Abstract: A sensory substitution device for enabling a user to perceive 3D structure, and optionally colour, of the environment. Image and range data derived from the sensor assembly is mapped into a low resolution 2D array such that each element of the 2D array contains the distance of the sampled region from the sensor assembly, and optionally the predominate colour of the corresponding sampled region. To interpret the range, and optionally colour data, elements of the 2D array are converted to electrical signals with frequency and intensity determined by the colour and range of the associated array element respectively. Each signal is used to stimulate nerves in the skin via electro-tactile electrodes or vibro-tactile actuators. The tactile electrodes (or actuators) are arranged in a manner that enables the user to intuitively determine from which array element and corresponding image component the signal has originated. Different frequencies represent different colours.