Draw a perfect square using two vanishing points
Join the #1 Art Workshop - LevelUpJoin Premium Art Workshop

Page 1 of 3 1 2 3 LastLast
Results 1 to 30 of 65
  1. #1
    Join Date
    Apr 2012
    Posts
    17
    Thanks
    3
    Thanked 0 Times in 0 Posts
    Follows
    0
    Following
    0

    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!

    Reply With Quote Reply With Quote  

  2. #2
    Join Date
    Apr 2012
    Posts
    17
    Thanks
    3
    Thanked 0 Times in 0 Posts
    Follows
    0
    Following
    0
    I'm sorry but this doesn't seem to work. Example:

    Attached Images Attached Images  
    Reply With Quote Reply With Quote  

  3. #3
    Join Date
    Apr 2012
    Posts
    17
    Thanks
    3
    Thanked 0 Times in 0 Posts
    Follows
    0
    Following
    0
    Those vps are intersections between rectangle sides computed by a software.

    Reply With Quote Reply With Quote  

  4. #4
    Join Date
    Jun 2007
    Location
    Toronto, Ontario
    Posts
    1,148
    Thanks
    9
    Thanked 400 Times in 274 Posts
    Follows
    0
    Following
    0
    Quote Originally Posted by Anid Maro View Post
    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

    Reply With Quote Reply With Quote  

  5. #5
    Elwell's Avatar
    Elwell is offline Sticks Like Grim Death Level 17 Gladiator: Spartacus' Dimachaeri
    Join Date
    May 2003
    Location
    Hudson River valley, NY
    Posts
    16,212
    Thanks
    4,879
    Thanked 16,666 Times in 5,020 Posts
    Follows
    0
    Following
    0
    Anid, those verticals will have to converge as well.


    Tristan Elwell
    **Finished Work Thread **Process Thread **Edges Tutorial

    Crash Course for Artists, Illustrators, and Cartoonists, NYC, the 2013 Edition!

    "Work is more fun than fun."
    -John Cale

    "Art is supposed to punch you in the brain, and it's supposed to stay punched."
    -Marc Maron
    Reply With Quote Reply With Quote  

  6. The Following User Says Thank You to Elwell For This Useful Post:


  7. #6
    Join Date
    Apr 2012
    Posts
    17
    Thanks
    3
    Thanked 0 Times in 0 Posts
    Follows
    0
    Following
    0
    Mhhh... I would like to draw the square inside the rectangle... Can't I bisect a corner or something similar?

    Reply With Quote Reply With Quote  

  8. #7
    Elwell's Avatar
    Elwell is offline Sticks Like Grim Death Level 17 Gladiator: Spartacus' Dimachaeri
    Join Date
    May 2003
    Location
    Hudson River valley, NY
    Posts
    16,212
    Thanks
    4,879
    Thanked 16,666 Times in 5,020 Posts
    Follows
    0
    Following
    0
    Other way.


    Tristan Elwell
    **Finished Work Thread **Process Thread **Edges Tutorial

    Crash Course for Artists, Illustrators, and Cartoonists, NYC, the 2013 Edition!

    "Work is more fun than fun."
    -John Cale

    "Art is supposed to punch you in the brain, and it's supposed to stay punched."
    -Marc Maron
    Reply With Quote Reply With Quote  

  9. The Following User Says Thank You to Elwell For This Useful Post:


  10. #8
    Join Date
    Apr 2012
    Posts
    17
    Thanks
    3
    Thanked 0 Times in 0 Posts
    Follows
    0
    Following
    0
    Ok, who can explain other ways to do this?

    Reply With Quote Reply With Quote  

  11. #9
    Join Date
    Aug 2008
    Location
    san francisco
    Posts
    46
    Thanks
    5
    Thanked 12 Times in 12 Posts
    Follows
    0
    Following
    0
    how do you determine if the third vp is up or down?

    Reply With Quote Reply With Quote  

  12. #10
    Join Date
    Jun 2007
    Location
    Toronto, Ontario
    Posts
    1,148
    Thanks
    9
    Thanked 400 Times in 274 Posts
    Follows
    0
    Following
    0
    Quote Originally Posted by Anid Maro View Post
    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...

