I've been reading this page many times and I am still having trouble understanding it. I highlighted the part I can't understand. Can someone please explain it to me?
What exactly is it you don't understand?
I think the part just describes how you can make out the horizon in a picture/painting/whatever... even if it's not actually depicted. Just extend some of the most prominant lines (for example, like it says in the text, of windows and doors etc.) and the point they meet in (sometimes outside the actual picture) is your horizon. This horizon then defines the viewers (and artists) position and all elements in a picture should be portrayed according to this position...
Hope this helps!
regards, Elian : )
@Elian and in2eternity Wow thanks a lot, you save me a lot of trouble from having to ponder about this continuously