行動裝置內建相機之內方位及內建定位定向感測器精度分析

Accuracy Analysis on Built-in Camera’s Interior Orientation and Sensors’ Geo-referencing of Portable Devices

近年來智慧型行動裝置的發展迅速，智慧型手機、平板電腦越來越普及，裝置內建的相機解析度也日益提升，尤其內建了全球導航衛星系統（Global Navigation Satellite System, GNSS）、陀螺儀（Gyroscope）、加速度計（Accelerator）等微機電晶片後，其方便性更甚於一般數位相機。然而行動裝置內建相機之內方位參數穩定度有待檢驗，感測器所提供之位置與姿態，是否足以作為拍攝影像之直接地理定位定向（Direct Georeferencing）亦有待評估。因此本研究將參考前人使用非量測性數位相機進行近景攝影測量的研究成果及理論基礎，以實做方式分析使用行動裝置應用於近景攝影測量之內、外方位參數精度。本研究項目有二：（1）裝置相機內方位之穩定性：本研究針對同一型號四台平板，以及使用同一台行動裝置重複拍攝率定標，分別利用iWitness Pro軟體進行相機率定，以評估同一型號裝置與同一台裝置之內方位參數是否穩定。（2）行動裝置內建定位定向感測器之精度：本研究針對同一型號四台平板之GNSS坐標以及姿態角進行精度分析，同時與e-GNSS作比較，以評估平板電腦之外方位參數是否穩定。 Smart portable devices developed rapidly in recent years. Tablets and smartphones are more common for people. The resolution of the camera in these devices is also rising. In particular, after built-in GNSS, gyroscopes, accelerometers and other MEMS sensors, the device is more convenient than general digital cameras. However, the stability of the interior orientation parameters of the built-in camera has to be tested. The position and attitude provided by the built-in sensor, is sufficient as a direct geo-referencing of the shooting images, also yet to be assessed. Therefore, this study will be based on former research results about non-metric digital camera used in close-range photogrammetry. We will design experiments to explore the accuracy of interior and exterior orientation. This study has two issues. First, the interior orientation stability of the portable devices: we will repeat shooting the coded calibration targets by the same model four tablets and by a single tablet. Then we get interior orientation parameters by camera calibration in iWitness Pro. Second, the accuracy of GNSS and gyroscopes in portable devices: We analyze the precision of GNSS and attitude by the same model four tablets, then compared with e-GNSS.

Smart portable devices developed rapidly in recent years. Tablets and smartphones are more common for people. The resolution of the camera in these devices is also rising. In particular, after built-in GNSS, gyroscopes, accelerometers and other MEMS sensors, the device is more convenient than general digital cameras. However, the stability of the interior orientation parameters of the built-in camera has to be tested. The position and attitude provided by the built-in sensor, is sufficient as a direct geo-referencing of the shooting images, also yet to be assessed. Therefore, this study will be based on former research results about non-metric digital camera used in close-range photogrammetry. We will design experiments to explore the accuracy of interior and exterior orientation. This study has two issues. First, the interior orientation stability of the portable devices: we will repeat shooting the coded calibration targets by the same model four tablets and by a single tablet. Then we get interior orientation parameters by camera calibration in iWitness Pro. Second, the accuracy of GNSS and gyroscopes in portable devices: We analyze the precision of GNSS and attitude by the same model four tablets, then compared with e-GNSS.