Hi QuddusAli,
To implement 3D zoom in and out, you should control the Camera location and other properties. However, if you do not want to change the scene
and the objects, you could choose to use the transformations for 3D elements, like
ScaleTransform.
On the other hand, 3DTool for WPF may help you:
http://3dtools.codeplex.com/
Sincerely,
Bob Bao
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