Whitebox GAT is really a full-blown open-access GIS and remote sensing software package. It actually replaced Terrain Analysis System (TAS) – a tool for hydro-geomorphic applications. There’s a hydrology theme around Whitebox GAT. Unbelievably, Whitebox GAT has only been around since 2009 because it feels so fine-tuned when you see it in action. Yes, Whitebox GAT (Geospatial Analysis Toolbox) is #4 on the list of open source, free GIS software.
