ENGLISH

5卷/2期

5卷/2期

華藝線上圖書館

Pages:

1-14

論文名稱

高光譜影像特徵萃取方法之探討

Title

Feature Extraction for HyperSpectral Images

作者

徐百輝 , 曾義星

Author

Pai-Hui Hsu , Yi-Hsing Tseng

中文摘要

與傳統多光譜影像比較,高光譜影像提供了更豐富且細緻的光譜資訊,理論上應該可以提升影像分類的精度。然而若將處理多光譜影像的理論及分類方法應用於高光譜影像中,所獲得的成果卻不如預期中理想。首先是高光譜龐大的資料量造成處理效率降低;而在分類精度上,隨著資料維度的增加,卻沒有足夠的訓練樣本數目以提升樣本統計量的估計精度,造成最後的分類精度降低。為了解決高維度資料所帶來的問題,特徵萃取成為高光譜資料分類之前所必須進行的工作。本文綜合整理一些既有的特徵萃取演算法,並從訊號處理的觀點出發提出兩種新的特徵萃取方法。最後對各種特徵萃取方法的結果實際進行分類及比較,期能找出一良好的特徵萃取方法,使得對於高光譜影像分類精度的增進能有所助益。

Abstract

Comparing to the traditional multispectral images, hyperspectral images include richer and finer spectral information than the images we can obtain before. Theoretically, using hyper-spectral images should increase our abilities in classi-fying land use/cover types. However, when traditional classification technologies are applied to process hyperspectral images, people are usually disappointed at the consequences of low efficiency, needing a large amount of training data, and hard improvement of classifica-tion accuracy. In order to solve this problem, our atten-tion in the paper is focused on dimensionality reduction by feature selection or ex-traction. In this paper, we propose two new methods for feature extraction. The Two methods based on Frequency Space are Fourrier Spectrum Feature Extrac-tion and Wavelet Decomposition Feature Extrac-tion. We also compare with other feature extraction methods which have been developed from some other proposed papers. Finally, a practical AVIRIS data are analyzed to illustrate our discovery and test to show the efficiency of the new feature extraction methods.

關鍵字

高光譜影像、特徵萃取、主軸分析、傅立葉轉換、小波轉換

Keywords

Hyperspectral Data, Feature Extraction, Principal Component Transform, Fourier Transform, Wavelet Decomposition

附件檔名

華芸線上圖書館

N / A

備註說明

200006-5-2-1-14

Pages:

15-29

論文名稱

特徵匹配於影像起始套合應用之研究

Title

Initialization for Image Registration Using Feature­ßased Matching

作者

陳良健 , 李政道

Author

Liang-Chien Chen , Jeng-Daw Lee

中文摘要

本研究嘗試利用影像之區塊特徵,藉由各種區塊形狀之描述子,輔以特徵相似性的評估,進行特徵匹配,透過匹配之區塊自動化建立影像間的起始對應關係。一般自影像中萃取出來的區塊其輪廓為高低頻互見,且在自動化考量中高低頻之出現是無法預見的。因此;假設我們所萃取出的區塊包含上述兩種區塊形狀;且同時出現時,我們必須能有效率且迅速正確對於較高頻或低頻的形狀來描述,並且找出能同時考慮互補的形狀描述子。我們在此提出,利用不變的矩(Invariant Moments)、傅立葉描述子(Fourier Descriptors)和形狀矩陣(Shape Matrix)作為描述元,並以此三者做為判斷相似性之指標,同時使用 三種特徵描述的方法描述其形狀之相似性,並建立相似係數矩陣同時測試三個描述子對於不同區塊特徵所反映出之特性。 建立相似係數矩陣後,再藉由一對應篩選法則濾除特徵匹配中錯誤之對應。再由這些正確的對應區塊,以其重心位置為套合控制點,進行起始轉換係數求解,可找出並建立套合影像與參考影像間起始的相對坐標轉換關係。以此為出發點,可提供進一步套合控制點加密時,匹配位置之預估資訊。

Abstract

This investigation uses feature matching which includes feature extraction, region descriptor and similarity assessment to initialize the correspondence for image registration. Shapes of the extracted regions appear to be in high frequency and low frequency in terms of shape irregularity. This irregularity, in general, is not predictable in the feature extraction stage Thus, we consider both possibility and then strive to investigate the suitable matching strategy. We propose three descriptors to characterize the region shapes, namely invariant moments, Fourier descriptors, and shape matrix. According to the matching matrix designed in this study, we screen out the erroneous correspondence. Then for these determined conjugate regions, centroids are used as registration control point in the initial stage. Following a coordinate transformation as prediction, fine matching is applied to generate final registration control point pairs.

