# Thread: Draw a perfect square using two vanishing points

1. Registered User Level 1 Gladiator: Andabatae
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## Draw a perfect square using two vanishing points

Hi, I have two vanishing points and a rectangle in a perspective, now I would like to draw a perfect square in the rectangle. How can I do?

Thank you!

2. Registered User Level 1 Gladiator: Andabatae
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I'm sorry but this doesn't seem to work. Example:

3. Registered User Level 1 Gladiator: Andabatae
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Those vps are intersections between rectangle sides computed by a software.

4. Jester Level 7 Gladiator: Samnite
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Originally Posted by Anid Maro
Drew up a rough example.

Attachment 1468123
Basically in the red is what you should already have, as you had described it.

Take that bottom corner, farthest from the horizon (drawn between the two vps), and draw a straight line perpendicular to the horizon.

Where that new line intersects the edge of the rectangle opposite of the bottom corner, that's where you draw out your square.
No. Construct your vanishing points from your stationary point, and construct the vanishing point of the diagonal from there. In other words: RTFM

5. Anid, those verticals will have to converge as well.

6. Registered User Level 1 Gladiator: Andabatae
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Mhhh... I would like to draw the square inside the rectangle... Can't I bisect a corner or something similar?

7. Other way.

8. Registered User Level 1 Gladiator: Andabatae
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Ok, who can explain other ways to do this?

9. how do you determine if the third vp is up or down?

10. Jester Level 7 Gladiator: Samnite
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Originally Posted by Anid Maro
Put it this way, if the third vp is such that as you go farther back shapes get larger then it needs to be the other way. Such as in my earlier mistake.

Another way to put it, place the third vp above the horizon.
No. The question is about constructing squares in perspective. This does not involve a third vanishing point for verticals.

Let me take the freedom to explain what Elwell was trying to say; I beg him to forgive me if he was trying something else. The construction lines that are vertical in your two-dimensional drawing go through the diagonals of parallel squares in your three-dimensional world. As such, they are parallel and will have their single vanishing point. This vanishing point must be constructed first, in order to construct squares.

Again, find yourself an introduction to perspective, it shows up every now and then in this Forum, if you really, really, really want me to use the Search features for you, just ask, and I will refuse...

11. Registered User Level 1 Gladiator: Andabatae
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I'm sorry but I don't understand, why three vps and so on? Let me ask this using other words: can you tell me how do you verify you have a perfect square in prospective?
I found few topics about this but no one really exaplain how to find sides of a square, some of them are really old and example images are not available anymore.

12. Diamond Bullet Level 17 Gladiator: Spartacus' Dimachaeri
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Daafone, artistic perspective is not science. Its just a cheesy quick fix to get some stuff in certain locations on your picture to look correct. As soon as you begin to rely on it, it will make your picture awkward looking. You must keep correcting it by eye.
Last edited by kev ferrara; April 26th, 2012 at 12:34 PM. Reason: why muddy the waters...

13. Not to mention...BUY A BOOK.

14. Registered User Level 1 Gladiator: Andabatae
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Please point me to a book, in my university books I cannot find anything about perfect squares

15. Sorry....I'm not a hand-holder type. There are hundreds of books on perspective. Pick one. I have seven.

16. Registered User Level 2 Gladiator: Ordinarii
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http://www.handprint.com/HP/WCL/pers...#measurepoints
Also, about Anid's diagram... all parallel lines on the same plane will converge on the same horizon line. The diagonals of the squares and their sides are on the same plane, meaning that this "3rd vanishing point" must be on same horizon as the other two...

17. Deleted my posts on account I don't want incorrect information sticking around.

I 'squared' away, so to speak, my earlier mistake but I'm not going to bother any farther, as evidently squares in perspective are some arcane secret to only be answered with "read the fucking manual" and "Look up your own tutorial, don't bother me".

Not that it's everyone's attitude, but it seems to be the prevailing one.

So sorry Daafone, I guess go read a book or figure it out or something.

18. Registered User Level 1 Gladiator: Andabatae
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@Anid Maro: thanks for your help

19. I don't think it should be "Go read a damn book"

I think the problem is possibly a person should read it first, and what can't be explained should be asked. I've seen threads ask about perspective after the person has read a book and gained better understanding.

A good amount of the information is from people repeating what they've learned from a book combined with personal experience.

Also Perspective Made Easy is a very CHEAP book

20. Jester Level 7 Gladiator: Samnite
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Originally Posted by Arshes Nei
I don't think it should be "Go read a damn book"
I never said that, I wrote 'RTFM'...

21. Registered User Level 1 Gladiator: Andabatae
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Arshes, I'm trying to figure this out since months, do you really think I didn't read anything about perspective? My difficoult is due to terms as english isn't my main language.

