ENGLISH

8卷/2期

8卷/2期

華藝線上圖書館

Pages:

1-11

論文名稱

高解析力衛星影像控制點之自動化萃取

Title

Automated Extraction of Control Points for High Spatial Resolution Satellite Images

作者

林乘逸;陳繼藩

Author

Cheng-Yi Lin;Chi-Farn Chen

中文摘要

進行衛星影像的幾何校正通常需控制點,常用的控制點選取方式是以人為的方法比對影像與地圖,將影像中的明顯特徵物選取出來,然後在地圖上找到對應點的座標當成控制點。高解析力衛星影像,如一公尺解析力的IKONOS全色態影像,具明顯的影像特徵相當多,因此極具控制點選取自動化的潛力。本文主要目的是研究高解析力衛星影像控制點自動化選取的方法,控制點以道路交口之影像特徵為研究目標。研究方法以數位影像處理為基礎,其步驟可分為二大部分,第一部份為道路萃取,第二部分則為道路交點搜尋。測試結果顯示本研究方法可有效地自動選取控制點,達到衛星影像控制點自動化萃取之實用性。

Abstract

As IKONOS satellite with 1-m resolution has been lunched in 1999, mapping using space-borne images will be a hot issue in computer vision area and photogrammetry. It is obvious that one of the great challenges to process the high spatial resolution satellite images will be the geometric correction practice. Conventionally, the positioning of the image control points is manually performed by a labor-intensive and time-consuming procedure. Furthermore, due to the abundant image contents, high spatial resolution satellite image would have plenty of the qualified control points. As a result, the manual identification and positioning of control points will become even more inefficient and unbearable. Therefore, the main objective of this study proposes to develop an automated image processing technique to extract the control points for the high spatial resolution satellite images. Among numerous spatial features, this study considers even widespread road intersection the main target to perform the control point extraction. The proposed method consists of two parts. The first part is "road extraction" consisting of four steps image-processing algorithm and the second part is "road intersection searching" consisting of two steps image-processing algorithm. A series of high spatial resolution satellite images are used to test the proposed method. The results shows that the oposed image processing approach has the potential to automatically position the control points in the high spatial resolution satellite image.

關鍵字

高解析力衛星影像,控制點自動化萃取,道路

Keywords

High Resolution Satellite Image,Road Intersection,Control Points

附件檔名

華芸線上圖書館

N / A

備註說明

200306-8-2-1-11

Pages:

13-36

論文名稱

利用Landsat TM資料以Maha I anobis影像分類法分析德基水庫之藻華現象

Title

Analysis of Algal Bloom in Techi Reservoir Using Mahalanobis Classification Method with Landsat TM Data

作者

章國威;吳啟甫;陳伯中

Author

Kuo-Wei Chang;Chi-Nan Wu;Pei-Chung Chen

中文摘要

本文以經鏡檢所得之二角多甲藻的數量為地真(Ground Trulth)資料,並依此地真資料來選取訓練區(Training Region),再以Mahalanobis監督式影像分類法(SuPervised Image Analysis),來分析德基水庫二角多甲藻(Peridinium bipes stein fa.occlatum)之藻華區域。所得之藻華影像分析圖與地真調查之結果相近,其皆顯示藻華發生之區域多位於水庫上游區域,且藻華發生之區域及面積會隨季節變化而有所不同。究其原因發現,水庫上游集水區為梨山溫帶水果及高麗菜的主要產區,大量的營養鹽隨著山坡土壤的沖蝕而流入水庫上游,因而提供二角多甲藻大量繁殖之良好環境。此外,由於蔬果之施肥期及其施肥量會隨作物之生長期的不同而有所不同;故造成沖蝕流入水庫之營養鹽量會隨著季節的不同而有差異,因此使得藻華發生之區域面積會隨季節變化而有所不同。以監督式影像分類法分析德基水庫之藻華區域,不但可以同時獲得整體之水體資料,又可以同一分析方法分析不同時期之水體資料,來消除可能之人為誤差,故此法不失為藻華監測之有利工具。

