[NTLUG:Discuss] GPS Mapping Software

[Rick Cook]

On Monday 19 September 2005 23:38, Steve Baker wrote:
> Kyle Davenport wrote:
> > *** Authentication Certificate ***
> >
> > Rick Cook wrote:
> >>I am looking for a way to take the mapping information on the
> >>laptop and use it to create a detailed map
> >
> > wow, I've been looking for this too.  I assumed at this late stage of
> > the game there would be numerous free sources of maps and waypoints. 
> > Instead I find all the "rich" detail buried in proprietary and
> > expensive formats that the open-source community hasn't cracked yet. 
> > Geez, it reminds me of office software in 1995 [shudder].
>
> There is one source of clean, free, public mapping information that was
> gathered by the US goverment for census-taking purposes in 2000.  It
> hasn't been updated since - but one presumes it will be since it's
> required for census-taking.
>
> It's called 'TIGER':
>
>    http://www.census.gov/geo/www/tiger/tgrcd108/tgr108cd.html
>    http://arcdata.esri.com/data/tiger2000/tiger_download.cfm
>
> It's fully documented and as far as I can tell, it's fairly complete
> for things that were there in 2000.
>
> I've written crude programs to extract the road data for some small
> area and display them as vector data on a Linux PC.  You are welcome to
> copies of those if you think they'll help...but they aren't in a state
> where I'd say they were useful for much as-is.
>
> There is a lot of other data there too.
>
> However, it's not clear how you'd get it from the TIGER format into
> whatever format your GPS uses.
>


Precisely.

Roadmap uses the Tiger data to display detailed street information and 
some water features. It does a good job of zooming between levels of 
detail within the information, however, it only shows the street 
information in little pop-up bubbles. However, this does mean that 
Roadmap understands what each little line segment represents. You can 
download the mapping information for each state from the Roadmap site. If 
you already have access to the Tiger data (or use a Roadmap provided tool 
to download it), Roadmap also provides some utilities you can use to turn 
the raw data into Roadmap compatible info.

GPSdrive uses adifferent approach. It downloads map images of various 
resolutions from places like Expedia and tags each one with position and 
coverage information. This means that the maps are "prettier" than the 
Roadmap rendered ones, however, you only have the map resolutions you 
have downloaded and the little line segments are just part of the image.

I have not yet found a way to turn any of the information from either tool 
into something useful for installing on a GPS (let alone my relatively 
new version). There is a program called gpsbabel  that purorts to convert 
from lots of different GPS specific formats, however, you first have to 
have some type of GPS specific format.Gpsbabel also says it will 
interface with the Tiger online mapping service, however, I haven't quite 
figure that out yet - nor have I figured out if it would do me any good 
if I did...


Rick