A self-correcting projector

2012 Second International Conference on 3D Imaging, Modeling, Processing, Visualization & Transmission, 2012

Structured-light systems are simple and effective tools to acquire 3D models. Built with off-the-shelf components, a data projector and a camera, they are easy to deploy and compare in precision with expensive laser scanners. But such a high precision is only possible if camera and projector are both accurately calibrated. Robust calibration methods are well established for cameras but, while cameras and projectors can both be described with the same mathematical model, it is not clear how to adapt these methods to projectors. In consequence, many of the proposed projector calibration techniques make use of a simplified model, neglecting lens distortion, resulting in loss of precision. In this paper, we present a novel method to estimate the image coordinates of 3D points in the projector image plane. The method relies on an uncalibrated camera and makes use of local homographies to reach sub-pixel precision. As a result, any camera model can be used to describe the projector, including the extended pinhole model with radial and tangential distortion coefficients, or even those with more complex lens distortion models.

Computer Vision and Pattern …, 2009

In this paper we address the problem of geometric cal-ibration of video projectors. Like in most previous meth-ods we also use a camera that observes the projection on a planar surface. Contrary to those previous methods, we neither require the camera to be calibrated nor the pres- ...

Computer Graphics Forum, 2008

This article report focuses on real-time image correction techniques that enable projector-camera systems to display images onto screens that are not optimized for projections, such as geometrically complex, colored and textured surfaces. It reviews hardware accelerated methods like pixel-precise geometric warping, radiometric compensation, multi-focal projection, and the correction of general light modulation effects. Online and offline calibration as well as invisible coding methods are explained. Novel attempts in super-resolution, high dynamic range and high-speed projection are discussed. These techniques open a variety of new applications for projection displays. Some of them will also be presented in this report.

We describe a new steerable projector, whose projection center precisely corresponds with its rotation center, which we call a "fixed-center pan-tilt (FC-PT) projector." This mechanism allows it be set more easily to display graphics precisely on the planes in the environment than for other steerable projectors; wherever we would like to draw graphics, all we have to do are locate the FC-PT projector in the environment, and directing it to the corners of the planes whose 2D sizes have been measured. Moreover, by describing multiple planes in the environment by an integrated 2D coordinate system, it can display even a graphic that lies across a boundary line of two planes in a similar way to a paper poster folded along the planes.

2002

Abstract We describe a calibration and rendering technique for a projector array that can render a seamless rectangular image on a planar surface. The projectors utilize an attached camera to automatically compute the relative pose among them. We describe calibration of the full system using planar display surface to achieve registration and intensity blending of overlapping images. We present an efficient rendering method to pre-warp images so that they appear correctly on the screen, and show experimental results.

2005

Advances in display and input technologies have led to growing desire for creating a more immersive visual experience in interactive display systems. Research on constructing a large-scale, high-resolution display environment based on multi-projector mosaic has also become increasingly important to meet the costeffective consideration. In our previous work, we had developed a system called i-m-Top, which integrated one steerable fovea projector for high-resolution projection and another fixed wideangle projector for low-resolution. The touch-sensing is on the basis of diffused illumination and analyzed by computer vision approach. In this paper, we propose a fast, low-cost method for automatic projector calibration with the assistance of one color camera, to eliminate both the keystone effect and misalignment of the projections. Structured light patterns are projected to construct the geometric relationship between projectors and the projection surface, and then pre-warp the images ...

2011 IEEE International Conference on Multimedia and Expo, 2011

This paper proposes convenient and useful approaches to automatically calibrate the projectors of a multi-resolution display. The proposed approaches estimate both the keystone effect and misalignment of the projections with an assistance of a color camera. Structured light patterns are employed to construct the geometric relationship between projectors and the projection surface, and then pre-warp the images so that they appear undistorted as a result. Experimental results demonstrate that the proposed approaches successfully reduce the human-effort and lower the calibration time of multi-resolution display calibration task.

The accuracy of 3-D reconstructions depends substantially on the accuracy of active vision system calibration. In this work, the problem of video projector calibration is solved by inverting the standard camera calibration work flow. The calibration procedure requires a single camera, which does not need to be calibrated and which is used as the sensor whether projected dots and calibration pattern landmarks, such as the checkerboard corners, coincide. The method iteratively adjusts the projected dots to coincide with the landmarks and the final coordinates are used as inputs to a camera calibration method. The otherwise slow iterative adjustment is accelerated by estimating a plane homography between the detected landmarks and the projected dots, which makes the calibration method fast.

ACM Transactions on Graphics, 2003

Projectors are currently undergoing a transformation as they evolve from static output devices to portable, environment-aware, communicating systems. An enhanced projector can determine and respond to the geometry of the display surface, and can be used in an ad-hoc cluster to create a self-configuring display. Information display is such a prevailing part of everyday life that new and more flexible ways to present data are likely to have significant impact. This paper examines geometrical issues for enhanced projectors, relating to customized projection for different shapes of display surface, object augmentation, and co-operation between multiple units. We introduce a new technique for adaptive projection on nonplanar surfaces using conformal texture mapping. We describe object augmentation with a hand-held projector, including interaction techniques. We describe the concept of a display created by an ad-hoc cluster of heterogeneous enhanced projectors, with a new global alignment scheme, and new parametric image transfer methods for quadric surfaces, to make a seamless projection. The work is illustrated by several prototypes and applications.

2017 IEEE Conference on Computer Vision and Pattern Recognition (CVPR), 2017

We present a novel method that allows for simultaneous geometric and radiometric calibration of a projectorcamera pair. It is simple and does not require specialized hardware. We prewarp and align a specially designed projection pattern onto a printed pattern of different colorimetric properties. After capturing the patterns in several orientations, we perform geometric calibration by estimating the corner locations of the two patterns in different color channels. We perform radiometric calibration of the projector by using the information contained inside the projected squares. We show that our method performs on par with current approaches that all require separate geometric and radiometric calibration, while being more efficient and user friendly.