Regard3D is a free and open-source photogrammetry software that uses the structure from motion (SfM) method to generate 3D models.
Although Regard3D is free, it is still a very powerful piece of software. Indeed, it may take you a while to settle in and get comfortable with all the settings and parameters you can adjust before you achieve the kind of results you want. The program even includes comprehensive tools for editing the point cloud before generating a 3D mesh. If you are new to photogrammetry software, this is a great place to begin: Regard3D’s website offers all the guides and tutorials you need to get started quickly.