We collected the on-road data during September 2023 in Rosyth, Queensferry and Penicuik near Edinburgh, Scotland. Foggy data was collected first, and the counterpart clear data in overcast weather was collected two weeks later by traversing the same routes.

Data episodes and sequences

In total, 52 data episodes, consisting of 103 data sequences, were collected. Apart from only one episode (R00, last row of the table below) that contains only a foggy sequence, each of the remaining 51 episodes comprise a foggy sequence and a counterpart clear sequence of the same route. The total duration of the foggy and the clear videos are 2578 seconds and 2443 seconds, respectively.

Further, by visually examining the foggy images, we subjectively classify the 52 foggy sequences into thin fog (20 sequences totalling 1101 seconds) and thick fog (32 sequences totalling 1477 seconds).

In the following table we show the details of each data episode in SDIRF, including the scene, the weather condition, the start time, and the duration. We also show the camera’s gain and the exposure settings of each sequence. For each combination of gain and exposure settings, we conducted a photometric calibration in a controlled environment.

Folder structure of each sequence

The recorded data files of each sequence are organised in a folder that has the following structure.

Xxx_weather
├── images_colour
│   ├── image_0
│   │   ├── 000000.png
│   │   ├── 000001.png
│   │   ├── 000002.png
│   │   └── ...
│   ├── image_1
│   │   ├── 000000.png
│   │   ├── 000001.png
│   │   ├── 000002.png
│   │   └── ...
│   ├── img_timestamps.csv
│   └── img_timestamps_zeroed.csv
├── imu
│   ├── imu_data.csv
│   └── imu_timestamps.csv
└── mag
    ├── mag_data.csv
    └── mag_timestamps.csv

• Xxx is the episode:X represents where the data episode was recorded, and xx represents the number. For example, R00 represents the first episode recorded in Rosyth, Q01 represents the second episode recorded in Queensferry, and P02 represents the third episode recorded in Penicuik.
• weather represents the weather condition: FogThin, FogThick, or Overcast
• image_0 (resp. image_1) is a folder containing the images of the left (resp. right) frame.

Sequence thumbnails

The following table summarises the sequence thumbnails for each episode in the dataset. Each entry shows the representative image for the foggy sequence and, where available, the corresponding overcast sequence.

Episode	Scene	Fog density	Foggy	Overcast
P00	Residential area	Thick
P01	Residential area	Thick
P02	Residential area	Thick
P03	Residential area	Thick
P04	Residential area	Thick
P05	Residential area	Thick
P06	Suburban road, residential area	Thin
P07	Residential area	Thin
P08	Residential area	Thin
P09	Residential area	Thin
P10	Residential area	Thin
P11	Residential area	Thin
P12	Suburban road	Thin
P13	Suburban road	Thin
P14	Suburban road	Thin
P15	Residential area	Thin
P16	Residential area	Thin
P17	Residential area	Thin
P18	Residential area	Thin
P19	Residential area	Thin
P20	Residential area	Thin
P21	Suburban road, residential area	Thin
P22	Residential area	Thin
P23	Residential area	Thin
P24	Residential area	Thin
Q00	Residential area	Thick
Q01	Residential area	Thick
Q02	Residential area	Thick
Q03	Residential area	Thick
Q04	Residential area	Thick
Q05	High street, suburban road	Thick
Q06	Country road	Thick
Q07	Suburban road	Thick
Q08	Suburban road	Thick
Q09	Suburban road, residential area	Thick
Q10	Residential area	Thick
Q11	Residential area	Thick
Q12	Residential area	Thick
Q13	Residential area	Thick
Q14	Residential area	Thick
Q15	Suburban road	Thick
Q16	Residential area	Thick
Q17	Residential area	Thick
Q18	Suburban road	Thick
Q19	Residential area	Thick
Q20	Residential area	Thick
Q21	Residential area	Thick
Q22	Residential area	Thick
Q23	Residential area	Thick
Q24	Residential area	Thick
Q25	Residential area	Thick
R00	Suburban road, country road	Thin		-