[Freegis-list] Ideas on best FOSS options

[John Zastrow]

Artem Pavlenko wrote:
>
> On 4 Feb 2008, at 02:01, John Zastrow wrote:
>
>> I need to create an attractive set of static tiles for the USA (based on
>> shapefiles) to populate a web-server-only (e.g., small-footprint, not
>> dynamic, not a real map server) online map to embed in a java-based
>> application without internet access.
>>
>> My first attempt used ArcGIS to render a GeoTIFF of a layout at high
>> resolution and then passed the image into gdal2tiles.py
>> (http://www.klokan.cz/projects/gdal2tiles/) (which is EXCELLENT) to
>> create a shell OpenLayers app that I can customize. This worked fine,
>> except the image quality from ArcGIS was horrible, particularly when
>> zoomed in (no anti-alias).
>
> I don't think your approach will work.  Even if you manage to create a 
> very large geotiff, re-sampling it to create low resolution tiles 
> would produced anything but nice looking maps. Also, for high zoom 
> levels the image size will blow your memory away. Creating good 
> cartography would most certainly require per zoom level styling.
>
>>
>> I'm a now trying to use mapnik (mapnik.org) to create the same image at
>> higher quality. But I am suffering deeply from an acute lack of
>> documentation which makes creating the cartography even more painful
>> (where are recipes, examples, and docs for mapnik?)
>
> Have a look at : 
> http://trac.openstreetmap.org/browser/applications/rendering/mapnik/generate_tiles.py 
> [1]
> This script generates tiles with all styles and data defined in : 
> http://trac.openstreetmap.org/browser/applications/rendering/mapnik/osm.xml 
>
>
>>
>> Is there something else that I can use to create the tiles needed for
>> the OpenLayers app?
>
> I suggest you read OpenLayers docs.
>
>> Or is there an easier tool for creating a high-res,
>> high-quality georeferenced image that can be used by gdal2tiles.py? Any
>> thoughts would be greatly appreciated.
>
> I'm not familiar with gdal2tiles.py but as I mentioned above, 
> re-sampling vector maps won't produce high-res, high-quality tiles 
> (assuming this is what you're trying to achieve).  You might try 
> creating two layers : chop your raster data with gdal2tiles.py and 
> create transparent overlay tiles using Mapnik. Also, Mapnik supports 
> gdal raster directly and you can generate high quality tiles with 
> raster and vector combined. see [1]
>
> HTH
> Artem
Ok, you lost me a little with your last note (I agree, I'd like to weave 
together at least two zoom levels into a static tile set). Are you 
saying that Mapnik can import the newly cut tiles and set transparency 
(perhaps based on a color)? Can you elaborate on what I would do with 
Mapnik's support for GDAL rasters? If [1] was a link it did not come 
through in the email.

Thanks.