ENGLISH

4卷/1期

4卷/1期

華藝線上圖書館

Pages:

1-17

論文名稱

AVHRR 資料估算台灣地區植被指數研究: (1) 幾何套合處理

Title

Applying AVHRR Data to Estimate the Vegetation Index of Taiwan Area: (Ⅰ) Geometrical Registration

作者

劉振榮, 羅煥奎, 郭宗華

Author

Gin-Rong Liu, Huαn-Kuei Lo, Tsung-Huα Kuo

中文摘要

植被指數資料可顯示生物圈植被生長的分布狀態與異常情形,故其可對肇因於人為或自然的環境變化,提供一長期的指標,但截至目前為止,尚無對台灣地區植被特性及應用做大範圈且有系統的探討,本研究之目的即在於先行探討及了解此一課題,本研究的重點在於發展出一套多時 AVHRR 資料幾何套合的程序。 應用 AVHRR 資料估算植被指數的研究中,影像的幾何校正工作乃是前置作業之一,特別是在套合多時影像之前,必須將影像投影至相同座標系統下,如此才可得出可靠之比對結果。在影像套合工作裡,控制點的尋找是件重要的工作,本研究使用 Landsat 正射影像及標準化互相關係數法(簡稱 NCC) 自動搜尋 AVHRR 資料共輒像點。由於考慮到大氣效應會使得原始可見光或近紅外影像匹配結果不良,因此研究中所採用之匹配影像為 NDVI 影像,因 其可去除大部分的大氣效應對影像匹配的干擾;另外,本研究使用改良式二閾值法做為濾雲方法以減少匹配錯誤。本研究結果顯示:本程序可獲得接近次像元的 AVHRR 多時影像套合精度,這對低解析度的氣象衛星資料而言, 此方法具有相當的實用性。

Abstract

This study is the first part of a research on developing to a practical procedure for estimating NDVI using AVHRR data. In this part (Ⅰ) the focus is on the geometrical registration problem. The registration of multi-temporal AVHRR images is a very important task for the long-term NDVI estimation. Basically the accurate geometrical registration is the base of the future NDVI analysis and monitoring. In this study, we use one referenced orthimage of Landsat TM and NCC matching method to registrate AVHRR images. For avoid the atmospheric effect, the NDVI images estimated with AVHRR are used in the matching step. Meanwhile, the modified 2 threshold values method is used to mask the cloudy pixels. The result shown that the sub-pixel geometrical registration accuracy are gotten, and this producer proposed in this study is practical for low-resolution eteorological satellite images.

關鍵字

AVHRR、 植被指數、 幾何套合

Keywords

AVHRR, Vegetation Index, NVDI

附件檔名

華芸線上圖書館

N / A

備註說明

199903-4-1-1-17

Pages:

19-33

論文名稱

高光譜資料之光譜差異分析及量化指標

Title

The Analysis and Quantification of Spectral Differences for Hyperspectral Data

作者

王儷蓉

Author

Li-Jung Wang

中文摘要

近年來由於高光譜影像掃描器的發展,使得高光譜影像所包含之光譜資訊較多光譜影像來得豐富且精細。理論上,應用含有豐富又精細光譜資訊的高光譜資料,應有助於分辨更細微差異之地物。然而以傳統之統計分類技術應用於高光譜影像時,不僅無法提昇分類之層次與精度,且會產生分類效率慢以及需要大量訓練資料等問題。為了找出問題所在,首先由資料表現觀點論述高光譜資料在不同空間之表示方式及其特性;再從不同表示空間中分析光譜之差異性;最後將光譜差異引伸至類別差異性,利用傳統多光譜類別分離度理論探討高光譜類別分群之方法及其效力。

Abstract

Recently due to the advance of image scanning technology, hyperspectral image scanners which have tens or even hundreds spectral bands have been developed. Comparing to the traditional multispectral images, hyperspectral images have richer and finer spectral information than the images we can obtain before. Theoretically, using hyperspectral images should increase our abilities in classifying land use/cover types. However, when traditional classification technologies are applied to the analyzing processes of hyperspectral images, people are usually disappointed by the consequences of low efficiency, needing a large amount of training data, and barely improvement of classification accuracy. In order to solve this problem, technologies of hypersepctral data analyses and processes must be developed. First, this paper illustrates the characteristics of three different spaces (Image, Spectral and Feature) in which hyperspectral data can be inspected. Then, some fundamental statistical theories and graphical presentations of the statistics for hyperspectral images are introduced. Then, spectral differences are analyzed in difference spaces. In addition to spectral differences, differences between two hyperspectral data classes are also analyzed.

