Reflection transformation imaging on larger objects: an alternative method for virtual representation

The term Reflection Transformation Imaging has been originally used by Tom Malzbender of the HP Laboratories to describe an image-based method to acquire the reflectance properties of objects' surface. This technique, as other image-based relighting techniques, creates a 'special' image of the object which encodes a reflectance function per-pixel. These images are called Polynomial Texture Maps (PTMs) (Malzbender et al. 2001). PTMs are generated starting from a set of photos of the object of interest taken under controlled illumination. Thanks to the reflectance functions encoded in the PTMs it is possible to generate new images of the object under different lighting conditions. Due to the easiness and effectiveness of this method PTMs have been used in several applications in the field of Cultural Heritage in recent years. One of the main motivation to use PTMs to represent artifacts is that this kind of visualization allows the user to change interactively the effects of the illumination on the object's surface, and hence the exploration of the object is performed in a new interesting way.