Starting today, astronomy enthusiasts can now view imagery of millions
of celestial objects online - without downloading software.

Google Sky brings the imagery and functionality of the popular Sky in
Google Earth feature to a web browser, making it easier than ever for
students, amateur astronomers and professionals alike to explore the
universe.

By simply pointing their browsers to http://sky.google.com, users can
browse, zoom and pan the sky, search for stars and galaxies, and link
to any place in the sky. The same layers that are available in Sky in
Google Earth, such as “Backyard Astronomy,” “Hubble Showcase” and
podcasts from the radio program Earth & Sky can be accessed by
clicking on an image strip that appears along the bottom of the page.

For instance, the part of the sky visible when a user first loads
sky.google.com shows the Cigar Galaxy (also known as Messier 82), one
of the most striking galaxies in the universe. Switching on the
infrared view of the sky using the “Spitzer Infrared Showcase” button
at the bottom of the screen will overlay images from NASA’s Spitzer
satellite and show how different the Cigar Galaxy appears in the
infrared. When the overlay is activated a slider will appear, letting
users move back and forth between infrared and optical light. To look
in more detail, users should zoom into the galaxy or enter its name in
the search box.

With Rails 2, calling to_json on an AR object just gives you a hash of field name/values. The new way is easier and more intuitive. However, in breaks our code in places where we use to_json to pass AR data into JavaScript.

The changes are straightforward. There were two ways we dealt with the intermediate “attributes” hash prior to Rails 2:

1. we used map/collect before calling to_json, i.e.: cities.collect{|c|c.attributes}.to_json
2. we dealt with ‘attributes’ in JavaScript, i.e., var marker=markers[i].attributes

Fixing it just means removing references to the ‘attributes’ and using the ActiveRecord instance directly.

Here are all the places changes need to be made:

• 3.8: var marker=markers[i].attributes to var marker=markers[i]
• 4.6: all instances of result.attributes to just result
• 4.15: var stores=<%=(@stores.collect {|s|s.attributes}).to_json%>; to var stores=<%=@stores.to_json%>;
• 5-12: remove the to_json method from class Tower
• 7-2: render :text=>cities.collect{|c|c.attributes}.to_json to render :text=>cities.to_json
• 7-5: render :text=>cities.collect{|c|c.attributes}.to_json to render :text=>cities.to_json
• 7.15: var points=<%=@towers.collect{|c|c.attributes}.to_json %>; to var points=<%=@towers.to_json %>;

Indeed. Some of this will be well known to our readers, however our newer mashup friends might find something here that is interesting. Enjoy.

Pamela also put together a great example page demonstrating the different instantiation options. Other links for the project:

• Packed source code (can source directly from this URL)
• Unpacked source code (use for reference)
• DragZoom project Root
• Documentation: examples and reference

We’ve talked and talked about adding forums to this site and decided against it. We already do all of the support we can by email and encourage anyone who has trouble with anything in the books to contact us that way. If the problem is common enough we’ll blog about it instead. We also think that for all it’s UI short comings, the official API group is still the number 1 source for great support in this community. We just don’t want to fracture that.

However, if one of you is enterprising enough to start up a successful forum we’ll endorse it here to all of our readers and RSS subscribers. How’s that for a compromise?

Take care and good luck with all your maps!

From the over 450+ entries received we have randomly selected four lucky winners. They are:

1. Ryan Irelan of Raleigh, NC, USA
2. Daniel Leong of London, UK
3. Mike Hodgson (location withheld)
4. Aran Donohue (location withheld)

We have contacted each of the winners via email to arrange delivery of their prize. Congratulations!

Well, we had a number of requests by email for an explanation of how to set this up with clickable markers, so here it is. First, I’ve made a new version of the demo, which now features the traditional infoWindow popups, triggered by either marker clicks or selection from the sidebar.

If you just want the source for the new version, it’s right here. There’s a brief discussion of the changes, below the jump. (more…)

1. Download the zip file, gmaps_rails_code.zip
2. Create your own empty Rails application (rails your_app_name)
3. Unzip gmaps_rails_code.zip in the root of your newly created application. When you unzip the file, you will see it contains five root directories: app, db, lib, public, standalone_scripts. You want these directories to overlay the directories of your own Rails application.
4. set up your config/database.yml as appropriate for your environment. Most people just use root/no password for their development environment.
5. in routes.rb, add a line to configure the home_url: map.home '', :controller => 'app', :action=>'index'
6. run rake db:migrate to load the schema.
7. In your config/environments/development.rb, add a line to specify your own Google Maps API key:
   GOOGLE_MAPS_KEY=’your-google-maps-api-key’
8. Start your rails server, and go to http://localhost:3000/app (or adjust if your server is on a different port). You should see a welcome page and links to all the chapter examples.

These steps will give you the code and an empty database. This is meant to set the stage for you work with the various examples in the book. You will need to run the various data imports (capitol city scaping, FCC structure import, TIGER/Line data processing, etc) per the instructions in the book to fully populate the database.

After following the steps here, the examples in chapters 2,3,9, and 10 should work immediately. The rest of the chapters require some amount of data (primarily the FCC towers data), so you will need to load that data for the examples to work.

Notes

The Google Maps key is the primary configuration setting you need to get started. There are some others you will need for later chapters, however. You can add these to config/environments/development.rb file as well:

TIGERLINE_DIR="/path/to/your/tigerline/data"
YAHOO_API_KEY="your_yahoo_api_key"
UK_POSTCODE_DIR="/path/to/your/uk/postcode/data" #the directory, not the file

Finally, note that the Ruby on Rails examples are live at http://book.earthcode.com.