Siril is an image processing software for astronomical CCD imaging, designed for calibration, stacking, alignment, and post-processing of deep-sky images.
HEC-RAS is a free river analysis system from the U.S. Army Corps of Engineers for one- and two-dimensional steady and unsteady flow modeling of rivers and channels.
VizTerra is a powerful 3D landscaping and outdoor living design software that allows users to quickly and easily create 3D models of their ideal outdoor living spaces.