水下目标物偏振成像特性研究

Experimental study on polarization imaging characteristics of underwater targets

偏振图像比传统强度图像包含更丰富的物体表面反射及散射信息。用萨尔萨(SALSA)相机在自然光照下获取水下偏振图像,研究不同材质物体、放置深度、牛奶浓度及波段因素对水下目标物偏振成像的影响。结果表明:蓝色波段偏振成像能够较好地获取水下物体的边界轮廓等信息;不同材质的目标物在水下呈现不同的偏振特性,紫铜偏振度最高达0.69;在1.40mg/L牛奶浑浊度的水下,偏振图像仍能通过比较目标物的偏振度(degree of polarization,DOP)信息来检测出水下目标物,瓷片的DOP仅降低0.31;此外,在水下约40cm深度下,偏振成像获取的图像比强度图像轮廓更为清晰,如铁的偏振对比度比强度对比度高5.26%。

Compared with the traditional intensity image,the polarization image contains more abundant information of the reflection and scattering of the object surface.The underwater polarizing image was acquired by SALSA camera under natural illumination.The influence of underwater objects,depth,milk concentration and detection band on polarization imaging detection was studied.The results show that in the blue band,the polarization imaging can obtain better information of the boundary contour of the underwater object.The objects of different materials present different polarization characteristics under the water,and the copper has the highest degree of polarization 0.69.Under the condition of milk turbidity 1.40 mg/L,the polarization image can still detect the underwater target by comparing the target object's degree of polarization(DOP)information,the DOP of porcelain only reduces by 0.31.In addition,The image obtained by polarizing imaging is clearer than the intensity image at the depth of about 40 cm underwater.For example,the polarization contrast of iron is 5.26% higher than that of intensity.