Cast shadows estimation and synthesis using the Walsh transform

• Shadow synthesis using Walsh transform.
• Fast cast shadow estimation of 3D surfaces.
• Shadow estimation based on orthogonal base functions of WT.
• Experiments were performed with 3D data to verify the theory.

Cast shadow estimation and synthesis remains an open research topic both for computer vision and computer graphics applications. There remains scope for faster and more robust estimation techniques. Walsh transforms have traditionally being neglected due to its sensitivity to the input signal’s phase. However, the orthogonal nature of its base functions makes it ideal for cast shadow estimation. In this paper it is proven that the Walsh transform can be successfully used for shadow casting, by proposing a new algorithm. Furthermore, experiments were performed to validate the proposed methodology and indicate further applications.