    Reply With Quote Reply With Quote  

  13. #11
    Join Date
    Apr 2012
    Posts
    17
    Thanks
    3
    Thanked 0 Times in 0 Posts
    Follows
    0
    Following
    0
    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.

    Reply With Quote Reply With Quote  

  14. #12
    kev ferrara is offline Registered User Level 17 Gladiator: Spartacus' Dimachaeri
    Join Date
    Feb 2006
    Location
    Fallingwater
    Posts
    5,059
    Thanks
    1,516
    Thanked 5,150 Times in 1,700 Posts
    Follows
    0
    Following
    0
    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...
    At least Icarus tried!


    My Process: Dead Rider Graphic Novel (Dark Horse Comics) plus oil paintings, pencils and other goodies:
    http://www.conceptart.org/forums/sho...d.php?t=101106

    My "Smilechild" Music. Plus a medley of Commercial Music Cues and a Folksy Jingle!:
    http://www.myspace.com/kevferrara
    Reply With Quote Reply With Quote  

  15. The Following 5 Users Say Thank You to kev ferrara For This Useful Post:


  16. #13
    JeffX99's Avatar
    JeffX99 is offline Registered User Level 17 Gladiator: Spartacus' Dimachaeri
    Join Date
    Apr 2009
    Location
    Northern California
    Posts
    5,234
    Thanks
    3,512
    Thanked 4,896 Times in 2,544 Posts
    Follows
    0
    Following
    0
    Not to mention...BUY A BOOK.

    What would Caravaggio do?
    _________________________

    Portfolio
    Plein Air
    Digital
    Still Life
    Sight Measuring
    Fundamentals
    Reply With Quote Reply With Quote  

  17. The Following 2 Users Say Thank You to JeffX99 For This Useful Post:


  18. #14
    Join Date
    Apr 2012
    Posts
    17
    Thanks
    3
    Thanked 0 Times in 0 Posts
    Follows
    0
    Following
    0
    Please point me to a book, in my university books I cannot find anything about perfect squares

    Reply With Quote Reply With Quote  

  19. #15
    JeffX99's Avatar
    JeffX99 is offline Registered User Level 17 Gladiator: Spartacus' Dimachaeri
    Join Date
    Apr 2009
    Location
    Northern California
    Posts
    5,234
    Thanks
    3,512
    Thanked 4,896 Times in 2,544 Posts
    Follows
    0
    Following
    0
    Sorry....I'm not a hand-holder type. There are hundreds of books on perspective. Pick one. I have seven.

    What would Caravaggio do?
    _________________________

    Portfolio
    Plein Air
    Digital
    Still Life
    Sight Measuring
    Fundamentals
    Reply With Quote Reply With Quote  

  20. The Following 2 Users Say Thank You to JeffX99 For This Useful Post:


  21. #16
    Join Date
    Nov 2009
    Posts
    58
    Thanks
    4
    Thanked 19 Times in 12 Posts
    Follows
    0
    Following
    0
    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...

    Reply With Quote Reply With Quote  

  22. #17
    Join Date
    Nov 2007
    Posts
    2,002
    Thanks
    891
    Thanked 1,010 Times in 539 Posts
    Follows
    0
    Following
    0
    Reply With Quote Reply With Quote  

  23. #18
    Anid Maro's Avatar
    Anid Maro is offline Psychotic Eldritch Zeppelin Level 9 Gladiator: Hoplomachi
    Join Date
    Dec 2006
    Posts
    1,378
    Thanks
    669
    Thanked 537 Times in 295 Posts
    Follows
    0
    Following
    0
    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.

