Surfaces and 3D regions are represented by a triangulated irregular network (TIN) - that is, a network of triangles joined at their vertices. The size and number of these triangles will determine some key performance characteristics:
The resolution of the scene.
Larger triangles make for a coarse scene, smaller triangles for finer scene.
The memory required to store the scene.
The TIN is stored in the EV file. The more triangles, the more space is required, the larger the EV file.
The processing power/time required to render the scene.
The TIN is rendered on the screen in 3 dimensional perspective. The more triangles, the more power or time will be required to affect this rendering.
The resolution of the resampled surfaces is defined independently in two directions (north-south and east-west).