Abstract

We used the observed dinoflagellate densities as ground truth data and selected the training regions with the ground truth data then analyzed the dinoflagellate (Peridinium bipes) algal bloom areas in the Techi reservoir using mahalanobis classification method. The results of Mahalanobis classified images and ground truth data are similar. They all showed that algal bloom areas most located on the upstream of the Techi reservoir. The algal bloom sites and areas varied with seasons because many agricultural activities on the upstream of Techi reservoir and fertilizers ran off to the reservoir which provided a good environment for the growth of Peridinium bipes. The reason why the algal bloom site and areas varied with seasons is because that the fertilized period and fertilized quantities varied with the different growth period of vegetation, and as the results, fertilized quantities ran off to the reservoir varied with different seasons. In conclusion, Mahalanobis classification method is a powerful tool for monitoring algal blooms, by getting entire water body data and temporal water body data simultaneously.

關鍵字

德基水庫,二角多甲藻,藻華,遙測, Mahalanobis監督式影像分類

Keywords

Techi Reservoir,Dinoflagellate,Algal Bloom,Remote Sensing,Mahalanobis Classification Method

附件檔名

華芸線上圖書館

N / A

備註說明

200306-8-2-13-26

Pages:

27-54

論文名稱

估計GPS接收機L1/L2差分延遲之研究

Title

Study on GPS Receiver L1/L2 Differential Delay Estimation

作者

林老生

Author

Lao-Sheng Lin

中文摘要

由於GPS人造衛星與接收機硬體上的限制因素,產生所謂的人造衛星L1/L2差分延遲(BS),與接收機L1/L2差分延遲(BR)等系統誤差。每一顆GPS人造衛星的BS,與每一部接收機的BR皆不同。因此,如果欲以GPS觀測量求得無偏差之電離層TEC估值,必須事先估算各GPS人造衛星的BS與接收機之BR。本文研究的目的是針對台灣地區的電離層TEC變化狀況,提出一種演算法,用以估算各GPS測站之接收機Ll/L2差分延遲(BR)。至於人造衛星L1/L2差分延遲(BS)部份,則採用美國JPL(Jet Propulsion Laboratory)所估算的結果。有關接收機的Ll/L2差分延遲(BR)演算法的基本原理、估計步驟,以及實驗結果將於本文加以介紹。根據初步實驗結果顯示:(I)利用國立政治大學兩個GPS測站(CUAI、CUA2)在不同時期所收集的資料,以試驗本文所提出的方法:(1)以2000年資料估計CUA2的BR為6.21ns,以2002年資料估計CUA1及CUA2的BR分別為4.73ns與5.67ns。(2)以本文所提演算法所估計的BR與JPL估算的BS總和(SPR),改正CUA2測站於2002年3月3日收集的GPS資料所估算的TEC,求得當天垂直TEC(VTEC)的最大與最小值,分別為60.7ns與2.7ns。(3)CUA1與CUA2平距約77公尺,取2002年3月3日收集的GPS資料,以各站之SPR,分別改正兩測站資料估算的TEC,然後,針對每一顆衛星、每一曆元,分析比較此兩測站對同一顆衛星的VTEC較差△VTEC(上標 k)cua2-cua1,所有△VTEC(上標 k)cua2-cua1的平均值為0.34ns,中誤差為0.10ns。(Ⅱ)以PGGA的CRFP站資料所估計的SPR(上標 k)值為測試對象。首先,假設CRFP 對各人造衛星之SPR(上標 k)為真值。其次,用本文所提出的演算法,估計各人造衛星之SPR估值(SPR)。最後,計算SPR(上標 k)與SPR的較差(△(上標 k)SPR)。實驗結果顯示,所有△(上標 k)SPR的平均值為0.13ns,中誤差為0.98n。

