global mapping issues with orthographic projection

[Sean Gillies]

On Apr 22, 2005, at 5:20 PM, Ken Tanaka wrote:

> We would like to use MapServer to generate continent and country/state
> outlines for satellite images. Currently we are looking for image
> overlays
> from MMS for Geostationary full disk and sub-areas.
>
> At the moment we are having some troubles with a "starburst" of stray
> feature lines that can be seen in this URL:
>
> http://gdsg.ngdc.noaa.gov/starburst/
>
> Our current approach is to generate the lines with MMS, and then use a
> separate step to merge the data (satellite image) with the outlines
> image,
> and produce the composite image seen in the above URL.
>
> I have seen a couple of references that look like they are describing
> this
> problem in
>
> http://mapserver.gis.umn.edu/cgi-bin/wiki.pl?WorldMappingIssues
>
> see "Linework:" near the bottom of the MapServerWiki page, and
>
> http://mapserver.gis.umn.edu/data2/wilma/mapserver-users/0401/
> msg00569.html
>
> Does anyone know of any recent work in this area, or hopefully of a new
> solution I haven't run accross yet?
>
> Thanks,
> Ken Tanaka
>
>

Ken,

Starburst aside, it looks like your states aren't properly overlaid on
the GOES imagery.  Have you actually processed the vectors into an
orthographic projection?  If not, you should set the layer projections
to (I assume, after looking at your map image) a latlong projection.
After doing that, let's see if the starburst problem remains.  It may
... see the image at the bottom of

    http://zcologia.com/news/16

for an example of failure to properly deal with a graticule for an
orthographic projection.

cheers,
Sean


--
Sean Gillies
sgillies at frii dot com
http://users.frii.com/sgillies