[Imports] Questions about importing data for University of Vermont campus

[Frederik Ramm]

Hi,

On 01/28/11 21:25, Andrew Guertin wrote:
> Our most likely choice for this (mostly at my urging) is
> OpenLayers with an OpenStreetMap base layer. To do this, we need to get
> the data into the OpenStreetMap database.

No. You can do it, and for some data (especially such as partially 
exists in OSM already) it will likely make sense, but there are other 
possibilities to mix your data with OSM's:

a) Keep a local OSM database and a parallel database with you data; 
enhance Mapnik rendering rules to fetch data from both databases and mix 
them; create your own tiles.

b) Keep your own local database, write a Mapnik style sheet (or other 
rendering tech e.g. Mapserver, Geoserver) to create transparent overlay 
tiles with your information; make OpenLayers display OSM base tiles and 
your overlay on top.

c) Keep your own local database or KML files, write Javascript code to 
display your vector data on top of OSM base tiles in OpenLayers.

I'm not saying any of these is best, just pointing out that you are not 
forced to put your data into OSM.

> For an initial import,
> can we blow away the buildings and sidewalks and replace them with our
> own?

If you are sure yours are better, you might do that, however I would 
always contact the local mappers first before you "blow away" their hard 
work.

> Would any sort of automated process be acceptable, considering that our
> data would be both authoritative and accurate?

No. OSM does not have, and does not like, the concept of authoritative 
data. If you believe that your building data is authoritative, then you 
must choose option (a) above, simply omitting OSM buildings from your 
map tiles and drawing in yours instead.

> Or would we have to watch
> for when our data changed and make changes to OSM manually?

That you could do, however if such watching would mean a knee-jerk 
revert of anything a mapper does to a building that you consider 
"authoritative" then that's a bad idea.

Consider that it is not unlikely for enthusiast mappers to survey 
changes to the building landscape before they are in your 
"authoritative" database, and that such surveying work is at the core of 
the OpenStreetMap project.

> How can we watch for changes other users make to the data?
> I've found
> http://wiki.openstreetmap.org/wiki/OWL_%28OpenStreetMap_Watch_List%29
> and the rss feeds you can get from there. Is that the best way?

If you're savvy you can also process the minutely diffs from 
planet.openstreetmap.org directly but OWL is certainly easiest. If you 
render your own tiles then you will probably be processing the diffs one 
way or another anyway.

> What are our options in the case someone adds valid data that we don't
> want displayed on our base map tiles?
> For example, suppose someone adds every single emergency phone
> (http://wiki.openstreetmap.org/wiki/Tag:emergency%3Dphone) on campus to
> OSM (there are a lot), but we'd prefer to have that data in an overlay
> on our map so it can be turned on and off. Would we be forced to render
> our own tiles?

Yep. Interfering with OSM's data quality just so you can have it your 
way would not be acceptable to the community. However rendering your own 
tiles is really not such a big deal. It might even give you that extra 
bit of control against vandalism if you so desire; you could roll out a 
new set of tiles once a week after a cursory manual check or so. I'm not 
suggesting this is great (OSM likes minutely updates!) but you might be 
asked what your anti-vandalism mechanisms are and then you can say that 
this is possible.

Bye
Frederik