Differences in Growth Estimation and Yield Prediction of Rice Crop Using Satellites Data Simulated from near Ground Hyperspectral Reflectance

由近地面高解析光譜模擬之不同衛星光譜資料對水稻生長估測及產量預測產量上之差異

楊純明(Chwen-Ming Yang) ； 陳榮坤(Rong-Kuen Chen)

《航測及遙測學刊》 12卷1期 (2007/03) Pp. 93-105

https://doi.org/10.6574/JPRS.2007.12(1).8

摘要

Values of LAI(下標 NB) were found higher than those of LAI(下標 SPOT 5) and LAI(下標 FORMOSAT-2) on the same sampling dates yet all the estimates were lower than the corresponding values of LAI(下標 measured) after ca. 55 days after transplanting. As the simulated satellites data obtained lower values of NDVI and LAI than those of NDVI(下標 NB) and LAI(下標 NB) counterparts, yields predicted from satellites data were less than yield predicted from ground-based hyperspectral data.本研究以近地面量測之水稻植被窄頻高解析光譜模擬法國史波特五號(SPOT 5)及臺灣福衛二號(FORMOSAT-2)之寬頻光譜資料，俾利用於比較其等對水稻生長估測與產量預測上相對於近地面測值之差異。近地面植被高解析反射比光譜(reflectance spectrum)係由田間可攜式光譜儀(field-portable spectroradiometer)量測之，寬頻波段之反射比則以同波段各窄頻測值累加之平均值估算。根據試驗結果，由高解析光譜計算之標準化差植被指數(normalized difference vegetation index, NDVI(下標 NB))及模擬衛星寬頻光譜計算之標準化差植被指數（NDVI(下標 SPOT 5)及NDVI(下標 FORMOSAT-2)）均於一、二期稻作生育過程中呈現非線性分佈，且分佈曲線之間幾近平行變化，惟模擬衛星光譜資料之NDVI(下標 SPOT 5)與NDVI(下標 FORMOSAT-2)低於高解析光譜之NDVI(下標 NB)。地面實測葉面積計算之葉面積指數(LAI(下標 measured))與NDVI(下標 NB)之關係適用於指數生長型函數，據此將上述不同計算方式得到之NDVIs 輸入以獲得相對估測之葉面積指數（LAI(下標 NB)、LAI(下標 SPOT 5)及LAI(下標 FORMOSAT-2)）。結果發現約自移植後55天起，在同一取樣日之LAI(下標 NB)估值高於LAI(下標 SPOT 5)及LAI(下標 FORMOSAT-2)估值，惟這些葉面積指數估值概低於相對地面實測LAI(下標 measured)值。由於利用模擬衛星寬頻光譜資料獲得之NDVI及LAI估值低於近地面高解析光譜資料估算之相NDVI(下標 NB)及LAI(下標 NB)，因此以模擬衛星光譜資料預測之水稻產量低於近地面光譜資料預測之產量，且均低於實測產量。

關鍵字

水稻生長 ； 產量預測 ； 福衛二號衛星 ； 史波特五號衛星 ； 高解析光譜

並列摘要

The simulated broadband data of satellites SPOT 5 and FORMOSAT-2 were mimicked from canopy high-resolution reflectance spectra measured near ground, by a field-portable spectroradiometer, and these spectral data were then used to compare the differences in growth estimation and yield prediction of rice crop relative to those of ground measurements. Reflectance of broadband sensors was acquired by using the mean value of reflectance averaging over the respective waveband regions of hyperspectral data. Results indicated that the calculated values of normalized difference vegetation index (NDVIs) from hyperspectral (i.e. NDVI(subscript NB)) and simulated satellites data (i.e., NDVI(subscript SPOT 5) and NDVI(subscript fORMOSAT-2)) were all nonlinearly distributed during the first and second cropping seasons of rice. The curves were nearly parallel to each other, but values of NDVI(subscript SPOT 5) and NDVI(subscript FORMOSAT-2) were lower than those of NDVI(subscript NB). The relationship between the measured leaf area index (LAI(subscript measured)) and NDVI(subscript NB) was best fitted to an exponential growth function, by which the estimated values of LAI(subscript NB), LAI(superscript SPOT 5) and LAI(subscript FORMOSAT-2) were obtained using the respective NDVIs as inputs. Values of LAI(subscript NB) were found higher than those of LAI(subscript SPOT 5) and LAI(subscript FORMOSAT-2) on the same sampling dates yet all the estimates were lower than the corresponding values of LAI(subscript measured) after ca. 55 days after transplanting. As the simulated satellites data obtained lower values of NDVI and LAI than those of NDVI(subscript NB) and LAI(subscript NB) counterparts, yields predicted from satellites data were less than yield predicted from ground-based hyperspectral data. These predicted yields were all lower than the measured yields.

並列關鍵字

Rice growth ； Yield prediction ； FORMOSAT-2 ； SPOT 5 ； Hyperspectral data