| 摘要 |
A method comprising, capturing a sequence of image frames Fj by a portable device camera; obtaining movement data by using an inertial sensor of the portable device; determining a sampling frame rate fA according to the movement data; selecting a tracking image IMGk from the captured image frames according to the sampling frame rate; determining a position of the portable device by comparing the tracking image with a point cloud PCk; and displaying information on a display of the device based on the determined position. The sampling frame rate may be an integer divisor of the rate at which image frames are captured fSEQ. Preferably the sample rate is strictly less than the capture rate when the angular velocity and acceleration of the device is small, and equal to the capture rate when the angular velocity and acceleration is high. Optionally, a blurring value of each point in the point cloud is determined based on movement data, a subset of the 3D point cloud is chosen based on the blurring values, and the position of the camera is determined using the chosen subset. Preferably the sampling rate is increased when the number of matching features in the tracking image is low. Corresponding device claims are included. |
