加入高程因子的航空高光谱影像大气辐射校正
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摘要
地形效应是影响遥感定量分析的主要障碍之一。尤其对于航空高光谱遥感而言,其地形效应更为显著,地形高程、角度带来的影响都不可忽略。基于青海雪鞍山地区的CASI高光谱影像和LiDAR地形数据,开展地形高程变化对航空高光谱遥感的影响研究。在假定每一个高程点为水平朗伯体的前提下,首先,基于MODTRAN软件模拟计算不同高程对应的大气上行辐射、地物至传感器之间的大气透过率、大气半球反照率和下行总辐射,进行地形高程变化对4个参量的影响分析;然后,设计实现了加入高程因子的大气辐射校正,完成了测区航空高光谱影像的反射率反演计算;最后,与FLAASH大气校正的反射率结果进行比较,发现同类地物的反射率曲线在谱形方面接近,但反射率数值存在差异,尤其是FLAASH大气校正结果中短波波段甚至出现负值,无疑是错误的。实验表明,高程因子的变化对山地航空高光谱影像成像过程的影响不可忽略,要实现精确的航空高光谱影像大气辐射校正必须消除其影响。
Topographic effect is one of the main obstacles in quantitative analysis of remote sensing. For the airborne hyperspectral remote sensing,both of the impact of terrain height and angle can't be ignored,and this causes more severe topographic effects. By taking the CASI image and Li DAR data of Qinghai Province as experimental data,the impact of elevation factor was analyzed in this paper. Firstly,on the premise that each elevation point is a horizontal Lambert body,four different elevation values were taken as reference to calculate the corresponding atmospheric radiation correction parameters by performing MODTRAN,which contain path radiance,atmospheric transmittance between the object and the sensor,atmospheric hemisphere albedo,and total downward radiance. Then an atmospheric radiation correction method with elevation factor was designed and applied to the atmospheric correction of CASI image. Finally, the CASI hyperspectral image was also processed by using FLAASH,which could only take one elevation value as reference. A comparison of two results shows that the reflectance spectrum shapes of the same ground objects are roughly the same,but the reflectance values are different. Especially, the short-wavelength reflectance values of FLAASH results are negative, and it is undoubtedly wrong. The experiment shows that the impact of elevation factors can't be neglected. Atmospheric correction by adding elevation factors can get better results. For achieving accurate topographic correction of airborne hyperspectral image,both elevation and topographic angle factors should be considered simultaneously.
Topographic effect is one of the main obstacles in quantitative analysis of remote sensing. For the airborne hyperspectral remote sensing,both of the impact of terrain height and angle can't be ignored,and this causes more severe topographic effects. By taking the CASI image and Li DAR data of Qinghai Province as experimental data,the impact of elevation factor was analyzed in this paper. Firstly,on the premise that each elevation point is a horizontal Lambert body,four different elevation values were taken as reference to calculate the corresponding atmospheric radiation correction parameters by performing MODTRAN,which contain path radiance,atmospheric transmittance between the object and the sensor,atmospheric hemisphere albedo,and total downward radiance. Then an atmospheric radiation correction method with elevation factor was designed and applied to the atmospheric correction of CASI image. Finally, the CASI hyperspectral image was also processed by using FLAASH,which could only take one elevation value as reference. A comparison of two results shows that the reflectance spectrum shapes of the same ground objects are roughly the same,but the reflectance values are different. Especially, the short-wavelength reflectance values of FLAASH results are negative, and it is undoubtedly wrong. The experiment shows that the impact of elevation factors can't be neglected. Atmospheric correction by adding elevation factors can get better results. For achieving accurate topographic correction of airborne hyperspectral image,both elevation and topographic angle factors should be considered simultaneously.
引文
[1] Schaaf C,Li X,Strahler A. Topographic effects on bidirectional and hemispherical reflectances calculated with a geometric-optical canopy model[J]. IEEE Transactions on Geoscience and Remote Sensing,1994,32(6):1186-1193.
