Seafloor images and raw context data along AUV track SO242/1_25-1_AUV03 (Abyss_189) during SONNE cruise SO242/1

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/257

本数据集的原始图像（可按需获取）采用佳能（Canon）8-15mm鱼眼镜头拍摄，因此具备宽广的视场角。由于灯光无法充分照亮画面外缘区域，最终成像呈现出较暗的图像边界。
本数据集内的图像已完成畸变校正，转换为等效于仅具备90°水平视场角的理想透视相机从同一拍摄位置所捕捉的虚拟透视图像。该畸变校正流程具体如下：
1. 计算与该虚拟像素对应的空间光线，采用直线反投影（rectilinear un-projection）方法；
2. 将该光线投影至原始鱼眼图像中，使用等距投影（equidistant projection）模型得到亚像素位置；
3. 对相邻像素的颜色值进行插值运算。
技术层面，本次畸变校正通过工具https://svn.geomar.de/dsm-general/trunk/src/BIAS/Tools/biasproject.cpp完成（对应版本418及更早的兼容版本）。
手动图像标注数据可通过以下链接获取：https://annotate.geomar.de/volumes/257