Aiming at the characteristics of infrared video,a three-dimensional reconstruction method of monocular infrared video based on direct and sparse visual odometer is proposed.In this method,the internal parameters of the thermal imager are obtained by the calibration of the infrared camera,and then the direct and sparse visual odometer model is constructed.Visual odometer front-end performs frame management and point management tasks.The total photometric error is optimized by the sliding window and the Gauss-Newton iteration,and all the variables that the direct and sparse visual odometer model needs are calculated.Finally,the tasks of locating the thermal imager and plotting are fullfilled.Experimental results show that the proposed method can achieve the three-dimensional reconstruction of monocular infrared video in real time.