Seafloor images and raw context data along AUV track SO239_28-1_AUV3 (Abyss_169) during SONNE cruise SO239

The raw images (available on request) have been captured using a Canon 8-15mm fisheye lens and therefore they have a wide field of view, which results in a dark image boundary as the lights did not illuminate the outer sectors well. The images in this dataset have then been undistorted to virtual images that an ideal perspective camera with only 90 degrees horizontal field of view would have seen from the same position. To achieve this, the color of each pixel in the ideal image is obtained by
- computing the ray in space associated with this virtual pixel (using rectilinear un-projection)
- projecting this ray into the original fisheye image (using equidistant projection), yielding a sub-pixel position
- interpolating the colors of the neighboring pixels
Technically, the undistortion has been performed using the tool https://svn.geomar.de/dsm-general/trunk/src/BIAS/Tools/biasproject.cpp (at revision 418, and earlier, compatible revisions).
Manual image annotation is available here: https://annotate.geomar.de/volumes/227

本数据集的原始图像（可应要求提供）采用佳能8-15mm鱼眼镜头拍摄，因此具备宽视场特性。由于灯光无法良好照亮图像边缘区域，最终采集的图像存在边界偏暗的问题。
本数据集内的图像均已完成畸变校正，转换为仅具备90°水平视场角的理想透视相机在同一拍摄位置所能采集到的虚拟图像。为实现该转换，理想图像中每个像素的色彩通过以下步骤获取：
- 计算该虚拟像素对应的空间光线（采用直线反投影法）
- 将该光线投影至原始鱼眼图像（采用等距投影法），得到亚像素坐标位置
- 对邻域像素的色彩进行插值运算
从技术层面而言，本次畸变校正操作使用了工具 https://svn.geomar.de/dsm-general/trunk/src/BIAS/Tools/biasproject.cpp（采用修订版418及更早的兼容修订版本）。
人工图像标注数据可通过以下链接获取：https://annotate.geomar.de/volumes/227