Meshlab open source system for processing and editing 3D triangular meshes, but can also deal with point clouds
CloudCompare open source 3D point cloud and mesh processing software
Open MVS (Multi View Stereo) a library for computer-vision scientists and especially targeted to the Multi-View Stereo reconstruction community.
Open SFM Open Structure From Motion, OpenSfM is a Structure from Motion library written in Python on top of OpenCV. The library serves as a processing pipeline for reconstructing camera poses and 3D scenes from multiple images.
Bundler: is a structure-from-motion (SfM) system for unordered image collections (for instance, images from the Internet) written in C and C++.