Tiger Maps...

[Stephen Woodbridge]

Prasad,

I am CCing the mapserver list. They have lots of people that can help
you with questions related to that.

I assume you have looked at http://imaptools.com/tiger/

The concepts around vector maps is similar but different than raster
maps. In the URL above I am serving 18 GBs of tiger data covering the
whole US and the maps are about 32 KB for each map view which will
perform well even on dialup lines.

I have the data organized by state and county like

/u/data/tiger/data/state/county/shapefiles
/u/data/tiger/tileindexes

I use a tileindex to pull all the files together into layers
In the mapfile you need to set minscale and maxscale so an appropriate
level of detail is displayed at the various zoom scales you are working
with.

I'm sure other will have more advice for you if you ask.

-Steve W.

Anantha Prasad wrote:
> Hello Stephen:
> We (US Forest Service) are in the process of developing a MapServer
> application that seeks to get  coordinate input of Emerald Ash Borer (EAB)
> pest infestations from the general public. I was looking at your tiger map
> applications and realized that I am doing something similar and had a few
> questions, if I may take the liberty.
>
>  I have developed an application (using PHP Mapscript) that displays DOQQ
> and DRG images for quads in Ohio (the map file is changed on-the-fly based
> on which quad the user clicks, thus loading DOQQ and DRG files for only
> that quad). However, we realized that even this is too much for
> non-broadband users (and many folks in rural Ohio do not have broadband).
> So we wanted to develop an alternate application for dial-up users that
> uses Tiger 2000 Road/Rail/Hydro/KeyGeographicLocation shapefiles for
> identification purposes.
>
> Now my question is, since Tiger files are county based, it would still be
> too large if I were to load all county data when the user is just
> interested in seeing the roads in a particular quad (the scale at which EAB
> infestations can be identified) . I see in your application that the roads
> are displayed only when the user zooms in enough. However, my understanding
> (pls. correct me if I am wrong) is that the maps are loaded even though you
> have a MINSCALE/MAXSCALE associated with the layer - only that it
> "displays" within the scale-range. How do I minimize bandwidth requirements
> for dialup users (ie., not load the county maps until they have zoomed
> enough)? Will MINSCALE/MAXSCALE achieve this or should I be looking at
> cookie-cutting the Tiger county data to quads (which is fraught with
> problems since the application is going to be Ohio-wide). Is there any
> other way?
>
> Any suggestions or help would be greatly appreciated and acknowledged.
> Thanks much in advance.
> Best regards,
> Prasad
>
> *****************************************************************
> Anantha Prasad, Ecologist/GIS Specialist
> USDA Forest Service, Northeastern Research Station
> 359 Main Rd., Delaware OHIO 43015    USA
> Ph: 740-368-0103  Email: aprasad at fs.fed.us
> Web: http://www.fs.fed.us/ne/delaware/4153/4153.html
> Don't Miss Climate Change Tree Atlas at:
> http://www.fs.fed.us/ne/delaware/atlas/index.html
> ******************************************************************
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