關鍵字

不變的矩、傅立葉描述子、形狀矩陣、套合影像、參考影像、特徵匹配

Keywords

Invariant Moments, Fourier Descriptors, Shape Matrix, Sensed Image Reference Image, Feature Matching

附件檔名

華芸線上圖書館

N / A

備註說明

200006-5-2-15-29

Pages:

31-46

論文名稱

以屋頂面法線為約制條件協助立體像對中建物邊緣之篩選

Title

Screening of Building Edgesin Stereo Aerial Images Using Surface Normals as Constraints

作者

陳世崇 , 王蜀嘉

Author

Shih-Chung Chen , Shue-Chia Wang

中文摘要

近年來,隨著資訊科技的進步,空間資訊的展示也從傳統的二維圖紙平面式的表達,進步到三維數值式的方式。舉凡虛擬實境(virtual reality)、數值城市模型(citymodel)都是此方面的應用。而其中人工建物的自動化萃取為其中關鍵性的步驟,亦成為數值攝影測量領域中重要的研究課題。在人工建物的自動化萃取方法中,常是以建物邊緣線的搜尋為出發。但一般在影像上搜尋建物邊緣線的方式,其結果常是過於凌亂與破碎。為了改善此一情形,輔助資料的引入是必須的。而數值表面模型便常被當成輔助資料。 數值表面模型已包含了建物的高程與粗略的表面幾何形狀。如果可以透過一有效的分析處理過程,從數值表面模型中取得建物斷線的近似位置,對建物重建的工作將有實質上的幫助。本研究假設一般的建物屋頂是由簡單的幾何平面所組成,而屬於同一平面上的數值表面模型網格法線其方向應該相似。基於此項假設,本研究利用區域成長法將建物的頂部重建為一近似的平面,用以取得建物斷線的近似位置。 本研究的成果顯示所使用的方法在一些條件成立的情形下,確可為僅由影像灰值變化來尋找建物邊緣線的方式,提供一有參考價值的輔助資料。

Abstract

With the progress of the informative technology, traditional methods of displaying the spatial information on 2D analogue maps have also evolved to 3D display in digital form. Virtual Reality, 3D City Models, etc. are, among others the examples of this evolution. As a result, how to automatically extract the man-made buildings from aerial images becomes a very important research topic in the field of the Digital Photogrammetry. The automatic building extraction always begins with the extraction of gray level edges. But the gray level edges detected by most edge detecting algorithms are often broken or irrelevant to building edges. In order to cope with these problems, other knowledge should be included to assist the search of the building edges. Digital Surface Model (DSM) is one of them. Digital Surface Model is the representation of the surface height information of the terrain, 'including the height information of buildings, trees and other fixed objects standing on the ground. Through proper analysis, approximate roof outline can be detected form the DSM. These outlines can then be used to assist the search of the building edges. In this research we assume that roofs are consisted of simple planar surfaces. Based on this assumption, surface normals which belong to the same planar surface should be have same orientations in the space. Therefore we can use the region growing technique to detect the approximate borders of that plane. The results of this research show that under proper conditions the approximate locations of building edges can be detected. These locations can then be used to screen out gray leve1 edges which do not belong to any buildings.

關鍵字

邊緣線、法線、數值表面模型、區域成長

Keywords

附件檔名

華芸線上圖書館

N / A

備註說明

200006-5-2-31-46

Pages:

47-54

論文名稱

「科技短文」新竹交通大學近景攝影測量檢驗場之設置與評估

Title

The Establishment and Performance Evaluation of the Close-Range Photogrammetric Test Field in National Chiao-Thng University, Hsin-Chu

作者

龔健彬 , 史天元

Author

Chien-Bin Kung , Tian-Yuan Shih

中文摘要

為能提供近景攝影測量應用時相機檢驗之使用,本研究選擇新竹市交通大學光復校區內一建築物之外部設立檢驗場。在其上選取自然點位為控制點。各點位之三維座標以全測站經緯儀量測獲得,各點座標值之精度根據推估應在 lcm以內。本檢驗場同時以量測性地面攝影機Wild P32量測,以前方交會計算各點位之三維座標,以為比較。檢驗場之點位定義以局部影像記錄,並以網際網路網頁之型態提供查詢,以方便各界之使用。

Abstract

A test field consisting of 79 points has been established in the exterior of a building in National Chiao-Tung University, Hsin-Chu. The three dimensional coordinates of these 79 points are measured with a total station. The accuracy of the coordinates is within 1 cm. Al1 these points are chosen from the corner or the intersection of edges. No signalized points were used. A Wild P32 metric camera is used for a photogrammetric evaluation of this test field. A web page is established for documenting this test field. Both the point definition and the coordinates are provided through the net.

關鍵字

Keywords

附件檔名

華芸線上圖書館

N / A

備註說明

200006-5-2-47-54

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