# 计算机视觉 (光流，MoCap， VIO，避障)
计算机视觉 (opens new window) 技术使计算机能够使用视觉数据来理解他们的环境。
PX4使用计算机视觉系统(主要在机载计算机上运行)以支持下列功能：
- 光流提供 2D 速度估计（使用向下的相机和向下的距离传感器）。
- Motion Capture provides 3D pose estimation using a vision system that is external to the vehicle. 它主要用于室内导航。
- Visual Inertial Odometry provides 3D pose and velocity estimation using an onboard vision system and IMU. It is used for navigation when global position information is absent or unreliable. 当 GPS 不存在或不可靠时，它用于导航。
- Obstacle Avoidance (opens new window) provides navigation around obstacles when flying a planned path (currently missions are supported). This uses PX4/avoidance (opens new window) running on a companion computer. 利用机载计算机上运行的PX4/PX4-Avoidance (opens new window)
- Collision Prevention (opens new window) is used to stop vehicles before they can crash into an obstacle (primarily when flying in manual modes).
Motion Capture (MoCap) is a technique for estimating the 3D pose (position and orientation) of a vehicle using a positioning mechanism that is external to the vehicle. MoCap systems most commonly detect motion using infrared cameras, but other types of cameras, Lidar, or Ultra Wideband (UWB) may also be used. It comes with no pre-installed software, but does include an example implementation of obstacle avoidance to demonstrate the capabilities of the platform. :::
# 运动捕捉
Motion Capture (MoCap) is a technique for estimating the 3D pose (position and orientation) of a vehicle using a positioning mechanism that is external to the vehicle. MoCap systems most commonly detect motion using infrared cameras, but other types of cameras, Lidar, or Ultra Wideband (UWB) may also be used.
注解
MoCap is commonly used to navigate a vehicle in situations where GPS is absent (e.g. indoors), and provides position relative to a local coordinate system. 它通常用于在GPS不存在（例如室内）或不可靠的情况下（例如在桥下飞行时）导航载具。
有关 MoCap 的信息，请参阅：
# 视觉惯性里程计（VIO）
Visual Inertial Odometry (VIO) is used for estimating the 3D pose (position and orientation) and velocity of a moving vehicle relative to a local starting position. 它通常用于在 GPS 不存在（例如室内）或不可靠的情况下（例如在桥下飞行时）给无人机导航。
VIO uses Visual Odometry (opens new window) to estimate vehicle pose from visual information, combined with inertial measurements from an IMU (to correct for errors associated with rapid vehicle movement resulting in poor image capture).
VIO
和 MoCap 之间的区别在于 VIO 相机或者 IMU 是基于无人机的，并且额外提供速度信息。
关于在 PX4 上配置 VIO 的信息，请参阅：
# 光流
光流提供 2D 速度估计（使用向下的相机和向下的距离传感器）。
有关光流的信息，请参阅：
# 外部资源
- XTDrone (opens new window) - ROS + PX4 计算机视觉模拟仿真环境。 XTDrone 手册 (opens new window) 有你需要开始的一切！