In this paper, we present the first algorithm to geometrically register multiple projectors in a view-independent manner (i.e. wallpapered) on a common type of curved surface, vertically extruded surface, using an uncalibrated camera without attaching any obtrusive markers to the display screen. Further, it can also tolerate large non-linear geometric distortions in the projectors as is common when mounting short throw lenses to allow a compact set-up. Our registration achieves sub-pixel accuracy on a large number of different vertically extruded surfaces and the image correction to achieve this registration can be run in real time on the GPU. This simple markerless registration has the potential to have a large impact on easy set-up and maintenance of large curved multi-projector displays, common for visualization, edutainment, training and simulation applications.

We present a system that superimposes multiple projections onto an object of arbitrary shape and color to produce high resolution appearance changes. Our system produces appearances at an improved resolution compared to prior works and can change appearances at near interactive rates. Three main components are central to our system. First, the problem of computing compensation images is formulated as a constrained optimization which yields high-resolution appearances. Second, decomposition of the target appearance into base and scale images enables fast swapping of appearances on the object by requiring the constrained optimization to be computed only once per object. Finally, to make high quality appearance edits practical, an elliptical Gaussian is used to model projector pixels and their interaction between projectors. To the best of our knowledge, we build the first system that achieves high resolution and high quality appearance edits using multiple superimposed projectors on complex non-planar colored objects. We demonstrate several appearance edits including specular lighting, subsurface scattering, inter-reflections, and color, texture, and geometry changes on objects with different shapes and colors.

In this paper we present a novel technique to calibrate multiple casually aligned projectors on a fiducial-free cylindrical curved surface using a single camera. We impose two priors to the cylindrical display: (a) cylinder is a vertically extruded surface; and (b) the aspect ratio of the rectangle formed by the four corners of the screen is known. Using these priors, we can estimate the display's 3D surface geometry and camera extrinsic parameters using a single image without any explicit display to camera correspondences. Using the estimated camera and display properties, we design a novel deterministic algorithm to recover the intrinsic and extrinsic parameters of each projector using a single projected pattern seen by the camera which is then used to register the images on the display from any arbitrary viewpoint making it appropriate for virtual reality systems. Finally, our method can be extended easily to handle sharp corners -making it suitable for the common CAVE like VR setup. To the best of our knowledge, this is the first method that can achieve accurate geometric auto-calibration of multiple projectors on a cylindrical display without performing an extensive stereo reconstruction.

Abstract. A color transfer function describes the relationship between the input and the output colors of a device. Computing this function is difficult when devices do not follow traditionally coveted properties like channel independency or color constancy, as is the case with most commodity capture and display devices (like projectors, camerass and printers). In this paper we present a novel representation for the color transfer function of any device, using higher-dimensional Bézier patches, that does not rely on any restrictive assumptions and hence can handle devices that do not behave in an ideal manner. Using this representation and a novel reparametrization technique, we design a color transformation method that is more accurate and free of local artifacts compared to existing color transformation methods. We demonstrate this method's generality by using it for color management on a variety of input and output devices. Our method shows significant improvement in the appearance of seamlessness when used in the particularly demanding application of color matching across multi-projector displays or multi-camera systems. Finally we demonstrate that our color transformation method can be performed efficiently using a real-time GPU implementation.

Multi-projector displays show significant spatial variation in 3D color gamut due to variation in the chromaticity gamuts across the projectors, vignetting effect of each projector and also overlap across adjacent projectors. In this paper we present a new constrained gamut morphing algorithm that removes all these variations and results in true color seamlessness across tiled multiprojector displays. Our color morphing algorithm adjusts the intensities of light from each pixel of each projector precisely to achieve a smooth morphing from one projector's gamut to the other's through the overlap region. This morphing is achieved by imposing precise constraints on the perceptual difference between the gamuts of two adjacent pixels. In addition, our gamut morphing assures a C1 continuity yielding visually pleasing appearance across the entire display.We demonstrate our method successfully on a planar and a curved display using both low and high-end projectors. Our approach is completely scalable, efficient and automatic. We also demonstrate the real-time performance of our image correction algorithm on GPUs for interactive applications. To the best of our knowledge, this is the first work that presents a scalable method with a strong foundation in perception and realizes, for the first time, a truly seamless display where the number of projectors cannot be deciphered.