User-oriented image quality assessment of ZY-3 product in agriculture area

ZY-3 (Ziyuan 3—Resouces 3) is the first three-array high resolution mapping satellite in China and was launched in 2012 spring, providing 2.1 meter resolution panchromatic image product and 5.8 meter multispectral image product for implementing topographical mapping and observation on land resource. A number of evaluations have been taken in the aspects of its imagery method, geometric quality and radiometric characteristics of panchromatic camera. As the complement, this paper presents an evaluation of its image product's user-oriented quality and potential usability in agriculture area, by the objective and the subjective means respectively. In order to better understand the level of quality of the ZY-3 image and the scope of their agriculture applications, a comparison of image quality factors is made between ZY-3 image and SPOT-5 image which has a very similar functionality. By the objective means, we make statistical analysis on the gray scale characteristics and the texture characteristics of the images on different regions from satellites respectively, and choose one same region for comparison. The grey scale statistic features on the ZY-3 image shows the advantage in its wider data range, higher mean, higher standard deviation and a better histogram presenting in distinct areas; especially the mean differential calculation of all bands shows a more balanced energy distribution in ZY-3's band configuration. The analysis of texture from the two images reveals that ZY-3 image also has better texture performance than SPOT-5 with respect to homogeneity, contrast, entropy and second moment. As far as the subjective analysis for the quality, image visual element effect and National Imagery Interpretability Rating Scale (NIIRS) is adopted for the evaluation of overall image quality in terms of visual sense. A conducted survey shows ZY-3 images have better legibility and recognition on agriculture area with the help of its high spatial resolution and good radiometric quality.