22. Originally Posted by daafone
Arshes, I'm trying to figure this out since months, do you really think I didn't read anything about perspective? My difficoult is due to terms as english isn't my main language.
English being a second language is understandable, but reading may not be comprehending.

When you want a "perfect square" do you understand it's relevant in terms of perspective?

And really, I've been figuring out perspective for years, and I know people still trying to figure it out even as professionals.

23. Jester Level 7 Gladiator: Samnite
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Originally Posted by kev ferrara
Daafone, artistic perspective is not science. Its just a cheesy quick fix to get some stuff in certain locations on your picture to look correct. As soon as you begin to rely on it, it will make your picture awkward looking. You must keep correcting it by eye.
I agree here. However, if things are taught, then I prefer a correct approach. Personally, I like to include a perfect square in my perspective construction, it helps me to measure things up. I know about measuring points, up to 3-point perspective, and admit I never use them...

In my first year in art school, I almost wetted myself when a teacher showed us how to construct a square in perspective, using a bisection of an angle, which does not work, and gives verifiably bad results. On my request for proof or reference, he told me that this is so simple that a proof is not needed, the old Greeks already did it this way. Last time I checked, the school still teaches it this way. I don't mind if things are kept simple, I do revolt when people teach crap.

24. Registered User Level 1 Gladiator: Andabatae
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eezacque: I agree with you, I can also show several books (and internet tutorials) where a "perfect" square is explained using several and crap methods. And yes, squares are good in order to misure a figure (aspect ratio)
When you draw a square you can draw it in several ways but how do you know if it is a perfect square in that perspective?
Oh, perspective is *science*, think about how computers softwares implement that, I read these books too and I didn't find any solution to this question.

25. Originally Posted by Anid Maro
I 'squared' away, so to speak, my earlier mistake but I'm not going to bother any farther, as evidently squares in perspective are some arcane secret to only be answered with "read the fucking manual" and "Look up your own tutorial, don't bother me".

Not that it's everyone's attitude, but it seems to be the prevailing one.

So sorry Daafone, I guess go read a book or figure it out or something.
The prevailing attitude of "RTFM" is mostly because the explanation is 1) lengthy and 2) requires illustrations, and it's understandable that most people won't bother to spend 2 hours writing and illustrating something that can be found out from books.

And I think that going to read a book is a good idea for you. Your deleted advice wasn't quite right.

That said... it is a bit of "arcane" knowledge, for some reason. Most books on perspective either omit it, don't mention that the method can be used to build a square of specific size, or make it very challenging to understand.

I built this demo rather quickly from memory, so double-checks are welcome. I think I did it correctly, but it's rather late in the night, and if I botched it, I'm sorry. It's a modified "architect's method" - real architects start with an elevation plan, and we start from the perspective, so we have to build the elevation plan in correct relationship to the perspective first. Once you pinpoint the elevation plan size and position, then it's the regular trick of diagonals used to locate an unknown point from two known ones.

You can extend this method to all sorts of precise measurements in perspective.

26. Originally Posted by kev ferrara
Daafone, artistic perspective is not science. Its just a cheesy quick fix to get some stuff in certain locations on your picture to look correct. As soon as you begin to rely on it, it will make your picture awkward looking. You must keep correcting it by eye.
It's very much a science, Kev. If you "fake it" and eyeball everything, it does not mean that there is no method to do it precisely.

27. Registered User Level 1 Gladiator: Andabatae
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arenhaus: I love your method, I was trying to do the same. I'll try it ASAP!

28. Originally Posted by Anid Maro
Deleted my posts on account I don't want incorrect information sticking around.

I 'squared' away, so to speak, my earlier mistake but I'm not going to bother any farther, as evidently squares in perspective are some arcane secret to only be answered with "read the fucking manual" and "Look up your own tutorial, don't bother me".

Not that it's everyone's attitude, but it seems to be the prevailing one.

So sorry Daafone, I guess go read a book or figure it out or something.
Gimme a fucking break Anid. If you need someone to show you how to read a book you're lost from the start.

And I'm sorry, "read a book or figure it out or something" is exactly right.

Perspective is well understood and has been for 600 years. There's mountains of material written on it. Some makes sense to some people, some makes sense to others...the individual needs to care enough, and be curious enough about it to not have someone walk them through their obtuse little micro-question.

Edit: BTW, never, in my wildest dreams would I have whined about this kind of thing and kept pestering people about it. I would have read the fucking manual and gone and figured it out. I'm guessing any other professional artist on here did the same.

29. Registered User Level 1 Gladiator: Andabatae
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Can we please talk only about my question? This thread may be useful in future to others, so why do we have to flame?