Custom Map Layers

• You can add your own map elements to the geochat web interface. These are 'layers'
• Your custom 'layers' are added to a group - all members of a group can see that layer if they have access to the website
• Layers can be lines, areas, images or any other element Google Earth support for KML & KMZ
• You need to upload a KML file - or point to a KML file available on the web
• If you point to a KML on the web that changes often, it will update itself on geochat every so many minutes or whenever you force a refresh

Geochat can be used to coordinate a team by using a map-based interface on its web page.

On this map, you can see the members of groups, messages they send, and reply directly to conversation threads on location.

It is useful in these scenarios to have team resources or reference information displayed on the map alongside your team members.

For example, you could want to see hospitals with some information about their resources (how many beds, contact information, etc) Or, you could want to show administrative boundaries like neighborhood or vulnerability assessments.

In disaster situations, satellite imagery is continuously updated. You may want to overlay a KMZ with updated satellite pictures to see current terrain, debris, flood, smoke, etc. spreads.

To Add a custom layer: 1. Log in to geochat and go to the map view

2. On the top menu bar, find the 'Layers' menu. You will see layers you and others have added previously

3. Click on 'Add Layer' at the bottom of the menu

4. Select the file from your disk or point to it on the web¹⁾:

5. Choose a name and assign it to a group:

6. You can now show and hide it by selecting the checkbox next to the layer in the Layers menu:

• To refresh a Layer that is being displayed from another website, you can click on the green arrows to the right of the layer on its menu item
• To delete a Layer click on the trash can to its right, and confirm the Yes/No dialog.

Not all KMLs and KMZs that Google Earth shows can be displayed by Google Maps.

This is not a limitation of GeoChat, rather the constraints that Google places on its own tools in their current versions. You can read the restrictions Google places on KML display in Google Maps here: http://code.google.com/apis/kml/documentation/mapsSupport.html

Basically they place

• Restrictions on what sort of placemark and shape gets shown
• Restrictions on size of the KML being displayed

What can you do to avoid these problems?

Sometimes you have a KML/KMZ that won't display correctly. Here are some tips:

• If your KML doesn't show, it could be there is a portion of it that is causing problems, but the rest of the file is fine. Maybe you can isolate the troublemaking part of the document by:

1. Opening the KML / KMZ in Google Earth
2. Seeing the list/tree of parts that makes it up
3. Right-click on a sub-branch of the tree and click 'Save Place As..' and save it with a different name
4. Upload this new smaller file to test it

• Google Maps may decide to display some things differently than Google Earth
  • Some labels that are just visible in GE appear as dots in GM that you need to click to view, ruining the visual effect
  • 3d Shapes may be recolorized and flattened on the ground
  • Shapes that have visibility ranges (e.g. that appear and disappear according to the users' zoom level) will always be visible, maybe hiding other features
  • Shapes that have timelines associated will always be visible