SCARM - Simple Computer Aided Railway Modeller
Regard3D - Regard3D is a free, multiplatform, open-source structure-from-motion application.
TrainCad - Freeware Microsoft Windows program for designing model railroad layouts using standard tracks.
Pix4Dmapper - Photogrammetry software for professional drone-based mapping, purely from images.
AnyRail - AnyRail makes model railroad design so easy, it's fun!
ContextCapture - Acute3D develops breakthrough photogrammetry software solutions to automatically turn photos into photorealistic high resolution 3D models