Creation of realistic natural texture-mapped 3-D objects is very tedious using conventional computer graphics techniques. The user normally constructs a 3-D shape of the object through a computer-aided design process and then the texture patches are selected by hand and mapped onto the object surface manually, piece by piece. Or, there are some systems which scan a subject using laser to obtain the range map as well as surface reflectance map of the subject, but these systems are very expensive and are intrusive to human and animal subjects, and they do not work for large objects, such as buildings, and fail on dark or specular surfaces. The real take-off of virtual reality (VR) in this age of multimedia requires a virtual reality builder that is easy to use, inexpensive, and gives realistic results. The Camera Aided Virtual Reality Builder (CAVRB) just needs a few images of the object to be modeled. It computes the 3-D shape of an object from these images using matched object points specified by the user through an intuitive, graphics-based user interface. The natural textures are then mapped on to the 3-D shape directly from those images. With the CAVRB, it is very convenient to build realistic VR scenes or objects from real objects, or to incorporate additional VR objects into VR scenes constructed using existing methods. Virtually any real-world object can be converted into a VR object using the CAVRB, such as human faces, human bodies, buildings, trees, gardens, cars, machine parts, geological terrains, interior of a room, furniture, etc.
Advantages include: (1) Easier to use. The system does not require the user to provide the 3-D shape of the object. (2) Lower in cost. The system uses images taken by commercially available CCD video or still cameras rather than an expensive computer aided design system or a laser scanner. Both of these require experts to run, and the laser scanners are limited in applicability. (3) Realistic result. The texture mapped directly from camera images gives human observers a very realistic impression because the ability of the human vision system to perceive 3-D shape and surface material from shading, specularity, texture, and texture variation. (4) The resulting VR object is truly navigable and compact in storage. Some technology requires multiple views for each hot spot (viewing position) and the user stitches these images into a panoramic screen for each hot spot. The observer can only view the object by jumping from one hot spot to next, but cannot view between any two hot spots or beyond. Such a hot-spot-based representation is redundant for those surface patches that are visible from more than one hot spot.