目的 为减少立体图像中由于水平视差过大引起的视觉疲劳。针对实时渲染的立体视觉系统,给出了一种非均匀深度压缩方法。方法 该方法在单一相机空间内,通过不同的投影变换矩阵生成双眼图像,水平视差由投影变换来控制。为减少深度压缩造成的模型变形而带来的瑕疵,将不同深度区域内物体施以不同的压缩比例;将相机轴距表示为深度的连续函数,通过相机轴距推导出在单一相机空间内获取双眼图像的坐标变换,将深度压缩转换为模型的坐标变换,从而保证压缩比例的连续变化。结果 实验结果表明,该方法能有效提高立体图像的质量。结论 该方法简单、高效,可应用于游戏、虚拟现实等实时立体视觉系统。

Objective In the creation of stereoscopic 3D images, the use of parallax adjustment to alleviate the visual discomfort caused by large perceived depth range is of great importance. This process is called perceived depth mapping or parallax mapping. Most existing depth mapping methods control the horizontal parallax by changing the camera parameters, such as the inter-axis distance and focal length, or by warping local images during the post process. However, these methods cannot be used in real-time rendering systems. This study proposes an efficient and non-uniform depth compression model for real-time stereoscopic systems. Method On the basis of the geometry deduction on a horizontal parallax produced by two cameras, we use a single camera to capture two image views with different projection matrices that correspond to two viewing points. A horizontal parallax can be created through simple shearing transformation. Depth compression can cause object deformations (i.e., objects appear flattened). To reduce the artifacts caused by object deformations, different compression ratios are applied at various viewing depths. Given that the areas around the screen are the most comfortable zones and that humans tend to focus on these zones, we apply a small compression ratio for objects near the projection plane and a large compression ratio for far objects. For a smooth change in compression ratio, the relation of the inter-axis distance with the view depth of the camera is defined as a continuous linear function, and the projection transformation for the two views is derived on the basis of the inter-axis distance function. Non-uniform depth mapping is modeled with three processes: horizontal warping, shearing, and normal projection transformation. Result Experimental results show that our depth compression method can ensure a smooth variation in the compression ratio.The proposed method effectively improves stereoscopic image quality. The warping of objects before projection cannot be identified in the final stereoscopic images. Conclusion Our study shows that depth mapping can be realized through geometry transformation for virtual 3D scenes.The non-uniform depth compression method is simple, highly efficient, and can be applied to real-time stereoscopic systems, such as games and virtual reality.