    -My work can be found at my local directory thread.
    Reply With Quote Reply With Quote  

  24. The Following 2 Users Say Thank You to Anid Maro For This Useful Post:


  25. #19
    Join Date
    Apr 2012
    Posts
    17
    Thanks
    3
    Thanked 0 Times in 0 Posts
    Follows
    0
    Following
    0
    @Anid Maro: thanks for your help

    Reply With Quote Reply With Quote  

  26. #20
    Arshes Nei's Avatar
    Arshes Nei is offline Registered User Level 17 Gladiator: Spartacus' Dimachaeri
    Join Date
    Jun 2006
    Location
    Torrance, CA
    Posts
    6,802
    Thanks
    2,278
    Thanked 4,259 Times in 2,074 Posts
    Follows
    0
    Following
    0
    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

    Reply With Quote Reply With Quote  

  27. #21
    Join Date
    Jun 2007
    Location
    Toronto, Ontario
    Posts
    1,148
    Thanks
    9
    Thanked 400 Times in 274 Posts
    Follows
    0
    Following
    0
    Quote Originally Posted by Arshes Nei View Post
    I don't think it should be "Go read a damn book"
    I never said that, I wrote 'RTFM'...

    Reply With Quote Reply With Quote  

  28. #22
    Join Date
    Apr 2012
    Posts
    17
    Thanks
    3
    Thanked 0 Times in 0 Posts
    Follows
    0
    Following
    0
    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.

    Reply With Quote Reply With Quote  

  29. #23
    Arshes Nei's Avatar
    Arshes Nei is offline Registered User Level 17 Gladiator: Spartacus' Dimachaeri
    Join Date
    Jun 2006
    Location
    Torrance, CA
    Posts
    6,802
    Thanks
    2,278
    Thanked 4,259 Times in 2,074 Posts
    Follows
    0
    Following
    0
    Quote Originally Posted by daafone View Post
    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.

    Reply With Quote Reply With Quote  

  30. #24
    Join Date
    Jun 2007
    Location
    Toronto, Ontario
    Posts
    1,148
    Thanks
    9
    Thanked 400 Times in 274 Posts
    Follows
    0
    Following
    0
    Quote Originally Posted by kev ferrara View Post
    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.

    Reply With Quote Reply With Quote  

  31. #25
    Join Date
    Apr 2012
    Posts
    17
    Thanks
    3
    Thanked 0 Times in 0 Posts
    Follows
    0
    Following
    0
    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.

    Reply With Quote Reply With Quote  

  32. #26
    Join Date
    Jan 2010
    Location
    Haifa, Israel
    Posts
    3,859
    Thanks
    2,298
    Thanked 2,234 Times in 1,354 Posts
    Follows
    0
    Following
    0
    Quote Originally Posted by Anid Maro View Post
    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.

    Attached Images Attached Images  
    Reply With Quote Reply With Quote  

  33. The Following 9 Users Say Thank You to arenhaus For This Useful Post:


  34. #27
    Join Date
    Jan 2010
    Location
    Haifa, Israel
    Posts
    3,859
    Thanks
    2,298
    Thanked 2,234 Times in 1,354 Posts
    Follows
    0
    Following
    0
    Quote Originally Posted by kev ferrara View Post
    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.

    Reply With Quote Reply With Quote  

  35. #28
    Join Date
    Apr 2012
    Posts
    17
    Thanks
    3
    Thanked 0 Times in 0 Posts
    Follows
    0
    Following
    0
    arenhaus: I love your method, I was trying to do the same. I'll try it ASAP!

    Reply With Quote Reply With Quote  

  36. #29
    JeffX99's Avatar
    JeffX99 is offline Registered User Level 17 Gladiator: Spartacus' Dimachaeri
    Join Date
    Apr 2009
    Location
    Northern California
    Posts
    5,234
    Thanks
    3,512
    Thanked 4,896 Times in 2,544 Posts
    Follows
    0
    Following
    0
    Quote Originally Posted by Anid Maro View Post
    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.

    What would Caravaggio do?
    _________________________

    Portfolio
    Plein Air
    Digital
    Still Life
    Sight Measuring
    Fundamentals
    Reply With Quote Reply With Quote  

  37. #30
    Join Date
    Apr 2012
    Posts
    17
    Thanks
    3
    Thanked 0 Times in 0 Posts
    Follows
    0
    Following
    0
    Can we please talk only about my question? This thread may be useful in future to others, so why do we have to flame?

    Reply With Quote Reply With Quote  

Page 1 of 3 1 2 3 LastLast

Members who have read this thread: 5

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •