ellipse in perspective critique

ahtiandr

Hi all!

I have started learning perspective and I really need you advice!
I got the book called "How to Draw" by Scott Robertson and in that book author explains how to draw ellipses in perspective. So I got my perspective grid in photoshop and decided to draw some ellipses.

First I start by drawing an ellipse with predefined angle (60) by using Lazy Nazumi photoshop plugin . Next I add horizontal tangent lines which go to the right vanishing point. Next I connect tangents of the ellpse with a vertical line and its degree is 93,48. Next I add same vertical line to both ends of the ellipse and I get my square in perspective. Everything is looking good so far. Next I place same square into a perspective closer to the left vp and I try to place second ellipse into that square but for some reason it just doesnt match. No matter what angle I try it just doesnt fit in. There is always some mismatch.

Now I try to do same thing again but this time I start with vertical line set to 90 degrees and horizontal lines pointing to the right vp. Next I fit the ellipse inside and add another vertical line to close the square. Then again the far ellipse doesnt match in the same square in perspective

Finally I decide to build my perspective grid from few lines and an ellipse. First I add one vertical 90 degrees and two horizontal lines. Next I fit the ellipse and add another vertical to close the square. Then I extend the lines into perspective and find my right and left vanishing points. Next I add same square into perspective and add another ellipse inside it. Everything matches correctly and I get pretty good degree variations.

So it looks like I can build a perspective grid from an ellipse but I cant fit an ellipse in predefined perspective grid and this is bothering me a lot. I hope you can help me to resolve this struggle and sorry for so big and boring question.

Greg Westphal

I'm a bit confused by what you said so I just went through and tried to draw everything I remember from my draw through classes (not taught by Scott, but by his students.)  One thing I noticed is that your first two actually look way better than the one you said you were able to draw the perspective grid off of the ellipse.  That grid is actually the furthest away from having the ellipses fit.  

If this doesn't help then let me know and when I finish traveling I'll dig out my Robertson books and figure out whats going on.  Also, forgive the shit freehand, I just woke up. 

ahtiandr

Oh thats so nice of you! But looking at your guide I am a bit lost at how you ensure that the square in perspective is still square. I mean when you distort it you can make its height different to its length which makes it no square anymore. Here is an example of what I am trying to say:


Also I am not sure if it is correct to have vertical line of the square not perpendicular to the horizon line like on the first pictures I have posted?

Greg Westphal

The answer to your second question as to if the vertical line has to be perpendicular to the horizon line, yes, if it is in 2 point perspective and following that grid.  However, if you're drawing in in 3(+) point perspective then you're vertical lines will converge and if its 5point they will round.  Also, keep in mind that your over all camera can by locked to a 2 point perspective grid, but the objects themselves might be rotated in ways that won't have their lines converge cleanly with just that grid.

The answer to your first part is a bit rougher.  Scott teaches in the book how to construct a perfect cube I think, but, the caveat is almost no one does that amount of work unless absolutely necessary.  Keep in mind that your eye cannot see in true 2 point perspective because the lens of your eye will warp stuff as it nears the edges of your periphery.  Truthfully, you're always looking at stuff in 5 point.   There are rules on how to make a cube spatially perfect in 2 point, but just like how I showed you in the example that there is the correct method of drawing a circle, giving you 12 contact points to draw your line through and the one I use only gives 4, thats kind of how everyone approaches cubes.  If you follow Scott's books on how to draw cubes a few times, it'll give you the to understanding of what it should look like well enough to eyeball it in practice at least well enough to trick someone into believing its perfect.   

https://www.youtube.com/watch?v=uYNBEFJeo-A this is a youtube video from a guy I follow who talks about how to draw a perfect cube in 2 point.  It takes him roughly 17 minutes to get it done, so you can see why most people, after its done a few times, can't be bothered.

ahtiandr

Thanks a lot again!

I know Sycra of course! He is a very cool teacher but  apparently missed this video. Now I see it is not fun at all to do this sort of staff. Actually I tried myself to copy an x-wing concept art but from different angle and it took me about one week to make just the base construction and it was quite boring.  Anyway, I think I know what was wrong with my first drawing of the ellipse. I was using predefined grid and I tried to fit an ellipse with a specific angle (60 degree) which is wrong because my grid should dictate what ellipse I can fit. So either I make an ellipse with specific angle and build a grid out of that or I construct grid and then I fit the ellipse inside it.

RN

I disagree with some things in that Sycra video, like right at the start he picks two points on the horizon line to begin drawing.
It suggests it's an arbitrary decision, but it's not, there's a way to select perfect points that give the object rotation you want: you rotate the plan view of the object around its anchor point, with the anchor point placed on the viewpoint formed by the visual cone.
http://handprint.com/HP/WCL/perspect3.html#rotatingvp

EDIT: There's a way to prove that it works, you can find vanishing points on the horizon line for whatever vertical rotation of an object that you want.