Iterative geometric triangle transformations

SEIMCHA: a new semantic image CAPTCHA using geometric transformations

As protection of web applications are getting more and more important every day, CAPTCHAs are facing booming attention both by users and designers. Nowadays, it is well accepted that using visual concepts enhance security and usability of CAPTCHAs. There exist few major different ideas for designing image CAPTCHAs. Some methods apply a set of modifications such as rotations to the original imag...

Rigid Geometric Transformations

The special case for θ = π/2 radians is known as Pythagoras’ theorem. The definitions that follow focus on three-dimensional space. Two-dimensional geometry can be derived as a special case when the third coordinate of every point is set to zero. A Cartesian reference system for three-dimensional space is a point in space called the origin and three mutually perpendicular, directed lines though...

Geometric Representations and Transformations

Advancing Front Quadrilateral Meshing Using Triangle Transformations

Quad-morphing is a new technique used for generating quadrilaterals from an existing triangle mesh. Beginning with an initial triangulation, triangles are systematically transformed and combined. An advancing front method is used to determine the order of transformations. An all-quadrilateral mesh containing elements aligned with the area boundaries with few irregular internal nodes can be gene...

Human Face Detection Using Geometric Triangle Relationship

The proposed system consists of two main parts. The first part is to search the potential face regions that are gotten from the triangles based on the rules of “the combination of two eves and one mouth”. The second part of the proposed system is to perform the face verijication task. The proposed face detection system can locate multiple faces embedded in complicated backgrounds. Moreover, it ...