The Point File In TOP will read point data from various mesh and floating point data files including: .obj , .ply , .fits (astronomy format), and .exr . It can also load ASCII point files (.xyz , .pts , .csv , .txt , etc) with one point per line and comma or space separated fields.
You can make use of Cloudcompare to load .e57 files and export the pointcloud(s) in a supported format (mostly the ASCII point file formats).