Importing OSM Data into PostGIS - Part 1

The PV Viability Map project seems to really be picking up some steam!  Thanks to our good fortune in having David Winslow join us, we now have someone with the skills and experience to move us forward -- thanks, David!  In our meet up last Thursday we had a first discussion of the requirements for the project, which I'll do my best to summarize here.

PV Viability Map Requirements

• Display map in web page.
• Search an address and display the building there.
• Standard map mouse navigation (drag to pan, mouse wheel to zoom, etc.)
• Click on building to identify.

I have been tasked with seeing how far I can get before next Thursday's meet up with the first task - displaying a map in a web page.  Actually, I've been tasked with the first part of this process - getting OpenStreetMap (OSM) data, trimming for Arlington, and loading it into PostGIS.

Process Overview

Before diving into looking for a solution, a pause to consider the process is in order.  From the Wikipedia page for OpenStreetMap we learn:

1. The main copy of the OSM data is stored in OSM's main database. The main database is a PostgreSQL database, which has one table for each data primitive, with individual objects stored as rows. All edits happen in this database, and all other formats are created from it.
2. For data transfer, several database dumps are created, which are available for download. The complete dump is called planet.osm. These dumps exist in two formats, one using XML and one using the Protocol Buffer Binary Format (PBF).

From what I can gather (and the notes I took at our last Code for NoVA meet up), I will be using a combination of two tools to grab the data from OSM's server and then push it into my local database:

1. osmosis
2. imposm

I was able to install both of those with:

$ sudo aptitude install osmosis imposm

I'm not clear when one would use imposm and when one would use osm2psql, which seems to be for the same purpose. I installed the latter as well with:

$ sudo aptitude install osm2psql

To be honest, I find the OSM wiki documentation to be very challenging to read. It appears thorough and is well written, but it assumes a wealth of background I lack.  Hopefully with time I'll be able to make better use of it.  For now I'll wait for our meet up this evening to see if David can help me figure out how to use osmosis to get data for Arlington County.