Adenovirus virion, autostereogram. An example of stereoscopy (or stereo imaging), an autostereogram is designed to create the visual illusion of depth. The impression of a 3D scene is created due to binocular parallax, creating depth perception because of the different view from each eye. When viewed correctly, this image shows the external protein structure of an adenovirus virus particle. The capsid is icosahedral, having 20 triangular faces. Inside the capsid is the genetic material. Adenoviruses commonly cause infections of the upper respiratory tract and eyes.