Multi-touch sensing surface for projection-based AR

Data di pubblicazione




Data di priorità



Politecnico di Milano


Department of Mechanical Engineering


CASCINI Gaetano - CARUSO Giandomenico - BECATTINI Niccolò - MOROSI Federico


Spatial, or Spatially, Augmented Reality (SAR) is a relatively new approach for representing computergenerated contents with high immersivity on the real environment. This is a technological variation of the Augmented Reality (AR) paradigms and it has been developed to overcomes technical and ergonomic drawback of Mixed Reality (MR) setups. In such systems, the augmentation of the physical space is realized by projecting graphical information directly onto the external surface of objects without any image planes in between. The use of a tracking system allows keeping the projection updated according to the position and the orientation of the physical object. The current invention can be applied in all those fields that require a fast and agile alteration of the external visible features of a physical prototype or that need to visualize non-realistic information spatially coherent with the same. The shape of tangible object, available with real or scaled dimensions according to the needs, is used as a target surface for the projection and therefore it needs to be manufactured with a neutral colour, uniform finishing and non-reflective material. The images, generated for each of the projector included in the system, are then rendered by the control unit according with (i) the silhouette of the prototype computed from its 3D digital model, (ii) the placement data coming from the tracking system, (iii) the relative positions of the projectors, if more than one are available, (iv) the rendering capability of the projectors in term of colour, brightness and resolution of the light beams, (v) the external properties of the prototype surfaces and (vi) the modifications applied by the user(s) on the digital contents.

Campo di applicazione

ICT technology


he system presented in this patent benefits from the functionality provided by a state-of-the-art technology to enable a novel tracking approach for the physical objects to be used in projection-based SAR. For this reason, the following described technological advantages are referred with respect to other tracking system commonly used in the same type of applications: • It is insensitive to direct manipulations of the physical prototype that can alter the silhouette of the same (as opposed to algorithms based on edges recognition); • It allows to track all the translations and rotations that can be applied on a planar surface (as opposed to turn tables or sensors embedded in the prototype itself); • It allows a quick installation and an easy calibration of the hardware which becomes easily transportable (as opposed to tracking systems based on optical, acoustic and magnetic sensors); • It allows to avoid the use of physical markers attached onto the external surface of the physical prototype which, although minimally, alter its silhouette (as opposed to tracking systems based on optical sensors based on reflective IR markers); • It allows to have neutral and monochromatic surfaces of the physical prototype, fundamental for the fidelity of the colours that are rendered by the light beams of the projectors (as opposed to algorithms based on the recognition of the surface textures); • It allows to integrate within the multi-touch sensing surface an interactive graphical user interface to apply any modifications on the projected digital contents.