You'll be using Sketch 1 of this file which has three different types of triangles - scalene, isosceles, equilateral. Each triangle type has a different colour (pink for scalene, red for equilateral, ...

This paper focuses on the study of 2D calibration method, involving a new planar pattern based on equilateral triangles, and a new camera calibration algorithm using the new pattern. Firstly, three ...

Its key unit is the ‘grid cell’, which is activated whenever the animal's position coincides with any vertex of a regular grid of equilateral triangles spanning the surface of the environment.