**M****ore about h/d,
presentation of angles**

Focusing on a square by a defined angel alpha (h/d = tan alpha) allows to estimate the ratio of the "visual" heights (v) to the "visual" length (w) of a square as v/w = h cos alpha/d. Figure 1 shows a graph for a grid of h/d = 0.2, figure 2 for a grid of d/h = 0.4.

Images 1, 2 and 3 are photo-presentation of a square-grid. Measured values v/w for the squares a,b,c,d were about 10 % higher than calculated values, most likely reflecting problems associated to the lens of the camera. For artistic purposes, a difference of 10 % in v/w is mostly irrelevant. However depending on the request a careful evaluation of the way the image is created may be mandatory.

Image 3 : **Using a square-grid is a valuable method for an
appropriated presentation of angles. **