Abstract

One of the challenging problems in making absolute ionospheric delay measurements using the dual-frequency observations to the GPS satellites is to estimate satellite L1/L2 differential delay (BS) and receiver Ll/L2 differential delay (BR). In this paper an algorithm is proposed which can estimate the receiver L1/L2 differential delay (BR) of any static GPS site. Then, the accumulated values of the estimated BR and the satellite L1/L2 differential delays (BSs) estimated by JPL, SPRs, are used to correct those GPS derived TEC estimates. The estimation method and preliminary test results are described here. GPS Data from sites CUA1 and CUA2, National Chengchi University, Taipei, Taiwan were used to test the proposed algorithm. The test results indicate that: (1) The estimated receiver L1/L2 differential delays of CUA1 and CUA2 are 4.73 ns and 5.67 ns respectively using year 2002 data. (2) The maximum and minimum VTEC values observed at site CUA2 on 2002/03/03 are 60.7 ns and 2.7 ns respectively, after applying estimated SPR corrections. (3) The mean value and standard deviation of the VTEC differences to those common GPS satellites from sites CUA1 and CUA2, on 2002/03/03, are 0.34 ns and 0.10 ns respectively. (4) The mean value and standard deviation of the differences between the observed SPR and the estimated SPR using the proposed algorithm of site CRFP, PGGA, are 0.13 ns and 0.98 ns respectively.

關鍵字

全球定位系統,電離層,全電子含量,接收機L1/L2差分延遲之研究

Keywords

Global Positioning System (GPS),Ionosphere,Total Electron Content (TEC),Receiver L1/L2 Differential Delay

附件檔名

華芸線上圖書館

N / A

備註說明

200306-8-2-27-54

Pages:

55-68

論文名稱

氣球載具數值航空攝影測量

Title

Digital Photogrammetry Using Tethered Balloon

作者

黃灝雄;林士淵

Author

Hao-Hsiung Huang;Shih-Yuan Lin

中文摘要

設計一種機動有效的蒐集空中攝影影像為本研究之主要動機,因此設計了以氣球為載具,裝載數位攝影機之航空攝影方式。載具中包含電視(CCD)攝影機與數位攝影機,前者用來監視攝影地區,可即時無線傳輸影像,呈現於地面之LCD監視螢幕上。地面線控之氣球升空後,經由監視螢幕,得知CCD與數位兩台攝影機之視場,故可調整氣球並移動至預定之攝影位置,在預定攝影地區呈現於LCD螢幕時,即遙控啟動數位攝影機之快門裝置。成像經過正射糾正鑲嵌後,與其他現有地圖影像資料一同用來分析與比較,評估檢核點之後,得知成像可達次像元之精度,而與現有1/1000比例尺之數值地形圖比較,亦可見對位情況良好,本研究所採用之航空攝影方式,對小地區之大比例尺製圖而言,確為可行且有效之方式。本研究曾選定一段小流域面積之河川實驗區,利用分類後比較方式偵測研究區之變遷,分類圖與伴隨之自至(from-to)資訊明顯表露河川實驗區在不同時期之變遷情況。

Abstract

Using a flexible and efficient way to obtain aerial images has been the primary purpose of this study. The balloon platform was used to take aerial images. A video camera and a digital camera were fixed together in a durable plastic box, and hung on the balloon. The video camera was used to monitor the ground view, and its image could be telemetered remotely and displayed on a LCD monitor arranged on the ground. Once monitoring the area of interest shown on the LCD, the shutter button of the digital camera was then pushed remotely and the interested image was taken. The resultant images were ortho-rectified for analysis and comparison. The accuracy of aerial images was examined by check points. The results showed that the images achieved sub-pixel accuracy and were well-matched with the 1/1000 digital topographic maps. This expressed that it was really a useful and efficient method of taking large-scale images for a small research area. At last, post-classification comparison method was introduced to detect change of the ortho-rectified images which were taken in three different periods. The classification maps and the from-to change class information clearly indicated the change of river way among various periods.

