[mapserver-dev] Development of new functions "combine symbols" and "displace symbols"

Tue Jan 25 07:34:51 EST 2011

  Hello Thomas,

i hoped the labelcache code could be modified for the displacement. I 
understand the differences between the actual rendering procedure and 
the modified rendering (collecting the objects, calculate their relative 
position and render a virtual point).
I can talk with our customer about the time limit, perhaps it is not so 
critical an can be extended to March or April.

Greetings
Olaf

********************************************
Die WhereGroup ist umgezogen ...

Seit dem 01.01.2011 lautet unsere neue Adresse:

WhereGroup GmbH&  Co. KG
Eifelstraße 7
53119 Bonn

Alle Telefonnummern und eMail-Adressen
bleiben unverändert.
********************************************
-----------------------------------
WhereGroup GmbH&  Co. KG
Eifelstraße 7
53119 Bonn
Germany

Olaf Knopp
Geschäftsführer

Fon: +49 (0)228 / 90 90 38 - 27
Fax: +49 (0)228 / 90 90 38 - 11

info at wheregroup.com
www.wheregroup.com
Amtsgericht Bonn, HRA 6788
-----------------------------------
Komplementärin:
WhereGroup Verwaltungs GmbH
vertreten durch:
Olaf Knopp, Peter Stamm
-----------------------------------

