If you're wondering where the posts are this week, I've been busy at the AGU conference in San Francisco. Some brief notes on things I saw there:

Volcano Lesson Plan: Declan De Paor showed me a neat trick for use in a lesson plan teaching volcano hazards. Similar to my own lesson plan on volcanoes he uses Google Earth to explain volcano hazards in the vicinity of Mt Rainer. However, he gets students to work out a plan for evacuating the area and then challenges them with an eruption and gives them a limited time to work out what to do. To simulate the real situation he has students open a KML file which has a network link. At a given moment he changes a single file on a server (very simple text change), which triggers a 3D model of an ash plume to appear on Mt Rainer on each of the students' screens. A lovely way to make a simulation more effective.

User Testing: I'm planning some work to look at how effective Google Earth visualizations actually are in helping students with spatial learning. I was pleased to hear that I'm not the only one interested in this, Declan is using a program know as Sliverlight on the Mac to record how students use his materials in an effort to assess the effectiveness of Google Earth based educational materials. As I've been telling anyone who will listen here this week, user testing is the acid test of whether materials based in Google Earth work so great to hear Declan and his team are doing this too.

Produce a Photo 'Placard' in Google Earth

The idea is to produce a Placemark that has a small photo as an icon. When clicked it opens a full sized version of the image. The photo appears above the ground tethered to it by a line making it look like a placard.

Screen Shot from Stefan's original Kom Firin Post, the first example I saw of placards.
I think the weird green color is shading added by Google to make this part of the Nile delta look green at altitude. It works a mile up but from down on the ground it looks very odd.

Before we start you should find an image to use and produce a smaller version of it. This can either be a cropped image, a reduction in pixel size or a completely new small image like a company icon.

Lets dive in:

• Click the Yellow pin icon on the top of the 3D screen to produce a placemark.
• A yellow box appears in the main screen, drag it to where you want the placemark to sit.
  
• In the new placemark dialog box select the 'Altitude' tab and give the placemark an appropriate altitude above the ground and tick the 'Extend to ground' box. The extend functionality adds the handle to the placard.
  
• Click the yellow pin icon top right of the dialogue box, the 'Icon' dialogue will open. Click 'Add Custom Icon' button bottom left and locate your small image. Click OK
  
• Back in the main dialogue, click the description tab and add the text:

<img src="">

• Add your large image name and path inbetween the inverted commas. This is actually html code, if you're not used to it or get stuck this is a useful guide (scroll down in the link to find the section on adding images).
• Click the OK button and you're done!