>>
>>>>
>>>> -----Ursprüngliche Nachricht-----
>>>> Von: mapserver-dev-bounces at lists.osgeo.org
>>>> [mailto:mapserver-dev-bounces at lists.osgeo.org] Im Auftrag von
> thomas
>>> bonfort
>>>> Gesendet: Donnerstag, 4. Dezember 2008 11:18
>>>> An: mapserver-dev Mailing List
>>>> Betreff: [mapserver-dev] RFC49: mapfile simplifications and
>>>> symbologyenhancements
>>>>
>>>> Hi,
>>>>
>>>> Not sure if the changes warrant a full blown RFC, but as there
> quite a
>>>> number of them I've regrouped them.
>>>>
>>>>
> http://trac.osgeo.org/mapserver/browser/trunk/docs/development/rfc/ms-rfc-49
>
>>>> .txt
>>>>
>>>> These changes are/were all in RFC45, but were extracted to keep
> things
>>>> moving on as some of the stuff in rfc45 lacks funding in the near
>>>> future.
>>>>
>>>> You can see it in action here on openstreetmap data:
>>>> http://mapserverosm.s3.amazonaws.com/parisosm.html
>>>> nothing that's impossible to do with the current mapfile keywords
>>>>> greatly simplified, as e.g. roads are mostly defined with a
> single
>>>> class whatever the scale (using a combination of sizeunits at the
>>>> layer level, and min/max width and min/max scale at the style
> level)
>>>> regards,
>>>> thomas
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>>>>
>>>>
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--
Daniel Morissette
http://www.mapgears.com/
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