Display a map using Tiger data

[Ryan D Taylor]

Hi,

Just an update.  You were right about the extent info.  I put in the
output from ogrinfo -ro -so -al and it works beautifully.  Thank you so
much.

Ryan T.



On Tue, 19 Apr 2005, Frank Warmerdam wrote:

> On 4/19/05, ryan <ryant at cs.utah.edu> wrote:
> > Hi,
> >
> > I'm having trouble displaying a map of street data i got from the tiger LINE
> > project.  mapserv doesn't give me any errors, just shows a blank png.  I can
> > run the demo stuff fine.  I've also tried changing STATUS from ON to OFF to
> > DEFAULT in my mapfile.  Also, I don't know for sure what the extent of my
> > map should be, but i'm passing 1.00, 1.00, 50000.00, 50000.00 because i can
> > use arcexplorer on my windows machine to find that the dimensions of the map
> > are about 50Km by 50Km.
>
> Ryan,
>
> I would suggest the issue is extents related. Likely all your vectors are
> getting drawn in one pixel.  I would suggest you use some utility to get
> the extents of your dataset in their intrinsic coordinate system which would
> be lat/long if they are tiger/line data (that hasn't been reprojected).
>
> For shapefiles and a few other formats, you could use ogrinfo.
>
> eg.
>  ogrinfo -ro -so -al abc.shp
>
> > Here is the web address i access:
> > http://localhost/cgi-bin/mapserv?map=/usr/bin/apache/htdocs/mapserver/simple.map&mode=map&layer=Freeways&mapext=1.00%201.00%2050000.00%2050000.00&imgsize=300%20300
> >
> > And my map file is here:
> >
> > #-------start of map file---------------#
> > NAME sampleMapServer
> > # the below extents and size are provided in the URL and so must be removed
> > #EXTENT 482925.85 3625874.39 497393.16 3617143.43
>
> Note, just because you are listing the extents in the url doesn't
> mean you have to remove them from the map.  The info passed in
> the url just overrides the info in the map file.  I generally try to fill
> out reasonable information in the mapfile so I can use utilities like
> shp2img for debugging purposes.
>
> PS. there are lots of possible reasons your map could be failing to draw
> besides the extents issue, but it is pretty hard for us to remotely debug
> without all supporting files, and a clear understanding of what version
> of mapserver you are running.  Generally "mapserv -v" output is more
> useful than your configure line.
>
> 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
> and watch the world go round - Rush    | Geospatial Programmer for Rent
>
>