The dictionary key of the input range image whose 3D coordinate space tree holds the desired output space. In the case of input range / greyscale image pairs, this is the key of the nested container that in turn holds the range image whose 3D coordinate space tree holds the desired output space. The Execute  method will throw an ArgumentException if this dictionary key does not exist within the input CogVisionDataContainer.

When set to an empty string, this parameter is treated specially. An empty string is interpreted to mean that we will use an arbitrarily chosen input range image as the source of the output space. This may be usefull when the output space is defined in all input images.