thread: visual-inertial odometry

remove noisy points

* @brief IMU预积分传播方程 * @Description 积分计算两个关键帧之间IMU测量的变化量： * 旋转delta_q 速度delta_v 位移delta_p * 加速度的biaslineari

* Sets the timestamp from seconds and microseconds * @param secs: seconds * @param usecs: microseconds */

real marginalization is removed in solve_ceres()

real marginalization is removed in solve_ceres()

* \brief Project a 3D point (\a x,\a y,\a z) to the image plane in (\a u,\a v) * * \param P 3D point coordinates * \param p return value, contains