[mapserver-users] Just starting out...

Roger André randre at gmail.com
Mon Nov 10 14:21:17 EST 2008


Hi Tucker,

My experience using the techniques that Frank's described below ("burn" away
areas of non-interest using gdal_rasterize, then layer separate raster
layers in Mapserver) has been very good.  The one additional piece that I
have used is TileCache, so that I can generate PNG tiles for display in
Google Maps.  Of especially great value to me has been Mapserver's ability
to display data sets together which often differ in their projections.

One thing I would advise you to do first is to display 2 different data sets
that overlap, in 2 different projections, in a simple mapfile.  Then check
that the reprojection is working properly and that features line up.

Sounds like a neat project,

Roger
--


On Mon, Nov 10, 2008 at 10:50 AM, Frank Warmerdam <warmerdam at pobox.com>wrote:

> tuckeratwork wrote:
>
>>    What information do you have now defining the regions for the
>>    cutouts?  Are
>>    you expecting to need to manually define polygons for these by
>>    digitizing?
>>  First, wow - I'm getting answers from the source!  I'm sorry to bother
>> you with such trivial questions.
>>
>
> Tucker,
>
> The questions are not at all trivial, though possibly hard to give
> solid answers for.
>
>  Yes, I expect to write a quick digitizing program to define the boundaries
>> and cutouts.  There's some other meta data I need to collect too.  The
>> borders aren't in the header like the BSB/KAP files.
>>  I'll definitely check out the gdal_rasterize utility - that's the exact
>> kind of advice I was looking for.  I'm a developer and don't mind writing
>> custom code if needed with gdal, etc.
>>
>
> The utility is available as part of GDAL and is documented at:
>
>  http://www.gdal.org/gdal_rasterize.html
>
> Note the -i flag to invert the sense of what is inside or outside.
>
>  How about the quilting aspects of it all?  Will I get the type of tile
>> results that GeoGarage got?  I'm not really sure how they did what they did
>> - perhaps they used MapServer too...
>>
>
> MapServer should be able to quilt images fairly well if you can burn away
> all the stuff you don't want to show, and then order them as you want them
> layered.  If the images are not all in the same coordinate system you may
> need to use multiple LAYER's for them otherwise you can just dump them into
> a tileindex (ie. shapefile) with some care to ordering.
>
> When burning away uninteresting parts of the images make sure you burn them
> out to a particular value that can be used as the OFFSITE value in your
> LAYER definition - assuming you don't go the alpha transparency route which
> is somewhat involved.
>
> What you want to do should be achievable but may be somewhat challenging.
> I'm not sure that it is critical to do it through mapserver.  You could
> likely achieve something similar by creating a suitable mosaic image, and
> gdalwarp'ing the individual maps into that in a suitable order (after
> appropriate masking).
>
> Best regards,
> --
>
> ---------------------------------------+--------------------------------------
> I set the clouds in motion - turn up   | Frank Warmerdam,
> warmerdam at pobox.com
> light and sound - activate the windows | http://pobox.com/~warmerdam<http://pobox.com/%7Ewarmerdam>
> and watch the world go round - Rush    | Geospatial Programmer for Rent
>
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