[mapserver-dev] Request for review/comments on RFC 85 (Contour Layer Rendering)

[Stephen Woodbridge]

On 9/20/2012 2:21 PM, thomas bonfort wrote:
> On Thu, Sep 20, 2012 at 7:11 PM, Frank Warmerdam <warmerdam at pobox.com> wrote:
>> Alan,
>>
>> This looks cool, and I like the nice general way of specifying
>> different intervals at different scales.
>>
>> I'm mildly concerned that GDALContourGenerate is really producing more
>> detailed vector information than is likely necessary if you are
>> running it on elevation raster data at the map display resolution.
>> It will produce lots of basically one pixel vectors which need to be
>> styled.
>
> Frank,
> By that do you mean that the generated vector features will all be
> roughly one pixel long, or that the points inside a generated line
> will be roughly one pixel away from each other?
> In the first case, this would be a major problem, as it will be
> impossible to generate labels that follow a contour line. In the
> second case, the vector renderers won't slow down noticeably on line
> data that is sampled like this.

In the second case do the contour lines all become pixel stair steps? if 
this is the case, I would thing some smooth of the line speed things up 
a little and for labeling I would think it would generate smoother 
labels, but maybe not.

-Steve W

> --
> thomas
>> I'm not sure what the fix for that is.  One thing that might
>> help would be supporting a downsampling factor where the elevation
>> data would actually be loaded at a somewhat lower resolution than the
>> displayed map and generate the contours from that.
>>
>> In any event, assuming the performance is adequate it will work fine
>> as is, and exactly how the contours are produced could be changed in
>> the future.
>>
>> It is sweet to see my contour generator getting more use!
>>
>> Best regards,
>> Frank
>>
>>
>> On Thu, Sep 20, 2012 at 8:40 AM, Alan Boudreault
>> <aboudreault at mapgears.com> wrote:
>>> Hi devs,
>>>
>>> I'd like to request some review on a pending RFC regarding support for
>>> contour layer rendering.
>>>
>>> Please see
>>> https://raw.github.com/mapserver/docs/master/en/development/rfc/ms-rfc-85.txt
>>>
>>> The official rfc page should be updated in about a hour.
>>>
>>> http://mapserver.org/trunk/development/rfc/ms-rfc-85.html.
>>>
>>> Thanks,
>>> Alan
>>> --
>>> Alan Boudreault
>>> http://www.mapgears.com/
>>> _______________________________________________
>>> mapserver-dev mailing list
>>> mapserver-dev at lists.osgeo.org
>>> http://lists.osgeo.org/mailman/listinfo/mapserver-dev
>>
>>
>>
>> --
>> ---------------------------------------+--------------------------------------
>> I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
>> light and sound - activate the windows | http://pobox.com/~warmerdam
>> and watch the world go round - Rush    | Geospatial Software Developer
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