ENGLISH

11卷/4期

11卷/4期

華藝線上圖書館

Pages:

339-359

論文名稱

萃取物表角面特徵點供多測站地面光達點雲面之連結

Title

Extracting Corner Points for Registration of Terrestrial Multi-Station LIDAR Scanned Surfaces

作者

蔡展榮,李姝儀

Author

Jaan-Rong Tsay,Shu-Yi Lee

中文摘要

本文提出一個半自動化的多測站地面光達點雲面連結方法,它是從雷射點雲萃取被掃瞄物表面上的局部角面特徵點並求定其三維坐標,進而將這些共軛角面特徵點做為連結點,把多個光達測站點雲轉換到同一個物空間坐標系統中,俾行資料連結整合之用。而在實務上,會有角面特徵點品質不佳、點數少、或分佈不佳的情況,所以本文以加入適當的「虛擬角點」的構想來解決此一問題;本文實驗成果顯示,在前述的情況下,加入適當的虛擬角點可改善連結點的幾何分佈強度,使得整體坐標轉換參數精度可提升36%~71%。掃瞄距離S大於50m 時,局部平面點雲到最小二乘擬合平面的距離均方根值RMSD 和S 之比值RMSD/S約收斂於常數0.00015。

Abstract

Terrestrial laser scanner can rapidly acquire accurate and dense 3D point clouds covering the surfaces of scanned objects such as buildings. The point clouds provide the detailed data necessary for accurate building modeling. In order to acquire complete data points on a scanned building, the scanning operations must be done at more stations. Each station has its own coordinate system representing the 3D position of each laser point. Therefore, all coordinate systems of different laser scanning stations must be transformed into a common system to register laser points acquired on different LIDAR stations. This paper proposes a semi-automatic method for registration of terrestrial laser point sets acquired on different stations. Firstly, a point cloud on a local plane is selected manually, and then a mathematical plane is fitted in a least squares manner onto them. Three local planes on an object corner are thus respectively determined, and their intersection point is computed by solving these three plane equations. Such points are used as tie points for transforming different laser coordinate systems into a common one. The transformation is bad in cases of inaccurate, or insufficient, or worse-distributed tie points. This paper suggests to apply suitable “virtual corner points” to solve this problem. The test results show that suitable virtual corner points really can strengthen the geometrical configuration for the transformation and thus raise the accuracy of corresponding transformation parameters with the improvement rate of 36% to 71%. On the other hand, the ratio of the RMSD-value to the scanning distance S≥50m becomes a constant of 0.00015 in case of ,Swhere RMSD denotes the root mean square value of the perpendicular distance from a laser point to its corresponding plane.

關鍵字

光達、最小二乘擬合、角面特徵點、連結點、坐標系統

Keywords

LIDAR, least squares fitting, corner feature point, tie point, coordinate system

附件檔名

華芸線上圖書館

N / A

備註說明

200612-11-4-339-359

Pages:

361-380

論文名稱

結合光達資料與大比例尺向量圖重建三維建物模型

Title

Fusion of LIDAR Data and Large-Scale Vector Map for Building Reconstruction

作者

陳良健,郭志奕

Author

Liang-Chien Chen,Chih-Yi Kuo

中文摘要

數碼城市日益重要。而在數碼城市中,建物為其必要單元。光達資料(LIDAR data)的引進,為自動化建物重建之研究方向帶來可能性。大比例尺向量圖具有精確之二維屋緣線,而光達資料具有豐富之屋頂面資訊。故本研究欲結合以上兩種資料之優勢,進行三維建物重建。本研究工作流程主要分為三部分:(1)資料整合、(2)建物頂共面分析、及(3)建物模塑。在資料整合部分,內容為兩資料之前處理,光達資料需去除地表起伏,而向量圖需建構封閉多邊型。在建物頂共面分析部分,以區塊成長法進行牆面和屋頂面之偵測。最後在建物模塑部分,內容為求取建物三維結構線段,利用SMS法建立結構線位相關係並模塑建物屋頂面高度。本研究並以台中大坑進行測試。光達資料點密度約1.71(點/平方公尺),向量圖比例尺為1:1000,重建完全正確率約90%,模塑誤差為0.17m。

Abstract

Cyber city is getting important. Building models, among others, could be the most important elements in a cyber city. Due to its maturity, LIDAR data has demonstrated profound potentials in fully automatic building reconstruction. LIDAR data contains plenty of height information, while vector maps preserve accurate building boundaries. From the viewpoint of data fusion, we strive to integrate two data to perform building modeling. The proposed scheme comprises three major steps: (1)preprocessing of LIDAR data and vector maps, (2)segmentation and detection of wall and roof faces, and (3)building modeling. In the preprocessing stage, the height variation of the above-ground objects is determined by subtracting the surface elevation from the terrain. The closed polygons for buildings are also obtained. In next stage, segmentation and detection of wall and roof faces is implemented by region growing. In the step of the building modeling, the construct edges of a building could be obtained. Then the 2D topology of building edges is obtained by SMS method. Finally, building models are reconstructed. The test data covers Tai-Chung city in Taiwan. The average density of LIDAR data is about 1.71 points per square meter. The vector maps are with a scale of 1:1,000. About 90% buildings are correctly reconstructed by the proposed method. The shaping error is about 0.17m.

