A string identifier used to create a depth data based WebCamTexture.
This string is null for webcam devices that do not support depth data. For webcams with depth data support (those of kind WebCamKind.ColorAndDepth) this string is not empty. Currently, only dual back and true depth cameras on latest iOS devices support depth data.
Additional resources: WebCamDevice.kind, WebCamTexture.WebCamTexture.