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Working With Avatars

An avatars is the visual representation of a user within a virtual space. Open Cobalt allows you to use any one of four different avatar types: Ogre Motion 3D avatars, non-motion 3D Avatars, 2D "Poster" avatars and an special invisible avatar type.

Switching Avatars

  1. Choose Cobalt > My Avatar...
  2. In the Choose Avatar window select one of the four tabs, depending on the type of Avatar you wish to select.
  3. In the right pane select Avatar file nameClick OK.
  4. The Enter scale factor dialog box automatically opens. Use it to size your object (you can also resize the object later using Cobalt's edit tools). By default the scale is set to 1, meaning the object will be imported at its originally created dimensions. You can the scale factor above 1 to increase the object's size or below 1 to decrease it.
  5. Click OK.

Creating a 2D Poster Avatar

You can make your own 2D Avatars based on photos or other images. The idea is to "knock" out the background of the image so that only the silhouette remains.

You'll need an image-editing program such as Photoshop or Gimp (free) that supports transparency.


  1. Create a new file in your image editor (make sure you've chosen to use a transparent background layer)
  2. Drag your image into the newly created file, adding it as a new layer on top of the background layer.
  3. Remove the background to define the silhouette. The simplest way to do this in an application like Photoshop is with the eraser tool. The magic wand tool works well if the background is comprised of a solid color. But if you have more advanced image-editing skills you may find a more efficient method. There should be a very small or better yet non-exsistent margin on the top and bottom of the silhouette. The height calculations scale the whole image to the standard height, if there are transparent margins the avatar will appear to be small and floating in the air.
  4. Export the image as a .png file.
  5. Copy the image into Cobalt's avatar images directory (content>avatars>images).

Here's an example:

Tip: Add a temporary layer, filled with a solid high contrast color, in between your transparent background layer and your image layer. This will help you better see the border of the silhouette as you remove the background. Before exporting the .png remember to remove the temporary layer.

Bear in mind...since the poster avatar is based on a 2D image there is no back side. Both you and others in the Cobalt space will always see the "front" of the image.

Avatar Descriptions and Properties

    Avatar Description Files

    The Open Cobalt avatar chooser lets you pick various kinds of graphical content for your avatar and will attempt to rescale it to the standard avatar sizes (see below).  Sometimes this procedure produces unwanted results, or you may have something unusual you want to try. You can override a number of the default parameters by creating an Avatar Description (.adst) file for the avatar and selecting this in the file chooser instead of the graphical file. The avatar description contains a reference to the graphical content and a number of other parameter specifications. See the avatar height section for an example for a billboard avatar. The system assumes file names that end in .adst are avatar descriptions.

    Avatar Heights:

    The default height and scale calculations assume that the avatar is 175 cm tall (a touch under 5'9"). For calculating the camera/eye height in first person it is assumed the avatar is 7 1/2 heads tall (Wikipedia on Body_proportions), which puts the eye height at 163 cm. You can override these height: and eyeHeight: settings in an avatar description file. For example, to make a billboard avatar with the the standard heights explicitly expressed, the file would contain:

    ^(TAvatarBillboardRepresentation new)
        source: 'MyAvatarImage.png' ;
        realHeight: 1.75 ;
        eyeHeight: 1.63 ;    

    This would then be saved in the same directory as the MyAvatarImage.png and named with a .adst extension. Linear dimensions in a .adst file are in meters.