I’ve been getting e-mail from people asking about the state of various locations in and around New Orleans and other areas hit by Hurricane Katrina. I’m not the best person to answer such questions — I’m just someone from small-town western Quebec who runs a site about maps; I haven’t even visited New Orleans — but I’ve tried to be as helpful as I can be.

Part of the problem is that matching up an address to a satellite photo isn’t always easy. Kathryn Cramer has a couple of tutorials here and here: you can use Google Earth if your computer is powerful enough and runs Windows (note to Google: hurry up with the Mac version already), or you can manually match the address to the appropriate post-Katrina photo.

Now there’s an easier way. I mentioned before that Google Earth overlays, both official and third-party, were available. Google’s been updating its Google Earth overlays on a daily basis since then, and now Google Maps has post-Katrina satellite photography too; here’s a direct link. Just enter the address and toggle between map, satellite, hybrid and Katrina modes to see what’s happened. Via Google Blog.

(For more on the use of Google Maps and Earth during this disaster, have a look at this Forbes article. Via All Points Blog.)

The other part of the problem is that not every location has been photographed; a few people have asked about areas that haven’t turned up on the new photos. It clearly takes time to assemble detailed satellite imagery, and some areas haven’t yet been looked at. (I’ll try to find out a few things about how satellite photography works — especially coverage and lag time — for a future post.)

All we can do is keep looking for new images when they crop up. Most of the web sites I’ve linked to over the past week are frantically adding new photos as they become available, so keep checking them.

Here’s another one to keep an eye on: NOAA has collected some very high-resolution satellite imagery of New Orleans; the interface is confusing but the photos are big.

In the meantime, I’ll report updates and new sites as I find out about them.