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題 名 | TM SAVI修正因子最適值與林分密度估測之研究=Study on the Optimal Value of Adjustment Factor in TM SAVI for Estimate the Forest Canopy Closure |
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作 者 | 林金樹; | 書刊名 | 中華林學季刊 |
卷 期 | 32:3=126 1999.09[民88.09] |
頁 次 | 頁333-346 |
分類號 | 436.19 |
關鍵詞 | 森林; 林分密度; 遙測; 土壤修正植生指標; Forest; Canopy closure; Remote sensing; Soil-adjusted vegetation index; |
語 文 | 中文(Chinese) |
中文摘要 | 土壤修正植生指標(SAVI)利用一個修正因子以降低像元內背景物質對光譜反射量之影響,該修正因子之適當值與林分密度有顯著的負相關關係,應用SAVI時必須依據林木冠層的被覆狀態決定適當的修正值,方可有效的減低背景物之影響。由於森林之林木冠層被覆率並不很均一,故應用SAVI分析森林植群時,必需隨時依林區狀況調整其修正值,這種不便性無形中使遙測技術在林業實務上之應用受到限制。 本文使用玉井事業區的Landsat TM多譜資料與林分密度調查資料,建立以SAVI估測林分密度之適當模式,同時探討利用SAVI分析林分密度時,如何利用遙測多譜資料以簡易的方法來決定 SAVI 修正因子之最適值,以供未來森林資源調查應用之參考。 研究結果顯示,林分密度與TM SAVI有極顯著的線性關係,具最適修正值的SAVI比規整差植生指標(NDVI)對林分密度的估測效率約高出3%。由灰度值、輻射強度以及反射強度等三種光譜資料所導得的SAVI,其修正因子在林分密度估測模式中的最適值分別是60,5以及0.4,各屬於十位數級、個位數級、以及小數以下一位數的數級;這種數級分佈顯示SAVI最適修正值會隨紅光與近紅外光波段的光譜資料之值域而變,二者具有極強的正相關關係。當應用 TM多譜資料調查林分密度時,可以利用紅光及近紅外光波段的光譜資料均值決定SAVI的適當修正值,據以推估林分密度。 |
英文摘要 | There is a very close relationship between the soil-adjusted vegetation index (SAVI) and forest canopy closure. The uncertainty of optimal value of SAVI vegetation index adjustment factor would constrain its application on the estimation of forest canopy closure by remote sensing techniques. This paper tried to examine the relationship between TM SAVI and classified forest canopy closure, and to find the method of deciding the optimal adjustment factor of SAVI to estimate the forest canopy closure. The results showed that there was a positive linear relationship among the SAVIs and natural log transformed forest canopy closure. The optimum value of adjustment factor of SAVI that derived from gray level, radiance, and reflectance was 60, 5, and 0.4 respectively. This inferred that the optimum value of adjustment factor was very sensitive in TM data range. The increment of explained variation of forest canopy closure was about 3 percent for a regression model that composed by a suitable SAVI. The variation of classified forest canopy closure explained by the variable SAVI that with a suitable adjustment value was about 85%. We could use the mean of red and near infrared band to decide effectively the suitable value of adjustment factor in TM SAVI. |
本系統中英文摘要資訊取自各篇刊載內容。