[2] Oliphant A J,Spronken-Smith R A,Sturman A P,et al. Spatial variability of surface radiation fluxes in mountainous terrain[J].Journal of Applied Meteorology,2003,42(1):113-128.
[3] Wen J G,Zhao X J,Liu Q,et al. An improved land-surface albedo algorithm with DEM in rugged terrain[J]. IEEE Geoscience and Remote Sensing Letters,2014,11(4):883-887.
[4]李爱农,边金虎,张正健,等.山地遥感主要研究进展、发展机遇与挑战[J].遥感学报,2016,20(5):1199-1215.Li A N,Bian J H,Zhang Z J,et al. Progresses,opportunities,and challenges of mountain remote sensing research[J]. Journal of Remote Sensing,2016,20(5):1199-1215.
[5]宫鹏.遥感科学与技术中的一些前沿问题[J].遥感学报,2009,13(1):13-23.Gong P. Some essential questions in remote sensing science and technology[J]. Journal of Remote Sensing,2009,13(1):13-23.
[6]王少楠,李爱农.地形辐射校正模型研究进展[J].国土资源遥感,2012,24(2):1-6. doi:10. 6046/gtzyyg. 2012. 02. 01.Wang S N,Li A N. The progress in the study of topographic radiometric correction models[J]. Remote Sensing for Land and Resources,2012,24(2):1-6. doi:10. 6046/gtzyyg. 2012. 02. 01.
[7]黄博,徐丽华.基于改进型Minnaert地形校正模型的应用研究[J].遥感技术与应用,2012,27(2):183-189.Huang B,Xu L H. Applied research of topographic correction based on the improved Minnaert model[J]. Remote Sensing Technology and Application,2012,27(2):183-189.
[8] Lu D S,Ge H L,He S Z,et al. Pixel-based Minnaert correction method for reducing topographic effects on a Landsat 7 ETM+image[J]. Photogrammetric Engineering and Remote Sensing,2008,74(11):1343-1350.
[9] Wen J G,Liu Q H,Liu Q,et al. Parametrized BRDF for atmospheric and topographic correction and albedo estimation in Jiangxi rugged terrain,China[J]. International Journal of Remote Sensing,2009,30(11):2875-2896.
[10] Li A N,Wang Q F,Bian J H,et al. An improved physics-based model for topographic correction of Landsat TM images[J]. Remote Sensing,2015,7(5):6296-6319.
[11] Richter R,Kellenberger T,Kaufmann H. Comparison of topographic correction methods[J]. Remote Sensing,2009,1(3):184-196.
[12] Hantson S,Chuvieco E. Evaluation of different topographic correction methods for Landsat imagery[J]. International Journal of Applied Earth Observation and Geoinformation,2011,13(5):691-700.
[13] Balthazar V,Vanacker V,Lambin E F. Evaluation and parameterization of ATCOR3 topographic correction method for forest cover mapping in mountain areas[J]. International Journal of Applied Earth Observation and Geoinformation,2012,18(1):436-450.
[14]童庆禧,张兵,郑兰芬.高光谱遥感———原理、技术与应用[M].北京:高等教育出版社,2006:86-105.Tong Q X,Zhang B,Zheng L F. Hyperspectral Remote Sensing:Principle,Technology and Applications[M]. Beijing:Higher Education Press,2006:86-105.
[15] Adler-Golden S M,Matthew M W,Bernstein L S,et al. Atmospheric correction for short-wave spectral imagery based on MODTRAN4[J]. Proceedings of SPIE,the International Society for Optical Engineering,1999,3753:61-69.
[16] Kaufman Y J. Atmospheric effect on spectral signature-measurements and corrections[J]. IEEE Transactions on Geoscience and Remote Sensing,1988,26(4):441-450.
[17] Anderson G P,Felde G W,Hoke M L,et al. MODTRAN4-based atmospheric correction algorithm:FLAASH(fast line-of-sight atmospheric analysis of spectral hypercubes)[J]. Proceedings of SPIE,the International Society for Optical Engineering,2002,4725:65-71.
