Basic Photography Lessons, The Golden Triangle Rule
This rule is useful if the scene is composed of many diagonal lines. The Golden Triangle Rule is a practical spin-off of the Diagonal Rule where three triangles are formed from the reference diagonal line in the Diagonal Rule.
First, a guide is made by drawing a line from one corner of the screen to the opposite corner, similar to the diagonal guide we use in the Diagonal Rule. From this line draw perpindicular lines towards the other remaining corners, all in all forming four similarly shaped triangles, 2 large triangles, and 2 small triangles. Aligning the lines in your scene to these guide lines while positioning your subject on any of the intersections will make your photograph aesthetically pleasing. The alignment doesn't have to be precise and the elements in your scene doesn't have to be straight, just enough that it is distinguishable.
In certain scenes it may also be possible to use the same guide that we created here to divide your scene into three significant sections. Pick any three of the four triangular areas and position your scene such that the three imaginary sections fall into one of these triangles.
This method gives your picture some sense of organization and gives each imaginary sections a sense of priority as to which is the most significant. The eyes are naturally drawn first to the largest triangle then to the mid-sized triangle and lastly to the smallest.
In this sample picture, the first thing that you would naturally focus on first are the concrete wave breakers on the bottom right portion and probably the tall building on the upper right. Then, you would look at all the street view on the left. The rest of the image above with the skies and mountains and far away buildings would probably get the least attention.
Put your mouse over the sample image to see how I imagined the Golden Triangle is positioned in this picture, although it is highly subjective and your view may be totally different. The important thing to note is the how this rule may be applied.