基于高动态范围图像中光晕分析的光照方向测算算法

针对增强现实(AR)系统中复杂场景的光照一致性问题,运用高动态范围(HDR)图像处理技术对标识物图像进行分析,提出一种基于HDR图像中光晕分析的光照方向测算算法。为了提高虚拟物体的沉浸感和真实性,在研究和分析现有的光照恢复算法的基础上,利用二次曲线对的投影不变性原理进行相机标定;为了获得更加详尽的光照信息,使用HDR技术对标识物图像进行处理,提高了测算精确度;参照Lambert光照模型对图像中的光照信息进行分析,将拍摄角度进行分类,实现了对传统测算光源方向算法的改进,可测算出位于摄影球反射范围外的部分光源的方向,扩大了测算范围。设计了针对单一点光源的视角1和视角2测算验证实验,并进行了分析。实验验证表明,所提方法简单易行,具有较强的鲁棒性,能够实现在标识物部分遮挡的情况下,测算出位于摄影球反射范围外部分光源的方向。

Illumination direction measurement based on halo analysis in high-dynamic range images

Aiming at the illumination consistency of complex scenes in Augmented Reality (AR) system and analyzing the marker images by High-Dynamic Range (HDR) technology, an improved measurement algorithm for illumination direction based on the analysis of halo in HDR images was proposed. In order to improve the immersion and reality of virtual objects, after researching and analyzing the existing illumination recovery algorithms, a camera calibration method was proposed by utilizing the projection invariance of the quadratic curve pair. In order to get detailed light information, HDR was used to process marker image to improve accuracy. Refering to Lambert illumination model, the light information of image was analyzed to classify the shooting angle, and the improvement of traditional light source direction measuring was realized, part of the directions of the light sources outside of the photography ball reflection range was measured. The shooting 1 and shooting 2 of the single point light source were tested and analyzed. The experimental results show that this method is simple, robust, and can measure the direction of partial illumination outside the mirror ball reflection range no matter whether the marker is partially shaded or not.