animation (version 0.2-0)

vi.grid.illusion: Visual Illusions: Scintillating grid illusion and Hermann grid illusion

Description

A grid illusion is any kind of grid that deceives a person's vision. The two most common types of grid illusions are Hermann grid illusions and Scintillating grid illusions. This function provides illustrations for both illusions.

Usage

vi.grid.illusion(nrow = 8, ncol = 8, lwd = 8, cex = 3, 
    col = "darkgray", type = c("s", "h"))

Arguments

nrow

number of rows for the grid

ncol

number of columns for the grid

lwd

line width for grid lines

cex

magnification for points in Scintillating grid illusions

col

color for grid lines

type

type of illusions: 's' for Scintillating grid illusions and 'h' for Hermann grid illusions

Value

• None.

Details

This is actually a static image; pay attention to the intersections of the grid and there seems to be some moving points (non-existent in fact).

References

http://en.wikipedia.org/wiki/Grid_illusion

See Also

points, abline

Examples

# default to be Scintillating grid illusions 
vi.grid.illusion()

# set wider lines to see Hermann grid illusions 
vi.grid.illusion(type = "h", lwd = 22, nrow = 5, ncol = 5, 
    col = "white")