關鍵字

氣球載具,數值攝影測量

Keywords

Balloon Platform,Digital Photogrammetry

附件檔名

華芸線上圖書館

N / A

備註說明

200306-8-2-55-68

Pages:

69-80

論文名稱

「科技短文」立體鏡式桌上型數位攝影測量系統之地形製圖評估

Title

The Evaluation of Mapping Accuracy with Mirror-Based Digital Photogrammetric System

作者

趙錫民;謝嘉聲;史天元

Author

Hsi-Min Chao;Chia-Sheng Hsieh;Tian-Yuan Shih

中文摘要

使用桌上型個人電腦為主機之數位立體製圖儀,有數種形成立體視覺之方法。本研究以一桌上型數位攝影測量系統,採用外掛立體鏡,觀測分割螢幕,進行內外方位、立體繪圖等數位攝影測量作業模式,探討該系統之人機界面、視覺環境。測試區為台南市東區虎尾寮附近地區之立體航照像對及地面控制點,最後以立體觀測重新檢測控制點座標。初步評估一般航測作業人員應可達兩像元之平面位置較差,與四個像元之高程較差,足敷數位攝影測量實習。

Abstract

For a digital stereo mapping system, there are several different methods to obtain stereoscopic vision. A photogrammetric system based on a desktop personal computer and a mount-on mirror stereoscope is utilized and evaluated for its functionality and mapping environment in this study. It is found that this system can provide basic mapping functions such as handling interior, relative, and absolute orientations, and maintains the perspective relation of the stereo-pair during the mapping process. Mapping accuracy to less than 2 pixels in XY-plane and 4 pixels in height can be achieved for plain operators.

關鍵字

立體觀測,數值地形模型,數值航測

Keywords

Stereoscopic Viewing,Digital Elevation Model,Digital

附件檔名

華芸線上圖書館

N / A

備註說明

200306-8-2-69-80

Pages:

81-92

論文名稱

「科技短文」開發以視窗為基礎之遙測影像大氣改正資訊系統

Title

Development of a Window-based Atmospheric Correction Information System for Remotely Sensed Data

作者

劉建慧;林峻鋒

Author

Chien-Hui Liu;Jun-Fong Lin

中文摘要

由於光學遙測感測器所截獲之訊息乃始於地面之反射與放射,而這些物理量均受大氣所吸收及散射,因此使用原始灰度值遙測影像資料建置之任何模式,均無法應用於預測。為了遙測真實地面反射率,應用大氣改正模式消除大氣效應是必須的。但由於此模式輸入參數眾多,為了快速處理多時遙測影像以因應國土監測,本研究著重於開發以視窗為基礎之大氣改正資訊系統。此大氣改正資訊系統,具備圖形介面模組及BACM衛星影像處理模組。其優點為具備操作友善、自動化讀取大氣改正所需參數、簡易影像顯示及增揚功能且BACM可與圖形介面模組完全分離以利模式精度改進時系統之更新。以SPOT HRV衛星影像反演地表反射率為例,BACM目前精度在有限之地面光譜輻射儀量測資料配合下,結果指出經大氣改正後水稻反射率之RMSE由改正前之0.089減少為0.04;NDVI由大氣改正前之0.418減少為改正後之0.164,此顯示BACM能有效減少大氣效應之影響。雖然如此,本研究也就此系統之限制及未來須加強之部分加以討論。

Abstract

Any model built by the raw remote sensing data cannot be used for prediction, since the signal, which is reflected or thermally emitted from the surface, received by the sensor is absorbed or scattered by the atmosphere. Therefore, it's indispensable that raw image be corrected for atmospheric effect for the purpose of remotely sensing surface reflectance. In order to quickly process multi-temporal data for land-cover monitoring, we develop a window-based atmospheric correction information system for remotely sensed data, since the model requires too many parameters for input. The atmospheric correction information system includes both modules of graphic user interface and BACM satellite image processing. Its advantages include user friendly GUI, automation of input of parameters for atmospheric correction, simple functions of image display and enhancement and independence of BACM with GUI module for convenience of updating improved model. By using the limited data measured by spectroradiometer, the results show that RMSE of rice reflectance has been reduced from 0.089 to 0.04 and that of NDVI has been also reduced from 0.418 to 0.164 after atmospheric correction for case study of using SPOT HRV image to retrieve surface reflectance. Hence, BACM can effectively reduce the atmospheric effect of remotely sensed data. Nevertheless, limitations and future approaches of improvement of the system have also been discussed.

關鍵字

大氣改正模式,視窗,遙鋇,反射率

Keywords

atmospheric correction model,window,remote sensing,reflectance

附件檔名

華芸線上圖書館

N / A

備註說明

200306-8-2-81-92

更多活動學刊