SDF

SDF is an acronym that can refer to several different concepts across fields, including mathematics and computer graphics, chemistry, geopolitics, and national defense.

Signed distance function. In mathematics and computer graphics, a signed distance function assigns to every point in space the shortest distance to a given surface, with the sign indicating whether the point lies inside or outside the shape. SDFs are used to render implicit surfaces, perform collision detection, and support constructive solid geometry through techniques such as ray marching and voxel representations.

Structure-data file. In chemistry, SDF denotes a structure-data file format used to store multiple molecular structures and associated data fields. Developed by MDL Information Systems, SDF files (often with the .sdf extension) contain atom and bond information and can include additional data fields. They are widely used for exchanging chemical information and for database storage in cheminformatics workflows.

Syrian Democratic Forces. In Middle Eastern geopolitics, SDF refers to the Syrian Democratic Forces, a multi-ethnic alliance formed around 2015 to combat ISIS in Syria. The force includes Kurdish, Arab, Assyrian, and other groups and has operated with coalition support, achieving territorial control in parts of northern Syria and influencing local governance structures there.

Self-Defense Forces. In Japan, SDF stands for the Self-Defense Forces, the unified armed forces established after World War II and operating under a pacifist constitution. The structure comprises the Ground Self-Defense Force, Maritime Self-Defense Force, and Air Self-Defense Force, and its roles include national defense, disaster response, and international peacekeeping.