Department of Electronics, University of Alcalá, Alcalá de Henares, Madrid, Spain.
Sensors (Basel). 2010;10(4):4159-79. doi: 10.3390/s100404159. Epub 2010 Apr 26.
In this article, we present a real-time 6DoF egomotion estimation system for indoor environments using a wide-angle stereo camera as the only sensor. The stereo camera is carried in hand by a person walking at normal walking speeds 3-5 km/h. We present the basis for a vision-based system that would assist the navigation of the visually impaired by either providing information about their current position and orientation or guiding them to their destination through different sensing modalities. Our sensor combines two different types of feature parametrization: inverse depth and 3D in order to provide orientation and depth information at the same time. Natural landmarks are extracted from the image and are stored as 3D or inverse depth points, depending on a depth threshold. This depth threshold is used for switching between both parametrizations and it is computed by means of a non-linearity analysis of the stereo sensor. Main steps of our system approach are presented as well as an analysis about the optimal way to calculate the depth threshold. At the moment each landmark is initialized, the normal of the patch surface is computed using the information of the stereo pair. In order to improve long-term tracking, a patch warping is done considering the normal vector information. Some experimental results under indoor environments and conclusions are presented.
在本文中，我们提出了一种使用广角立体相机作为唯一传感器的实时 6DoF 运动估计系统，用于室内环境。立体相机由以 3-5 公里/小时的正常步行速度行走的人手持。我们提出了一种基于视觉的系统的基础，该系统可以通过不同的传感模式为视障人士提供有关其当前位置和方向的信息，或者引导他们到达目的地，从而协助他们导航。我们的传感器结合了两种不同类型的特征参数化：逆深度和 3D，以便同时提供方位和深度信息。从图像中提取自然地标，并根据深度阈值将其存储为 3D 或逆深度点。该深度阈值用于在两种参数化之间切换，并且通过立体传感器的非线性分析来计算。还介绍了我们系统方法的主要步骤以及计算深度阈值的最佳方法的分析。在每个地标初始化的那一刻，使用立体对的信息计算斑块表面的法线。为了提高长期跟踪能力，考虑到法向量信息进行了斑块变形。还介绍了一些在室内环境下的实验结果和结论。