關鍵字

光達資料、向量圖、三維建物重建、迪式三角網

Keywords

LIDAR, Vector Maps, Building Reconstruction, Triangulated Irregular Network

附件檔名

華芸線上圖書館

N / A

備註說明

200612-11-4-361-380

Pages:

381-402

論文名稱

空載三線式掃描儀影像立體定位之研究

Title

3-D Positioning for Airborne Three-line-scanner Imagery

作者

陳良健,林士哲

Author

Liang-Chien CHEN,Shih-Che LIN

中文摘要

空載三線式掃描儀具有較高的空間和光譜解析力,且影像具有良好之幾何交會條件,可為環境遙測、立體定位之資料來源。由於飛行中可拍攝三個方向影像,其成像具有高重疊的特性。在本研究中加入附加參數計算影像像坐標,外方位參數使用時間的多項式進行密合,並使用光束法完成方位求解,最後並使用最小二乘過濾法修正系統誤差。測試資料共包含六個航帶,使用每一航帶之三張不同拍攝方向影像之影像連結點,並加入航帶之間的航帶連結點進行求解。實驗結果顯示以多航帶光束法求解方位,並加入交叉之航帶後,可提升整體精度。

Abstract

Airborne three-line-scanner images have the merits of high spatial and spectral resolutions and excellent converging geometry. Thus, the images have become an important data source in environmental remote sensing and three dimensional positioning. The three-line-scanner acquires three different direction images, which have plenty of overlapped area in flying. Thus, the bundle adjustment is selected to calculate the dynamic orientation parameters. To compensate for the systematic errors, additional parameters are included in the adjustment. The orientation parameters are modeled using low-order polynomials with respect to time by employing GCPs and tie points. The process might contain local systematic errors for the data with high dynamics, thus, a least squares filtering that performs orbit collocation is included. The test data include six strips. In the bundle adjustment, the tie points are selected for each of the three-look images that appear in the overlapped area of strips. The experimental results indicate that the bundle adjustment could reach higher accuracy when the cross strips are employed.

關鍵字

三線掃描儀、光束法、最小二乘過濾、ADS 40

Keywords

Three-Line-Scanner, bundle adjustment, Least Squares Filtering, ADS 40

附件檔名

華芸線上圖書館

N / A

備註說明

200612-11-4-381-402

Pages:

403-415

論文名稱

運用影像分塊方法於高解析衛星影像土地利用判釋精度之研究

Title

The Study on Classification Accuracy of Landuse Categories from High Resolution Satellite Images Using Image Segmentation Algorithm

作者

李瑞陽,莊佳文

Author

Re-Yang Lee,Chia-Wen Chuang

中文摘要

在全面性土地利用調查研究中,以人力調查的方式,既耗時又不符合效益,若利用遙測影像進行自動化土地利用判釋,其正確率又無法滿足實務上需求。因在判釋上,傳統多採單一像元為基礎之影像分類演算法,但此法並未考慮相鄰像元間光譜反應的關係,因此無法準確判釋地物類別。在影像判釋中,為了克服上述光譜分類問題,透過對影像進行分塊(Segmentation),可得到較有意義的資訊。所以本研究於判釋衛星影像土地利用類別時,將運用分塊方法,來彌補他人方法上的不足,而分塊方法考量了灰階值、區塊大小以及相鄰影像之相關性,並引入兩種自動決定分塊門檻之方法,再撰寫程式萃取分塊資訊,經實證後,加入適合度法之分塊門檻成果,於後續判釋中,其分類整體準確度為84%,證明影像分塊確實可應用於土地利用判釋上。

Abstract

In the research of land-use information survey and monitoring broad and simultaneously, traditional land surveying methods, such as field surveys, are time-consuming and costly. In the past, per-pixel classification algorithms were used for research, which did not consider about the location of pixel within the image and the relationship between its spectral response and neighborhoods. So, it can’t classify land use categories accurately. So, in this research on classification of land use categories from high resolution satellite images, we will use a segmentation method to improve image classification accuracy and make up the shortage on the other methods. In this method, on the one hand we considered three factors of gray level, pixel size, and the relationship between neighbor images, and on the other hand we use two automatic threshold selections for segmentation. Therefore, in this research, we utilized image segmentation to improve the classification results of land use categories from QuickBird satellite images. Then, we composed the program to extract the information in the image space for the application of practice. Finally, we obtained good image classification accuracy (overall = 84 percent; Kappa coefficient =0.81) by using degree of fitting threshold selection for segmentation in QuickBird satellite images and segmented image automatically.

