Key Technology Research And Application On Geometric Calibrating And Color Correction Of Multi-projector Display

Multi-projector display system Multi projector display system is widely used in the field such as Museum exhibition,simulation training,and interactive exhibitions.The display screen is made up of a number of single projection images,in order to achieve the visual effect of seamless splicing,calibration of geometric distortions and color distortion is necessary.Existing geometric calibration technologies have been able to solve accuracy problem of calibrating geometric distortions,but professional initialization work is still needed because the complete continuous online adaptive calibration has not yet been achieved,which severely limits the widespread use of multi-projection display systems.The existing color correction technology has been able to solve the color distortion caused by projection on different texture surface and photometric inconsistency problem caused by the projection area overlap or projector individual differences.But in surround environment projection,light inter-reflection resulting in irradiation and color deviation,how to maintain a high display quality in those environment is still a challenging work.In this thesis we describe and comparative analysis the related research work of adaptive geometric calibration method,projection color compensation method considering the integration of the environmental impact and so on,and then points out some key problems influence geometric continuity and color fidelity in immersive projection environment.This thesis focus on improving the adaptive performance of the geometric calibration and the technique of reducing the non uniform irradiation and color deviation caused by inter-reflection,put forward more practical method,the main research work is as follows:1)To processing the geometric distortions of projected picture in the curved screen environment caused by slight movement of projector or screen position,a scene perception adaptive geometric calibrating method is proposed.This method using a scene perceptive self-calibration algorithm of projector-camera unit,observes the projection image with closed-loop feedback,extracting the projection screen and the scene features to calculate and optimize the projection transformation relationship,and realize the self-adaptive calibration without offline pre-correction.And the adaptive noise filtering algorithm based on dynamic sequence de bounce is adopted to improve the convergence efficiency of online adaptive geometric correction.This method can greatly improve the adaptability of on-line adaptive geometric correction under the condition of satisfying the correction precision of the sub-pixel level,and solves the problem that the traditional geometric calibration relies special auxiliary coding or pre-correction.2)To processing the light inter-reflection problem in concave projection environment,adaptive color compensation correction method is proposed for Lambertian and non-Lambertian surface.For Lambertian projection surface,an efficient algorithm of direct light and indirect light separation based on spectral reflectance curves is proposed,this algorithm combining the photometric stereo method for estimating the shape factor,and then use the standard radiometric compensation method to carry out adaptive inter-reflection color compensation and correction;For color deviation caused by inter-reflection phenomenon in non-Lambertian projection surface,a inter-reflection radiation model in non-diffuse environment is build.And uses the non-negative linear optimization method to optimize the radiometric energy output of each pixel to generate the compensation image.Finally,the effects of imaging color from inter-reflection is eliminated.3)Based on the key technologies above,the typical projection environment such as 120 degree cylinder and dome screen are constructed.With the application of the cultural heritage of immersive display as an example,it is proved that the algorithm can be applied to adaptive geometric calibrating and color correction of multi-projector,the effect is good.In this thesis,the self-adaptability of the multi-projection system is improved to make the process geometry calibration more efficient in the curved projection environment and effectively solve the problem of the inter-reflected phenomenon in the surrounding projection environment.Its practicality and high efficiency can meet the need of efficient automatic correction and high-fidelity display for most multi-projection systems,which is beneficial to the promotion of multi-projection display system in more fields.