Photogrammetry and visio-measurement
Close-range and aerial photogrammetry, feature matching and 3D reconstruction.
Machine visio，Precise industry measurement，Camera calibration，Computer-aided 3D reconstruction
1. Geometric correction of UAV image based on the POS system：develop UAV hyperspectral imaging system. The loads on UAV include IMU, GPS and push-sweep type hyperspectral cameras. Due to the violent shaking of UAV, each line in the image will have overlap or gaps, which can lead to a serious distortion for feature presentation. With position and attitude information acquired from POS data, transform among the camera coordinate system, navigation coordinate system, WGS84 coordinate system and ground mapping coordinate system, do geometric correction with the aid of collinear equation and image resampling.
2. UAV images rapid mosaic and 3D reconstruction：
Restore the position and posture of the camera from input images through SFM algorithm which contains feature points extraction and matching and Bundler; Camera calibration; dense point clouds produced through per-pixel dense matching. Get refined 3D point clouds through point cloud denoising and filtering. Realize texture map by triangulation. This software system can realize rapid image mosaicking and three-dimensional modeling from large amount of UAV image data.
3. UAV& camera control system： With GPS and high resolution camera on the UAV, combined with FPGA hardware and track planning control algorithm, decide whether to choose a long exposure time and gain adjustment for special area when arriving in a particular area. Realization of simple intelligent control for UAV.
4. development on Digital camera geometric calibration software system：
In Cooperation with a drone enterprises of surveying and mapping in Beijing. Using total station to build a three-dimensional control field, the DLT algorithm is adopted. It involves adjustment and iteration algorithm, to achieve internal distortion calibration for digital camera.
5. A technology to calibrate relative orientation between industrial camera and structured light：
By means of the theodolite, line laser, camera and related software, the camera can capture the laser plane’s normal equation in camera space coordinates and the relation between camera and laser device can be calibrated. We can use it to scan point cloud and measure 3D object.
6. Research and development of binocular vision high-speed dynamic digital photogrammetry system：
establish two stereo cameras, and attach mark targets onto the object under test. The process involves image processing, internal and external elements calibration, basic development of control for camera and multithreaded synchronization technology to ensure that the two different cameras function synchronously. Calculate 3D point coordinates of the object according to the forward intersection; Through FFT algorithm, the time domain can be transformed into frequency domain and real-time spectrum diagram can be generated. This software can be used to measure the displacement and frequency of vibrating object.
- Qiang Wang, Haimeng Zhao*, Zhenxin Zhang, Ximin Cui*, Sana Ullah, Shanlin Sun,Fan Liu; Line Matching Based on Viewpoint-Invariance for Stereo Wide-Baseline Aerial Images . Applied Science 2018, 8(6), 938, 10.3390/app8060938.
- Qiang Wang, Lei Yan, Yanbiao Sun*, Ximin Cui, hugh.mortimer, Yanyan Li; True orthophoto generation using line segment matches. Photogrammetric Record 2018, 33(161), 113-130, 10.1111/phor.12229.