This dataset contains the data used and collected to investigate the reliability of avalanche size estimates and avalanche outlines (see related publications). Namely this is #### Avalanche size estimates #### * the 10 pictures depicting avalanches * the survey results from the 170 participants #### Avalanche outlines mapped from oblique photographs #### * the pictures of the six avalanches * the avalanche outlines mapped by the 10 participants * the reference mapped from the georeferenced photographs #### Avalanche outlines from remotely-sensed imagery #### * the orthophotos in the four different resolutions (2m, 1m, 50cm, 25cm) * the area of interest (AoI) delimiting the research area * the avalanche mappings in each resolution for all five participants * the shade masks used to separate illuminated and shaded areas The acquisition of the orthophotos has been partially supported by the Swiss National Science Foundation (SNF; Grant N°200021_172800).