關鍵字

影像分塊、高解析衛星影像、土地利用

Keywords

Image Segmentation, High Resolution Satellite Image, Landuse Categories

附件檔名

華芸線上圖書館

N / A

備註說明

200612-11-4-403-415

Pages:

417-426

論文名稱

以曲率為基礎的多邊形縮編技術

Title

Shape-Based Generalization Technique for Polygon GIS Data

作者

陳敏新,陳繼藩

Author

Min-Hsin Chen,Chi-Farn Chen

中文摘要

地圖縮編在地理資訊系統的資料前處理中是一個重要的工具,其中多邊形圖形的縮編是較為複雜的。由於大部分的多邊形縮編方法,是將多邊形簡化成多邊線後,利用線性的縮編方法進行縮編;此時,將多邊形簡化為多邊線的起始點的決定,將會影響縮編後的結果。本研究主要是利用曲率的特性,來進行多邊形圖形的縮編。首先先計算多邊形上每個節點的曲率值,利用曲率即可找出多邊形上較明顯的特徵節點。透過特徵點,就可以將一個封閉的多邊形分割為數個彎曲的線段,此時再對各個線段進行縮編。在本研究中是利用縮編前後面積的變化率,來調整縮編的程度;其中較低的面積變化容忍率,將會保留較多的節點。最後本研究與Douglas-Peucker的縮編結果進行比較,實驗的結果顯示,所提出的方法在使用相近的節點數下,縮編後的圖形相較於原始圖形具有較少的變形。

Abstract

Cartographic generalization represents the process of simplifying a graphic object by reducing the number of its data points. The graphic reduction technique is capable of removing points on a smooth-curve segment, while retaining sharp turning points. Therefore, a good generalization algorithm is not only capable of simplifying data points, but it also retains the similarity of the generalized curve to the original one as close as possible. Among many generalization procedures, polygon shape generalization is considered the most complicated. Since most polygon generalization methods simplify the polygon as poly-lines, therefore the generalized result is significantly affected by the decision of the starting point, which is required in initiating the poly-line generalization algorithm. The purpose of this study is to develop a curvature-based generalization approach for polygon GIS data. Because the curvature can be used to quantitatively measure the shape of a curve, therefore, this approach uses curvature as a generalization index. According to the curvature property, this study classifies the data point of polygon into two types: the critical points and the secondary points. The critical points are the points with relatively large curvature (often with sharp angles) and can be detected automatically by using a curvature threshold. Then the critical points will be used to divide the closed polygon into the curve segments, which can be employed to extract the secondary points. The extraction of the secondary points is performed by ranking the significance of the data points on the curve segments. The significance of the data point will be decided by the curvature and its relative positions to other data points. The data points with larger curvatures and longer distances to neighbor points will have higher chance to be selected as the secondary points, because after simplification, they will not change the shape of the polygon largely. An experiment is performed to compare the proposed method with the Douglas-Peucker method. The test shows that the generalization results of the proposed method have fewer shape distortions, and it can be used to provide an efficient and automatic tool for polygon GIS data generalization.

關鍵字

地圖縮編、多邊形、曲率

Keywords

Generalization, Polygon, GIS Data

附件檔名

華芸線上圖書館

N / A

備註說明

200612-11-4-417-426

Pages:

427-438

論文名稱

福衛二號影像糾正及誤差探討

Title

The Rectification and Error Investigation on the Formosat-2 Satellite Image

作者

廖揚清,蔡文龍

Author

Yang-cheng Liao,Wen-Lung Tsai

中文摘要

本研究使用有理函數模式對福衛二號衛星影像進行計算,另外,由於高階有理函數模式的法方程式需要使用一微小常數h 以穩定計算,因此先討論h值的影響,最後再分析與檢驗殘差。本研究使用台南市的福衛二號影像,其影像的等級為Level1A,影像大小為12000像元×16800像元。首先以分區測試以及不同分佈和數量的地控點進行測試,再改變每一次計算時的微小常數h,以得到最佳的h值。實驗分析顯示,使用周邊分布最少的7個地控點進行計算,檢核點E方向均方根值約±1.50像元、N方向均方根值約±1.75像元;二階的有理函數模式可以得到h值的建議值為0.0002,三階得到的h值的建議值為0.00045。最後,使用顯著水平α=5%進行統計測試,並無檢驗出系統性誤差的存在。

Abstract

The study uses Rational Function Model(RFM) to perform the correction for the Formosat-2 image,because it must use a minute constant h to stabilize the computation of normal equation at high degree RFM,this research would investigate the effect of h value;finally,it would also check and analyze the residual. The test area of Formosat-2 image is Tainan, image level is Level 1A,image size is 12000pixel×16800pixel.The research would use different areas and different number of ground control points with different distribution to test, and change the constant h when every test to get the best constant h. The experimental analysis demonstrated,when uses at least 7 peripheral distributed GCPs to compute, the RMSEe of check point is ±1.50(pixel) and RMSEn is ±1.75(pixel).The proposed h value for second degree RFM and third degree RFM are 0.0002 and 0.00045 .Eventually,the result of t-test doesn’t demonstrate systematic residuals ,when α=5%.

