[mapserver-users] Offset values from database

[Wim Vanbelle]

Maybe this pic helps elaborate on what i'm trying to accomplish:
http://fileshare.myroute.be/exchange/asymmetriclinedrawing.png
It should be noted that the distance between the 2 (new) lines, should be a
fixed value over the zoomlevels. It must not be the case that at the
furthest zoomlevel the lines are further apart.

I've looked all over for this, but never really found a proper solution. I
tried cartographic symbol drawing, but it only draws on the same side every
time. Maybe I'm just doing it wrong :).


On 12 August 2010 16:28, Wim Vanbelle <wimvanbelle at gmail.com> wrote:

> Hello,
>
> thanks for your feedback.
>
> The issue with this, is that the underlying linestrings (the 2 that would
> lie on top of eachother), have different colors :(.
>
> So they have to be moved apart from one another. I have not found a way to
> do this with asymmetric line drawing either, as it will always offset to the
> same side.
>
> This is why i would need the offset value to be configurable in the
> database. I could select a different pixel offset for each line and they
> would always appear next to eachtoher (no matter what zoomlevel).
>
> I can elaborate on the problem more if I am a little too confusing !
>
>
>
> On 12 August 2010 16:20, Cristiano Sumariva <sumariva at gmail.com> wrote:
>
>> If it is a display problem why not try create some special symbology to
>> overlap one line with another using different symbol strokes. So the user
>> will se that are 2 lines overlayed.
>>
>> 2010/8/12 Wim Vanbelle <wimvanbelle at gmail.com>
>>
>>> Hi David,
>>>
>>> I read that documentation before though. I was hoping it just hadn't been
>>> updated... Is this possibly a feature for 6.0 ?
>>>
>>> Are there any other ways how one could offset a feature in pixels, rather
>>> than in lat/long coords?
>>>
>>> Maybe I should elaborate on the original problem a little. Consider 2
>>> line segments that lie above one another. The general idea is to 'offset'
>>> them a given x , y value, so they will both display next to one another,
>>> rather than on top of eachother.
>>>
>>> If you would however perform this code simply on lat/long values, it
>>> would imply, that when scaling your map at the most detailed zoom level, the
>>> lines would lie very far apart, and when zoomed out, they would appear to
>>> lie on top of eachother.
>>>
>>> I find it hard to believe that I would need to pre calculate all the data
>>> in order to obtain geometry objects for each zoom level.
>>>
>>> Maybe some veterans have some good insight in this :).
>>>
>>>
>>> On 12 August 2010 15:26, Fawcett, David (MPCA) <
>>> David.Fawcett at state.mn.us> wrote:
>>>
>>>>  Wim,
>>>>
>>>>
>>>>
>>>> If you don’t want me to tell you, you will likely want to look at the
>>>> mapfile documentation at: http://mapserver.org/mapfile/style.html
>>>>
>>>>
>>>>
>>>> [Spoiler Alert]
>>>>
>>>> You can’t use values from an attribute table to set the value of this
>>>> property
>>>>
>>>> [/Spoiler Alert]
>>>>
>>>>
>>>>
>>>> David.
>>>>
>>>> *From:* mapserver-users-bounces at lists.osgeo.org [mailto:
>>>> mapserver-users-bounces at lists.osgeo.org] *On Behalf Of *Wim Vanbelle
>>>> *Sent:* Thursday, August 12, 2010 5:48 AM
>>>>
>>>> *To:* mapserver-users at lists.osgeo.org
>>>> *Subject:* [mapserver-users] Offset values from database
>>>>
>>>>
>>>>
>>>> Hi,
>>>>
>>>> I'm trying to load offset X, Y data from the postgis database.
>>>>
>>>> Each feature has an offset value defined there.
>>>>
>>>> My mapfile (relevant part) looks like this:
>>>>
>>>> In the layer:
>>>>                 DATA                    "geom_mercator from map_links
>>>> using unique Id using SRID=900913"
>>>>
>>>>                         STYLE
>>>>                                 WIDTH 6
>>>>                                 COLOR 0 255 0
>>>>                                 ANTIALIAS TRUE
>>>>                                 ANGLE AUTO
>>>>                                 OFFSET [offsetX] [offsetY]
>>>>                         END
>>>>
>>>> Please don't tell me the offsetX, Y values cannot be read from the
>>>> database. That would be a huge issue for me.
>>>>
>>>> Thank you for your time.
>>>>
>>>> Best regards
>>>>
>>>
>>>
>>> _______________________________________________
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>>>
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>>>
>>>
>>
>
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