Camera-projector calibration for near infrared imaging system

Advanced biomedical engineering technologies are continuously changing the medical practices to improve medical care for patients. Needle insertion navigation during intravenous catheterization process via Near infrared (NIR) and camera-projector is one solution. However, the central point of the problem is the image captured by camera misaligns with the image projected back on the object of interest. This causes the projected image not to be overlaid perfectly in the real-world. In this paper, a camera-projector calibration method is presented. Polynomial algorithm was used to remove the barrel distortion in captured images. Scaling and translation transformations are used to correct the geometric distortions introduced in the image acquisition process. Discrepancies in the captured and projected images are assessed. The accuracy of the image and the projected image is 90.643%. This indicates the feasibility of the captured approach to eliminate discrepancies in the projection and navigation images.

Multi-Projector Calibration Based on Virtual Viewing Space

In large-scale maritime maneuvering simulators, the multi-channel systems are usually used to tile multiple projectors on a cylindrical display to create a large virtual environment, which brings more realistic immersion to the users. In the non-planar multi-projector display system, to finish the work of geometric and photometric corrections, there exist the problems of difficult projector calibration, more manual intervention and poor adaptability. In order to solve these problems, a multi-projector calibration based on virtual viewing space is proposed in this paper. First, a virtual environment of multiple projectors is created, and by using the structured light and re-projection model on a cylindrical wall, the calibration of internal and external parameters of a projector are realized separately. Finally, the geometric correction is completed by the mapping relationship between the target images and the calibrated re-projected images. This method is free of limitation by the angle of view of a single camera and can calibrate any of the projectors in the multi-channel systems. The example results show that the projector’s parameters can be estimated more accurately, and the efficiency and accuracy of geometric correction can be improved. Good results are achieved when applying this method in the maritime maneuvering simulator system.