關鍵字

高光譜資料、光譜分析、光譜差異

Keywords

Hyperspectral data, Spectral analysis, Spectral difference

附件檔名

華芸線上圖書館

N / A

備註說明

199903-4-1-19-33

Pages:

35-44

論文名稱

以二維 CAD 數值圖輔助數位影像中屋頂模型之重建

Title

Roof Reconstruction from Digital Images and 2D CAD Information

作者

吳碧玉, 王蜀嘉

Author

Pi-Yu Wu, Shue-Chia Wang

中文摘要

本研究以台南市郊大比例尺航空像片為實驗區,研究了於數位影像中以數值地圖協助邊緣線匹配以重建屋頂幾何模型時應有的做法及問題。研究結果顯示,數值圖主要的協助有兩方面: 一是協助篩選可能的屋頂邊緣線,另一是在邊緣線破碎、缺漏時加以填補成一完整的屋頂。由研究結果也可看出,即使有 CAD 資料的輔助,要正確重建屋頂的模型也不是一件容易的事。最大的原因還是在低階邊緣萃取的結果不理想,常有破碎缺漏或受鄰近較強訊號干擾的情形。但是總體而言,以 CAD 地圖輔助後的成功率是大幅提升了。

Abstract

Automatic building reconstruction by simple edge matching encounters many difficulties. The major one is that most of the edges extracted from an image by a low-level linear feature extraction method do not belong to any building edge at all. Moreover, an edge which appears to be straight in the image might actually not be straight in the object space at all, or it might even be from two totally different edges in the space. All these make simple edge matching ambiguous and very difficult to obtain a correct result. In this paper we used large-scale aerial images of a suburban area of Tainan for experiment and developing the methods of reconstructing roof models by edge matching with the help of digital map data. We found out that digital map data can be helpful in two ways. One is that the maps can be used to narrow down the search area for finding building edges. The other is that they can be used to fill up gaps in a broken image edge or even to complete a missing edge. The results of this research also show that even with the help of map data, it is still not easy to reconstruct roof models completely. The main reasons are (1) the low­level edge extraction is often faulty, (2) the roof edges extracted are usually interfered by adjacent strong signals or are broken, (3) some roof edges could not be extracted at all. But in general, with the help of digital maps, the successful rate of reconstruction of roofs by simple edge matching can be indeed increased effectively.

關鍵字

數位立體影像、數值地圖、屋頂模型重建

Keywords

Digital stereo images, Digital map, Roof-reconstruction

附件檔名

華芸線上圖書館

N / A

備註說明

199903-4-1-35-44

Pages:

45-52

論文名稱

「科技短文」獨立模型中投影中心量測精度探討

Title

On the Accuracy ofProjective Centre Determination for Independent Models

作者

史天元

Author

Tian-Yuan Shih

中文摘要

在獨立模型法空中三角之中,投影中心觀測量的加入對增強幾何結構有極大之功效。本文回顧求取投影中心模型座標的數種方法,並就雙高層法 (Double Z Method) 及解析相對方位法之精度,進行探討。

Abstract

The introduction of projective centre into the block adjustment with independent models can strengthen the geometry and provide much better convergency for the aerotriangulation. In this note, the accuracy of the projective centre determination with two different methods is studied. These two methods are the ΔZ method and the one with analytical relative orientation.

關鍵字

獨立模型、投影中心

Keywords

Independent model, Projective centre determination

附件檔名

華芸線上圖書館

N / A

備註說明

199903-4-1-45-52

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