Am 25.01.11 11:54, schrieb thomas bonfort:
> Olaf,
> as Tamas stated, I think the use case targeted here is compelling, and
> this would be a nice addition to mapserver.
> I'll speak for the rendering side of the propositions, as I'm not
> familiar enough with the featureinfo side of mapserver.
>
> * both propositions require a non trivial rework of the rendering
> pipeline, as feature would have to be accumulated, processed and then
> renderered, instead of the way that is currently done which is to
> render them as they arrive from the data source.
> * we can probably leverage the startLayer/endLayer calls, to trigger
> the fact that features should not be rendered directly, but be
> accumulated and rendered in a second phase.
> * the clustering strategy would be non trivial, are there any known
> algorithms or libraries that we could leverage?
> * for the displacement, we might be able to leverage the actual
> labelcache drawing code,  and only have to add the possibility of
> trying several locations for the label's symbol if the first one is
> already occupied by a previous symbol.
> * the end-of-february limit seems very ambitious, given the need for
> an RFC, the quantity of work to accomplish and the feature-freeze of
> the end of january.
>
> best regards,
> thomas
>
> On Tue, Jan 25, 2011 at 10:56, Olaf Knopp<olaf.knopp at wheregroup.com>  wrote:
>> Hi Tamas,
>>
>> thanks for you reply. Please check my answers below:
>>
>> Combine Symbols:
>> 1. I would prefer a centroid.
>> 2. I think it should be possible to click on the combined symbol and get a
>> featureInfo of all combined objects. Perhaps this is not useful if you have
>> many symbols. What do you think?
>> 3. For the moment we only need point layers.
>>
>> Displace Symbols:
>> 1. It should be possible to configure each layer (PRIORITY, DISTANCE of the
>> relocation and a displace ANGLE) to avoid the relocated symbols cover each
>> other.
>> 2. Yes this is a problem. I think we can't solve it, because it could create
>> a "cascade" in the mapfile with every symbol relocated. Perhaps we should
>> limit the function only to objects with the same coordinates. You will then
>> have to configure the mapfile and layers to provide the best map design.
>> 3. This could be a nice option. Perhaps with something like "ARROW YES/NO"
>> and a line symbol configured for the arrow. For our project it is not
>> necessary.
>> 4. For the moment we only need point layers.
>>
>> values of COMBINEUNITS and DISPLACEUNITS?: I think it would be best to use
>> the options that are mostly availible in MapServer:
>> [pixels|feet|inches|kilometers|meters|miles|nauticalmiles], but to make the
>> configurement easy pixels is the option of choice, because you can "play"
>> with symbolsize and the displacedistance.
>>
>> By the way. Do you know how this would work? Do we have to give a concept to
>> the steering commitee e.g. for the options like "COMBINEUNITS,
>> DISPLACEUNITS, COMBINESYMBOLS" etc? Do you commit to the MapServer trunk?
>>
>> Greetings
>> Olaf
>>
>> ********************************************
>> Die WhereGroup ist umgezogen ...
>>
>> Seit dem 01.01.2011 lautet unsere neue Adresse:
>>
>> WhereGroup GmbH&  Co. KG
>> Eifelstraße 7
>> 53119 Bonn
>>
>> Alle Telefonnummern und eMail-Adressen
>> bleiben unverändert.
>> ********************************************
>> -----------------------------------
>> WhereGroup GmbH&  Co. KG
>> Eifelstraße 7
>> 53119 Bonn
>> Germany
>>
>> Olaf Knopp
>> Geschäftsführer
>>
>> Fon: +49 (0)228 / 90 90 38 - 27
>> Fax: +49 (0)228 / 90 90 38 - 11
>>
>> info at wheregroup.com
>> www.wheregroup.com
>> Amtsgericht Bonn, HRA 6788
>> -----------------------------------
>> Komplementärin:
>> WhereGroup Verwaltungs GmbH
>> vertreten durch:
>> Olaf Knopp, Peter Stamm
>> -----------------------------------
>>
>> Am 24.01.11 23:12, schrieb Tamas Szekeres:
>>
>> Hi Olaf,
>>
>> The idea looks compelling to me, however I would have some further questions
>> before trying to propose a reasonable approach to this feature:
>>
>> Combine Symbols:
>> 1. What would be the position of the combined feature? Would this be one of
>> the features have been combined or some other location (like the centroid of
>> the features)?
>> 2. What did you mean by 'not to lose the FeatureInfo'? Does it mean that the
>> invidual features should be retrieved from a 'query by point option' and not
>> the combined feature?
>> 3. Would this option affect only the point layers (with marker symbols) or
>> some other types as well? (like annotations)
>>
>> Displace Symbols:
>> 1. How the position of the relocated symbols should be calculated? Would
>> this be a constant vector assigned to each layer/class?
>> 2. What should be happened when a relocated symbols would overlap with some
>> other symbols because of the relocation?
>> 3. Shouldn't the relocation be displayed somehow? (ie. by using a line or
>> arrow along with the symbol)
>> 4. What type of layers would be affected? (points only?)
>>
>> Assuming the distance threshold is specified in screen coordinates, what
>> would be the possible values of COMBINEUNITS and DISPLACEUNITS?
>>
>>
>> Best regards,
>>
>> Tamas
>>
>>
>>
>>
>> 2011/1/24 Olaf Knopp<olaf.knopp at wheregroup.com>
>>>   Hello everybody,
>>>
>>> for a project we need some software development to be done. We think these
>>> new features will become more important to provide modern and elegant maps
>>> and therefore would be a great add-on for MapServer. As working titles we
>>> call these functions "combine symbols" and "displace symbols".
>>> Here follows a rough concept for the functions.
>>>
>>> 1. Combine symbols
>>> This function combines symbols of the same layer (or class) to one symbol
>>> containing the number of combined symbols if viewed in a certain scale.
>>> For this you have to mark a layer/class e.g. by "COMBINESYMBOLS TRUE",
>>> give a distance between the symbols (COMBINEDISTANCE xy, COMBINEUNITS …),
>>> perhaps a MAXCOUNT etc. You will also have to define a symbol and the label
>>> for the combination. It would be best no to lose the FeatureInfo and get a
>>> list of templates after clicking on the combined symbol. You will find a
>>> nice example of combined symbols here: http://www.verbeterdebuurt.nl/ (zoom
>>> to the Netherlands).
>>> By configuring a zoom range (e.g. COMBINEMAXSCALEDENOM,
>>> COMBINEMINSCALEDENOM) you define in which scales the symbols should be
>>> combined.
>>>
>>> 2. Displace Symbols
>>> This function should relocate symbols of objects with same or similar
>>> coordinates so they don't conceal each other or overlap.
>>> For this you have to mark the mapfile e.g. by "DISPLACESYMBOLS YES" and
>>> give a distance between symbols that should be displaced (DISPLACEDISTANCE
>>> xy, DISPLACEUNITS …). Then you have to configure every layer similar to a
>>> label by giving a priority, a displace distance and an displace angle.
>>> You will also have to give a zoom range similar to the combine function
>>> described above. FeatureInfo should still work by clicking on the moved
>>> symbols.
>>>
>>> Who can develop this functions until the end of February? Is there anybody
>>> else interested in these functions?
>>> Please conctact us to discuss further details and to calculate a proposal.
>>>
>>> Greetings
>>> Olaf Knopp
>>>
>>> --
>>> ********************************************
>>> Die WhereGroup ist umgezogen ...
>>>
>>> Seit dem 01.01.2011 lautet unsere neue Adresse:
>>>
>>> WhereGroup GmbH&    Co. KG
>>> Eifelstraße 7
>>> 53119 Bonn
>>>
>>> Alle Telefonnummern und eMail-Adressen
>>> bleiben unverändert.
>>> ********************************************
>>> -----------------------------------
>>> WhereGroup GmbH&    Co. KG
>>> Eifelstraße 7
>>> 53119 Bonn
>>> Germany
>>>
>>> Olaf Knopp
>>> Geschäftsführer
>>>
>>> Fon: +49 (0)228 / 90 90 38 - 27
>>> Fax: +49 (0)228 / 90 90 38 - 11
>>>
>>> info at wheregroup.com
>>> www.wheregroup.com
>>> Amtsgericht Bonn, HRA 6788
>>> -----------------------------------
>>> Komplementärin:
>>> WhereGroup Verwaltungs GmbH
>>> vertreten durch:
>>> Olaf Knopp, Peter Stamm
>>> -----------------------------------
>>>
>>> _______________________________________________
>>> mapserver-dev mailing list
>>> mapserver-dev at lists.osgeo.org
>>> http://lists.osgeo.org/mailman/listinfo/mapserver-dev
>>
>> _______________________________________________
>> mapserver-dev mailing list
>> mapserver-dev at lists.osgeo.org
>> http://lists.osgeo.org/mailman/listinfo/mapserver-dev
>>
>>