本文的主旨是以雷射結構光法對海床表面小尺度粗糙面之量測及重建。結構光需要一個經過校正的~CCD~當成輸入裝置，而水下環境不同於一般的空氣中有較理想的光學特性。所以我們在本文中以一種類似地圖投影經緯線的觀念來進行~CCD~圖素座標系統與測量工程座標系統之間的轉換。因為在~CCD~的鏡頭周圍會有扭曲的光學現象，讓畫面中的物體產生形變。對於這種非線性變化，我們以~CNC~加工機在一塊板面上精確製造出間隔~50mm~的網格點，此板我們稱為校正板。以~CCD~擷取校正板網格點畫面後，利用地圖的製作原理，對於畫面中扭曲的格線以二次最小平方近似多項式描述成如地圖中的經緯線。利用這些經緯線，我們可以轉換在畫面裡目標點的工程座標值。為了驗證系統的性能，我們加工一個已知特性的正弦沙波曲面，以供測量比對。數據分析結果顯示，在約一公尺外的距離進行掃瞄測量，對於振幅~3mm~到~8mm~的變化，測量誤差可以控制在~1mm~以下。為了進一步瞭解系統對不規則曲面的測量性能，我們另外加工一塊以空間頻譜亂數還原測試工件，進行分析。分析結果，在同樣的掃瞄設定下，空間頻譜也可準確至~3~至~5mm~的波數。為了考量實海域的操作條件比較嚴苛，我們自行設計並外包加工製作了一套旋轉式的雷射掃瞄系統。旋轉式掃描設計為自動化的擷取系統，以單板電腦作為控制平台，配合~PLC~來管理系統電源。以~2~個~12V~的鉛蓄電池當電源時，每小時取樣一次，每次擷取~360~個畫面，約可運作~39~個小時。

This paper reports the design and development of an underwater laser scanning system to measure the geometry of underwater objects. The application of structure light scanning method requires a calibrated CCD camera as the input device. Because the underwater environment is by far different from that in the air. Conventional calibration methods adopted in the air can not be applied for the underwater cases. In this paper we propose an algorithm which is analogous to the idea of longitudes/latitude in map projection to calibration the CCD. The calibration board pattern is fabricated by laying vertical and horizontal grid dots of 5cm span with an NC milling machine. To obtain the higher accuracy, we redesign the laser source holder to make the board and laser scan line coplane. We use a new laser that is focus adjustable. So we can capture clearer image of the edge on the target. Then, we calibrate the CCD camera with the calibration board. For testing our new system, two test pieces are used. One is sine waves ripples with varying amplitudes from 8mm to 3 mm. The other one is a rough surface with know spatial power spectrum. Scanning results show that: Scanning from rough 1 meter away, the absolute error for the sine wave ripples is less than 1mm along vertical direction. The power spectrum for the rough surface is accurate to the order of 3 to 5mm wave number. In order to survive in the harsh underwater environment, we design and make a rotational scanning system. The system was designed as an automatic image-capturing system, utilizing single board computer as control plane to work in conjunction with PLC(Programmable Logic Controller) for System power management. When using two 12V batteries as main power source, obtaining samples once per hour, capturing 360 images per operation, the system may run for approximately 39 hours.

第一章 緒論……………………………………………………………1
1.1前言…………………………………………………………………1
1.2文獻回顧……………………………………………………………1
1.3研究目的……………………………………………………………4
第二章 結構光量測法…………………………………………………6
2.1經緯線格點校正法…………………………………………………7
2.2轉換範例……………………………………………………………9
2.3網格控制點的搜尋方式……………………………………………12
2.4經緯線擬合…………………………………………………………13
第三章 掃描系統設計…………………………………………………14
3.1系統運作流程………………………………………………………14
3.2水密傳動軸與水密箱………………………………………………15
3.3可程式邏輯控制器…………………………………………………18
3.4影像擷取控制程式…………………………………………………18
3.5雷射光源架設調整…………………………………………………19
第四章 人工海床設計與加工…………………………………………22
4.1海床表面資料來源…………………………………………………22
4.2外型粗加工…………………………………………………………23
4.3表面精加工…………………………………………………………25
第五章 誤差分析與結果討論…………………………………………29
5.1架設參數估算………………………………………………………29
5.2雷射線影像探討……………………………………………………34
5.3量測結果……………………………………………………………39
第六章 結果與討論……………………………………………………41
6.1討論…………………………………………………………………41
6.2結語…………………………………………………………………42

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