臺灣博碩士論文加值系統

本論文之研究目的在於校正水下雷射掃瞄量測系統之CCD攝影機。對於量測水下結構之表面外形尺寸，可利用雷射掃瞄線投射在待測物表面上；當從斜視角觀測時，若待測物表面高度不一，掃瞄線會有斷線或變形的現象。斷線之高低位差愈大表示該區的高度落差愈大。用 CCD 擷取影像後，經過影像處理就可換算斷面之尺寸。
CCD 攝影機在鏡頭周圍會有光學的扭曲，CCD 屏幕的密度也會有不均勻的現象。此外，對於實際應用上，攝影機的3D 位置和方位都會影響到畫面的擷取。所以要用雷射掃瞄線來做斷面尺寸量測時，首先就要將CCD 鏡頭校正過。以往在機器視覺的應用上，CCD 鏡頭的校正都使用一個具有十多個參數的數學方程式來描述攝影機的非線性現象。在本文我們用一塊有50 mm 間隔的網格校正板，並用線性、二次最小平方差及 Cubic Spline 來描述網格，並且借用地球投影製圖的觀念，以內差方式建立圖素座標與幾何座標之關係來達到 CCD 攝影機校正的目的，我們也選擇數種不同尺寸、形狀的物體進行雷射掃瞄量測的實驗，以檢驗 CCD 校正的效果。並進行濁度實驗以瞭解濁度對量測影像之影響。實驗結果顯示這一個方法校正過的 CCD 攝影機在以雷射掃瞄量測時，誤差大致可控制在 3 \% 下。

To estimate the correct dimension of the target on the underwater, we can use CCD camera and cast laser light strip onto the target, and then observe the displacement of laser light to get the dimension. Since the laser light will show on different situation, it''s due to the surface of the target is not smooth. When we get the image from CCD camera, we need to calibrate the displacement of the laser light and return to the actual dimension of the target on the underwater.
We know the optical distortion and non-linearity of the CCD camera will influence to get the correct image, also the location of camera is. That''s the reason we need to calibrate the camera first. It was a mathematical way to explain the calibration of CCD camera non-linearity before.
On this subject, we lay vertical and horizontal grid lines of 50 mm span on an acrylic plate. These grid lines are same as the longitudes and latitudes of the map. We estimate the target with the pair of interpolated longitude and latitude same as to be used to estimate the location of the point in the world coordinate
system. And choose some targets with different size and form to use to verify the approach. By the way, we also test if there is any influence for the clear of water. The results indicate the error is under 3 \% when we catch the image on the underwater by a calibrated CCD camera.

第一章 緒論
第二章 校正原理
第三章 實驗架設
第四章 實驗結果分析
第五章 結語
附錄

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