Abstract: In order to explore effective methods for determining the fire origin through video light and shadow analysis, this paper selects typical cases of fire video light and shadow analysis, extracts the principles of general light and shadow analysis models such as symmetric reflection, three-dimensional occlusion, and geometric calculation of light and shadow dividing lines. A real-scene verification experiment is designed, and its effectiveness in determining the fire origin is verified by combining with real cases. A three-dimensional reconstruction light and shadow analysis simulation experiment is designed. Unreal Engine 5 is used to perform three-dimensional reconstruction of the fire scene, and simulation tests are carried out by using the model auxiliary line method or the simulated light source position trial-and-error method to verify its effectiveness in determining the fire origin. The study can provide practical reference for grass-roots fire investigators, helping to improve the efficiency and accuracy of fire investigation.

Key words: video light and shadow analysis, 3D reconstruction, fire origin, fire investigation