基于图像拼接技术的大视场流体可视化纹影系统

Large field fluid visualization schlieren system based on image mosaic technology

针对纹影系统中视场越大,需要的抛物面反射镜面积也越大,相应的配套设施也更复杂、场地占用更大、制造成本更高等问题,在纹影技术的基础上,提出制造一套小型化、低成本,但同样可以实现大视场观测的流场可视化纹影系统。基于单反射镜离轴纹影系统的光路设计,加入机械升降结构,实现类似扫描的图像采集模式。同时,结合计算机图像处理技术对大视场纹影系统采集到流场不同位置的纹影图像进行处理,再利用基于SURF算法的图像拼接技术对各部分纹影图像进行全景图像合成。实验结果表明:提出的基于图像拼接技术的大视场流体可视化系统,相对于造价高昂的500 mm以上口径纹影系统,可以获得更广的观测视野。

In schlieren system,the larger the field of view,the larger the area of paraboloid mirror.At the same time,the corresponding supporting facilities are also more complex,the site occupation is larger,and the manufacturing cost is higher.Based on schlieren technology,a small,low-cost flow visualization schlieren system is proposed,which can also realize large field of view observation.Based on the optical path design of off-axis schlieren system with single reflector,a mechanical lifting structure is added to realize the image acquisition mode similar to scanning.At the same time,combined with computer image processing technology,the schlieren images at different positions of the flow field collected by the large field schlieren system are processed.Then,the image mosaic technology based on surf algorithm is used to synthesize the panoramic image of each schlieren image.The experimental results show that the large field of view fluid visualization system based on image mosaic technology proposed in this paper can obtain a wider observation field than the expensive schlieren system with an aperture of more than 500 mm.