UUU.1.3.3 Computing The Area of A Region of Interest
Prev | UUU.1.3 Introduction to 2D to 3D Map For Wide Field Ophthalmic Photography | Next

### UUU.1.3.3 Computing The Area of A Region of Interest

Let R be the region of interest on the 2D image and it is tessellated by set of unit triangles T={Ti}. By unit triangle we refer to isosceles right triangle that the two equal sides have one pixel distance (4-connected neighbors). The area of the region of interest can be computed as the sum of partial areas of the unit triangles in 3D. Let { ai , bi , ci } be the 3D coordinates of the three points of unit triangle Ti . The 3D area of this triangle is

and the total area of R is:

Where (‖ … ‖) and ( x ) refer to the magnitude and cross product, respectively.

Consider that ai , bi and ci are the 3D coordinates not the 2D indices of the unit triangle points on the image.

Prev | Up | Next
UUU.1.3.2 Shortest Distance Between Two Points | Home | UUU.1.3.4 Transformation Method Code Sequence