Crop Geometry Identification Based on Inversion of Semiempirical BRDF Models
ZHAO Chun-jiang1, HUANG Wen-jiang1,2*, MU Xu-han2, WANG Jin-di2, WANG Ji-hua1
1. National Engineering Research Center for Information Technology in Agriculture, Beijing 100097, China 2. State Key Laboratory of Remote Sensing Science, School of Geography, Beijing Normal University, Beijing 100875, China
Abstract：With the rapid development of remote sensing technology, the application of remote sensing has extended from single view angle to multi-view angles. It was studied for the qualitative and quantitative effect of average leaf angle (ALA) on crop canopy reflected spectrum. Effect of ALA on canopy reflected spectrum can not be ignored with inversion of leaf area index (LAI) and monitoring of crop growth condition by remote sensing technology. Investigations of the effect of erective and horizontal varieties were conducted by bidirectional canopy reflected spectrum and semiempirical bidirectional reflectance distribution function (BRDF) models. The sensitive analysis was done based on the weight for the volumetric kernel (fvol), the weight for the geometric kernel (fgeo), and the weight for constant corresponding to isotropic reflectance (fiso) at red band (680 nm) and near infrared band (800 nm). By combining the weights of the red and near-infrared bands, the semiempirical models can obtain structural information by retrieving biophysical parameters from the physical BRDF model and a number of bidirectional observations. So, it will allow an on-site and non-sampling mode of crop ALA identification, which is useful for using remote sensing for crop growth monitoring and for improving the LAI inversion accuracy, and it will help the farmers in guiding the fertilizer and irrigation management in the farmland without a priori knowledge.
Key words：Bidirectional reflectance distribution function (BRDF);Crop geometry;Sensitivity Analysis;Average leaf angle (ALA)
[1] ZHOU Yun-hua, XIANG Yue-qin, LIN Zhong-hui(周允华, 项月琴, 林忠辉). Chinese Journal of Applied Ecology(应用生态学报), 1997, 8(1): 21. [2] HU Yan-ji, LAN Jin-hao(胡延吉, 兰进好). Chinese Journal of Agrometeorology(中国农业气象), 2001, 22(3): 28. [3] LI Shao-kun, WANG Chong-tao(李少昆, 王崇桃). Journal of Shihezi University(Natural Science Edition)(石河子大学学报·自然科学版), 1997, 1(3): 250. [4] Maddonoi G A, Otegui M E. Field Crops Research, 1996, 48: 81. [5] Hikosaka K, Hirose T. Ecoscience, 1997, 4(4): 501. [6] Utsugi H. Trees Structure and Function, 1999, 14(1): 1. [7] Pepper G E, Pearce R B, Mock J J. Crop Science, 1977, 17(6): 883. [8] HUANG W J, NIU Z, WANG J H, et al. IEEE Transactions on Geoscience and Remote Sensing, 2006, 44 (12): 3601. [9] Goel N S，Strebel D E. Agronomy Journal, 1984, 76: 800. [10] Li X W, Strahler A H. IEEE Transactions on Geoscience and Remote Sensing, 1985, 23 (5): 705. [11] LI Xiao-wen, GAO Feng, WANG Jin-di, et al(李小文, 高 峰, 王锦地, 等). Journal of Remote Sensing(遥感学报), 1997, 1(1): 5. [12] Li X, Strahler A H. IEEE Transactions on Geoscience and Remote Sensing, 1992, 30(2): 276. [13] GAO F, Schaaf C B, Strahler A H, et al. Remote Sensing of Environment, 2003, 86: 198. [14] Sandmeier S T, Muller C H, Hosgood B, et al. Remote Sensing of Environment, 1998, 66: 222.
