Although many saliency models for images had been proposed, the saliency model for stereoscopic omnidirectional image (SOI) is still a very important but not yet deeply studied topic. In addition, one of main disadvantages of the existing saliency models is difficult to simulate the characteristics of a wide field of view (FOV) of SOIs. To solve the problems, this paper proposes a novel cube map projection (CMP) based saliency model for SOIs. Considering that the equi-rectangular projection (ERP) representation of SOI will result in obvious stretch distortion, and what the human eyes view are the viewport images by using head mounted display (HMD), we construct the saliency model of the SOI in its less shape distorted CMP plane. First, the SOI with ERP format is converted into the CMP format. In order to reduce the boundary effect between the faces in CMP plane, its four horizontal faces are moved to obtain the horizontal global face and the horizontal local faces for which the corresponding saliency maps are subsequently computed by combining color distance and depth distance in the graph model. Then, to establish the correlations of these faces, the horizontal face saliency map is calculated by weighting the horizontal global face saliency map to the horizontal local face saliency map. Meanwhile, the vertical face saliency map is defined and obtained. Finally, the horizontal face saliency map and vertical face saliency map are spliced and re-projected to ERP plane to obtain the final saliency map of the ERP-mapped SOI. The experiments on the public ODI database are performed to compare the proposed methods with the state-of-the-art methods, and the results show that the proposed method achieves better performance of estimating SOI saliency map in terms of six well-known quantitative metrics.

尽管提出了许多图像显着性模型，但立体全向图像（SOI）的显着性模型仍然是一个非常重要但尚未深入研究的主题。另外，现有显着性模型的主要缺点之一是难以模拟SOI的宽视场（FOV）的特征。为了解决这些问题，本文提出了一种基于新的基于立方体地图投影（CMP）的SOI显着性模型。考虑到SOI的等角投影（ERP）表示会导致明显的拉伸变形，而人眼所看到的是使用头戴式显示器（HMD）的视口图像，因此我们在SOI的显着性模型中形状变形的CMP平面。首先，将具有ERP格式的SOI转换为CMP格式。为了减少CMP平面中各个面之间的边界效应，移动其四个水平面以获得水平全局面和水平局部面，随后通过将图形中的颜色距离和深度距离相结合来计算对应的显着性图模型。然后，为了建立这些面部的相关性，通过将水平全局面部显着图加权到水平局部面部显着图来计算水平面部显着图。同时，定义并获得了垂直面部显着图。最后，将水平人脸显着图和垂直人脸显着图进行拼接，然后重新投影到ERP平面，以获得ERP映射的SOI的最终人显着图。