Because squares and rectangles are the main shape of a photograph, they’re not the shapes that your viewers will notice.
So triangles (and similar) need to be used to invite your audience to see all of your photograph. This technique is also used by abstract, surreal and cubism (oddly enough) painters, plus many record-album-covers of the 1980’s. Or did only I notice that?
So triangles are the building-block of a successful photograph.
The structure of your photograph should have three sides: The APEX is either the point at which you are, or the eventual subject within. The sides are those diagonals (train-tracks, perspective, roads, repeated subjects, etc ), verticals (walls, trees, arms, etc), horizontals (oceans, city-scapes, hills, etc) of your image. Each form an integral element that form the basis of any image.
Thus ends the short series explaining how geometric lines are the basis for good photography. And you thought photography was just art not academia!
Yet the series does not end here…