Thats a perspective trick I didn't know! Thanks.

this is interesting, but i can't tell what the purpose is. does this exercise have an academic name? thanks.

It's basically the start to a perspective grid. But this is also flexible for other things like proportions and making an array of objects. If there's an academic term I'm not aware of it, but I do know a resource that uses it is Scott Robertson's "How to Draw".

i've seen perspective grids before, but i can't work out how to use this. then again, my background is primarily life drawing, so my training was probably a lot different. still, thanks for responding.

I guess I'm also confused by the question of what it's supposed to be used for? Because intuitively my answer is "everything". To me it's not just about what specific thing I can do with this technique, but what mastering the technique can give me. In this case, it's a means of honing a spatial imagination; the ability to project a 3D space on a 2D plane. It's a fundamental principle to the point where even if I'm not using it I'm "using it". I think every artist should try to build that kind of intuition, and for me the best way to start seemed to be with this basic grid construction.

I'm not sure if that answered anything, I'm not an especially good teacher. But I'm always happy to clarify anything.

i believe you that it's a perspective tool; my struggle is in /how/ to use it because its function is not obvious to me.

rereading these comments and staring at it for a few minutes more is giving me an idea, though: is it a grid on a plane with a single vanishing point? kind of like if you took graph paper and had all the lines going away from you converge off in the distance?

Fun addendum for anyone who reads the comments: The distance between VP and VP' represents a field of view and can be used to simulate lens distortion. Typically this means that you want VP' well beyond the bounds of the image, but you can also play around with it for fun different effects. As VP' comes close to the inside of the image it creates a "fish eye" effect. This can be compounded if you run another vanishing line through VP.

Ahhh, I should do a fish eye grid tutorial now that I think about it.

Share more of your wisdom with us, sensei.