Li Dajin, Bai Chengjie. Depth mapping in real-time stereoscopic systems[J]. Journal of Image and Graphics, 2015, 20(3): 366-373. DOI: 10.11834/jig.20150308.
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. 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. 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. 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