What about diagonals? Let's learn the Sliding Grid method (with a video tutorial).

In the previous post we went through the usual ad-hoc method for drawing equirectangular perspectives. It is a pretty simple method as far as it goes; you just print out an equirectangular grid and draw over the horizontal and vertical lines, like this:  You can go pretty far with that, but you are also very limited. First of all, you don't really know where that grid comes for. Following a grid made by others is not knowing perspective, it is avoiding knowing it. But well, perhaps you're not the sort of fellow that worries about such things, and that's fine too. But there is a more practical problem. Horizontals and verticals are only a small subset of all lines. What about all the diagonals? For instance, what is the shape of the diagonals lines that join opposing vertices of a wall? Those are pretty important as crossing them allow you to find the center of the wall. At the moment we have no way of finding these, as they are not one of our printed lines. But we ne

What is a VR panorama anyway - Tutorial zero

What is a spherical perspective anyway, and how does it relate to a VR panorama? Figure 1 below is an example of a spherical perspective: Fig 1. Spherical perspective drawing. Graphite on A4 tracing paper. I did it from an observation sketch ("urban sketching") on an A4 sheet of tracing paper, at the ISEL engineering school in Lisbon, Portugal (careful shading was later finished at home). You see the drawing is somehow "deformed". You can sort of guess that all these curved lines represent straight lines in space, and that the scene represents a corridor going from left to right. You can see things that are to your left, right, front, back, above and below. In fact, what you get in exchange for the deformation of the lines is that you can fit in this drawing the complete visual information of the scene, as seen by an observer that is in a fixed point in space, but can rotate his gaze freely. The proof that this is so, is that a computer can read this dra

Purpose of this Blog

This blog intends to be an evolving tutorial on how to hand-draw spherical perspectives and VR panoramas. I have written a couple of papers (*) on this subject, but these are far too mathematical for the average artist/urban sketcher, so the purpose of this blog is to make it simple without  dumbing it down . Artists are not dumb and they are not well served by teaching methods that hide the complexity of things. What is needed is time and a careful use of language. Also, the reader's patience, but that's not my part of the deal. Here is my strategy: because I am too busy (teach, research, draw, live!) for long posts, I'll make this fragmentary, and, over time, I'll edit it into a coherent whole. Further, I'll start very simple and I'll refine it as we go along, by revisiting each subject and explaining it in ever more detail: spiraling up! Let's see if this works! First: What is a VR panorama anyway? ----------------------------------------------