Perspective Tomfoolery part 2

I mentioned in my last post that the previous example did not cover the axis on the top and bottom of the page. If you ignore the convergence coming from the Z axis (up and down), you might draw things in perspective like this:

  What would the world look like if the z axis didn’t visually converge onto vanishing points as the X and Y axis do? Duke Nukem 3D, and many other early 3d videogames, answers this question. Due to the nature of primitive corridor shooters, and the technical limitations of a 1996 home computer, the z axis in such games were not programmed to converge. I found two screen-shots showing this quirk off for those of you who haven’t seen it before:

 You may recognize this nuance in other media. For example, for a long time, photographers have used special lenses (and Photoshop filters) to ‘correct’ the perspective on buildings:

 I’ve included the uncropped version so you can see how much artificial distortion is happening to the picture. Here’s the original:

For arguments sake, what is the perspective in this shot really doing? Or rather, what would be an accurate way to simulate the perspective converging east to west and up and down at the same time? That’s where 5-point perspective comes in:

 Here’s a building drawn on top so you can see this in application. In most scenarios, you would most likely want to crop in so the distortion around the edges is lessened:

 Understandably, you might not want to use this in every one of your layouts/projects. We usually abstract this into ruler-made three-point perspective, if z axis distortion is required. When do you know you should be using it? The further up or down you’re looking, the more likely you should be introducing a third vanishing point. This chart I made demonstrates:

 Coincidentally, this also explains, as a guideline, how to fib two-point perspective if you don’t want to warp it like with the last post I made. Just flip the chart on its side and you’ve got shorthand for the other axis. Something I found useful is not even plotting distant vanishing points at all- just eyeball two slightly converging lines on either side of the horizon line and interpolate some lines in between. That way you don’t have to use a two metre long piece of paper to plot some awful vanishing point far away from your centre of interest.

Again, I hope someone out there has found this informative!