[2] Oliphant A J,Spronken-Smith R A,Sturman A P,et al. Spatial variability of surface radiation fluxes in mountainous terrain[J].Journal of Applied Meteorology,2003,42(1):113-128.
[3] Wen J G,Zhao X J,Liu Q,et al. An improved land-surface albedo algorithm with DEM in rugged terrain[J]. IEEE Geoscience and Remote Sensing Letters,2014,11(4):883-887.
[4]李爱农,边金虎,张正健,等.山地遥感主要研究进展、发展机遇与挑战[J].遥感学报,2016,20(5):1199-1215.Li A N,Bian J H,Zhang Z J,et al. Progresses,opportunities,and challenges of mountain remote sensing research[J]. Journal of Remote Sensing,2016,20(5):1199-1215.
[5]宫鹏.遥感科学与技术中的一些前沿问题[J].遥感学报,2009,13(1):13-23.Gong P. Some essential questions in remote sensing science and technology[J]. Journal of Remote Sensing,2009,13(1):13-23.
[6]王少楠,李爱农.地形辐射校正模型研究进展[J].国土资源遥感,2012,24(2):1-6. doi:10. 6046/gtzyyg. 2012. 02. 01.Wang S N,Li A N. The progress in the study of topographic radiometric correction models[J]. Remote Sensing for Land and Resources,2012,24(2):1-6. doi:10. 6046/gtzyyg. 2012. 02. 01.
[7]黄博,徐丽华.基于改进型Minnaert地形校正模型的应用研究[J].遥感技术与应用,2012,27(2):183-189.Huang B,Xu L H. Applied research of topographic correction based on the improved Minnaert model[J]. Remote Sensing Technology and Application,2012,27(2):183-189.
[8] Lu D S,Ge H L,He S Z,et al. Pixel-based Minnaert correction method for reducing topographic effects on a Landsat 7 ETM+image[J]. Photogrammetric Engineering and Remote Sensing,2008,74(11):1343-1350.
[9] Wen J G,Liu Q H,Liu Q,et al. Parametrized BRDF for atmospheric and topographic correction and albedo estimation in Jiangxi rugged terrain,China[J]. International Journal of Remote Sensing,2009,30(11):2875-2896.
[10] Li A N,Wang Q F,Bian J H,et al. An improved physics-based model for topographic correction of Landsat TM images[J]. Remote Sensing,2015,7(5):6296-6319.
[11] Richter R,Kellenberger T,Kaufmann H. Comparison of topographic correction methods[J]. Remote Sensing,2009,1(3):184-196.
[12] Hantson S,Chuvieco E. Evaluation of different topographic correction methods for Landsat imagery[J]. International Journal of Applied Earth Observation and Geoinformation,2011,13(5):691-700.
[13] Balthazar V,Vanacker V,Lambin E F. Evaluation and parameterization of ATCOR3 topographic correction method for forest cover mapping in mountain areas[J]. International Journal of Applied Earth Observation and Geoinformation,2012,18(1):436-450.
[14]童庆禧,张兵,郑兰芬.高光谱遥感———原理、技术与应用[M].北京:高等教育出版社,2006:86-105.Tong Q X,Zhang B,Zheng L F. Hyperspectral Remote Sensing:Principle,Technology and Applications[M]. Beijing:Higher Education Press,2006:86-105.
[15] Adler-Golden S M,Matthew M W,Bernstein L S,et al. Atmospheric correction for short-wave spectral imagery based on MODTRAN4[J]. Proceedings of SPIE,the International Society for Optical Engineering,1999,3753:61-69.
[16] Kaufman Y J. Atmospheric effect on spectral signature-measurements and corrections[J]. IEEE Transactions on Geoscience and Remote Sensing,1988,26(4):441-450.
[17] Anderson G P,Felde G W,Hoke M L,et al. MODTRAN4-based atmospheric correction algorithm:FLAASH(fast line-of-sight atmospheric analysis of spectral hypercubes)[J]. Proceedings of SPIE,the International Society for Optical Engineering,2002,4725:65-71.