The following code excerpt specifies an AxisAngleRotation3D as the Rotation property of a RotateTransform3D.
//Define a rotation
RotateTransform3D myRotateTransform = new RotateTransform3D(new AxisAngleRotation3D(new Vector3D(0, 1, 0), 1));
The following code excerpt applies an AxisAngleRotation3D to a GeometryModel3D.
<ModelVisual3D>
<ModelVisual3D.Content>
<GeometryModel3D Geometry="{StaticResource myTeapot}">
<GeometryModel3D.Material>
<DiffuseMaterial>
<DiffuseMaterial.Brush>
<SolidColorBrush Color="Blue" Opacity="1.0" />
</DiffuseMaterial.Brush>
</DiffuseMaterial>
</GeometryModel3D.Material>
<GeometryModel3D.Transform>
<RotateTransform3D>
<RotateTransform3D.Rotation>
<AxisAngleRotation3D x:Name="myAngleRotation" Axis="0,3,0" Angle="1" />
</RotateTransform3D.Rotation>
</RotateTransform3D>
</GeometryModel3D.Transform>
</GeometryModel3D>
</ModelVisual3D.Content>
</ModelVisual3D>