When capturing panoramas, people tend to align their cameras with the vertical axis, i.e., the direction of gravity. Moreover, modern devices, such as smartphones and tablets, are equipped with an IMU (Inertial Measurement Unit) that can measure the gravity vector accurately. Using this prior, the y-axes of the cameras can be aligned or assumed to be already aligned, reducing their relative orientation to 1-DOF (degree of freedom). Exploiting this assumption, we propose new minimal solutions to panoramic image stitching of images taken by cameras with coinciding optical centers, i.e., undergoing pure rotation. We consider four practical camera configurations, assuming unknown fixed or varying focal length with or without radial distortion. The solvers are tested both on synthetic scenes and on more than 500k real image pairs from the Sun360 dataset and from scenes captured by us using two smartphones equipped with IMUs. It is shown, that they outperform the state-of-the-art both in terms of accuracy and processing time.

翻译：在捕捉全景时,人们倾向于将其相机与垂直轴,即重力方向对齐。此外,智能手机和平板电脑等现代设备都配备了能够准确测量引力矢量的IMU(内空测量单位)设备。使用之前,相机的Y轴可以对齐或假定已经对齐,将相对方向降低到1-DOF(自由度) 。利用这一假设,我们提出了新的最起码的解决方案,以对相机拍摄的图像进行全景式缝合,即进行纯旋转。我们考虑四种实用的相机配置,假设固定或不同焦距,无论是否进行辐射扭曲。解析器在合成场和Sun360数据集的500多张真实图像配对上,以及从我们所拍摄的场上,使用两台配有IMU的智能手机进行测试。我们发现,在精确度和处理时间上,它们都超过了最新水平。