關鍵字

福衛二號影像、影像糾正、有理函數模式

Keywords

Formosat-2 Image、Image Rectification、Rational Function Model

附件檔名

華芸線上圖書館

N / A

備註說明

200612-11-4-427-438

Pages:

439-446

論文名稱

應用改良式Watershed 技術進行高解析衛星影像影像分割

Title

A Modified Watershed Technique for Segmentation OF High Resolution Satellite Images

作者

張立雨,陳繼藩

Author

L. Y. Chang,C. F. Chen

中文摘要

應用Watershed技術進行影像分割在影像處理上是一種常用的方法,然而此法在使用上仍須配合適當之影像勻化處理程序來降低影像複雜度以避免影像過度分割之結果。事實上,若此勻化處理程序之選擇不適當時,不但會造成影像細部資訊之損失並且會降低所偵測出之特徵精確度。為了改善這些缺點,本文根據特徵邊緣過濾技術來改良傳統Watershed影像分割法並應用於高解析衛星影像之分割。在本文中分別應用QuickBird以及IKONOS兩個資源衛星之多光譜與全色態影像來進行測試,在測試結果中可發現本文所提之方法可針對不同之影像特徵產生合理之影像分割結果。

Abstract

Watershed segmentation is a widely used technique for image partitioning. However, over-segmentation normally occurs when the smoothing process is not operated properly. For example, improper selection of smoothing scheme and parameters will not only wipe out the detail of image content but also affect the accuracy of following feature extraction. In order to overcome these drawbacks, a modified watershed segmentation method based on the edge intensity filtering is proposed. An experiment using both QuickBird multi-spectral and panchromatic images is performed to test the proposed scheme. The result shows that the proposed scheme can generate reasonable and simplified segmentation output for different type of objects.

關鍵字

高解析衛星影像, 影像分割, 邊緣強度過濾

Keywords

High Resolution Satellite Images, Image Segmentation, Edge Intensity Filtering

附件檔名

華芸線上圖書館

N / A

備註說明

200612-11-4-439-446

Pages:

447-459

論文名稱

SRTM/TOPSAR 高程數據比對

Title

Comparison of DEM Acquired by SRTM and TOPSAR

作者

賴子銘,史天元

Author

Zi-Ming Lai,Tian-Yuan Shih

中文摘要

本研究針對兩組合成孔徑干涉雷達(Interferometric Synthetic Aperture Radar, InSAR)所產製的數值高程模型(Digital Elevation Model, DEM),分別為太空梭雷達製圖任務(Shuttle Radar Topographic Mission, SRTM)與空載地形合成孔徑雷達(Topographic Synthetic Aperture Radar, TOPSAR),分析兩組高程數據的系統誤差、精度與粗差。比對結果顯示在多山地區SRTM 精度為9.5公尺,在平坦地區精度可達7.6公尺,均優於NASA公佈的精度規範。而TOPSAR在平坦地區精度為8.7公尺,在山區則包含大量粗差。若不經過粗差偵測和編修,無法達到NASA公佈的1~5公尺精度。經初步粗差移除後,平坦地區的精度為5.6公尺,山區則為12.4公尺。

Abstract

This study focused on the DEM comparison for two InSAR DEM data. One is the Shuttle Radar Topographic Mission (SRTM) 3 arc data, and the other is Topographic Synthetic Aperture Radar (TOPSAR) data. The DEM produced with airborne photogrammetry is used to validate the system bias, random error and blunders of those InSAR DEMs. The accuracy of SRTM data is 9.5m in the mountainous area and 7.6m in the flat area, based on the evaluation conducted. It is better than the official specification. But the TOPSAR data that contained massive blunders was not as good as the system specification for either the flat or mountainous area. The results show that the unedited TOPSAR data is hard to achieve the nominal accuracy of 1~5m. After removing the blunders, the standard deviation of DEM difference is about 5.6m in the flat area and 12.4m in the mountainous area.

關鍵字

干涉合成孔徑雷達、數值高程模型

Keywords

Interferometric Synthetic Aperture Radar, InSAR, Digital Elevation Model, DEM

附件檔名

華芸線上圖書館

N / A

備註說明

200612-11-4-447-459

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