現代人對於身體健康與生活舒適度的要求日益提升，尤其每天皆會穿著的鞋子對於一個人的影響甚鉅。然而多數人對於本身足部的形狀與尺寸了解不多，即便經過店員推薦並試穿過，還是時常發生購買到不合身的鞋子。因此有一套非接觸式的掃描器可以擷取足部資訊以便進一步分析是有其必要性。
一套掃描器必須透過相機校正來換算出3D模型並保持整體系統的精度。以往在相機校正領域常見的方式是藉由多張棋盤格影像來進行相機內外部參數校正，也有利用建立一個參照表的查表法。然而多數的方法都需要有一定相關專業知識才有辦法進行操作。因此本研究目的為開發一套適合一般大眾能夠使用的應用於三維足部掃描器的校正方法。
在驗證本研究所提出的校正方法精度上，利用校正後得到的相機外部參數與真實3D點回推2D點座標做誤差分析，距離誤差約為2 Pixel。在驗證重建精度上利用直徑65.5 mm的標準撞球，標準偏差約為0.6 mm。在資料重現性上，同位置多次掃描的標準偏差約為0.1 mm。從以上實驗結果驗證了此論文提出的校正方法的可行性。

Modern people's demands for physical health and comfort are increasing, particularly for shoes. It has a great impact for people who wear shoes every day. However, most people don't know much about the shape and size of their feet. Even following the recommendation of clerks and trying on, the shoes often do not fit after purchasement. Therefore, it is necessary to have a non-contact scanner that can capture foot information for further analysis.
A scanner always needs calibration to calculate the 3D model and maintain the accuracy of itself. In the past, the common method of camera calibration is to perform camera internal and external parameter correction by using multiple checkerboard images or using the look-up table method to establish a reference table. However, most methods require relevant expertise to operate. The purpose of this study is to develop a calibration method for a three-dimensional foot scanner that would be suitable for the general public.
In verifying the accuracy of our proposed calibration method, we analyzed the error by comparison with estimated 2D points and the known 2D points. The re-projection error of our system is about 2 pixels. To verify the reconstruction accuracy, a standard billiard ball with a diameter of 65.5 mm is used. The standard deviation is approximately 0.6 mm.
In terms of data repeatability, the standard deviation of multiple scans at the same location is approximately 0.1 mm. The feasibility of the calibration method proposed in this paper is verified from the above experimental results.

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