How do I measure lines in perspective?

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    How do I measure lines in perspective?

    Let's imagine that I want to draw a cube in perspective (1, 2, 3 point - doesn't matter) - how do I measure the lines to make sure each of them is equally long? Is there some sort of technique that you use to measure the length?

    I've tried doing it by feeling but the results are unsatisfactory.

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  3. #2
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    Can we see these results?
    Maybe we can see what exactly you are having problems with.

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    http://postimg.org/image/vyd3vacij/

    How do I make sure x, y and z are all the exact same length?

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    Study 'measuring points' from one of the standard manuals on perspective.

    Grinnikend door het leven...
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    Could you be more specific? Any sources you'd like to suggest?

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    Norling: Perspective Made Easy - p. 200 onward
    Loomis: Successful Drawing - p. 40 onward

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  9. #7
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    Thanks! I've just gone briefly over the Loomis book and I'm guessing you're talking about the "architect method"? The equal spacing seems only relevant for a single direction...

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    Yes, look up "architect's method" of building perspective. If you want a book, Norling's "Perspective Made Easy" has a tutorial; Loomis's is not as good on this matter.

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    Okay, so I've tried the architect method and I just can't seem to get it right. Could somebody please draw a cube with it and post it so that I can see what I'm doing wrong?
    Also, is the GL = (HL - PP) / 2?

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    Note that this does not apply to 3-pt perspective...

    Grinnikend door het leven...
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    Here are step-by-step instructions on how to set up a measuring system in 3pt perspective, let alone how to draw a cube in 3pp:

    http://handprint.com/HP/WCL/perspect4.html

    But, if you don’t have a strong enough grasp of perspective, 1 and 2 pt, that will only confuse the hell out of you.
    I suggest clicking on the spiral drops icon to start at the beginning and read through the material carefully, multiple times if necessary, and draft every diagram until it all sinks in.
    Everything you’ll need to know about linear perspective drawing is right there:

    http://handprint.com/HP/WCL/tech10.html#index

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    Thanks for all the info!

    I've realized that the reason my cube wasn't turning out right was because I wasn't using any perspective at all (I'm such a dumbass...) but just fudging it. The architect method, even after LaCan's generous efforts STILL turns out wild results so I decided to just go with good old 2PP and fudge the corners. Surprisingly, it works adequately and more importantly, takes less time than the AM. Not only that, but I also discovered a nice way to quickly fudge the dimensions, if anyone is interested I'll be happy to post it.

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    Quote Originally Posted by l33t fl33t View Post
    Not only that, but I also discovered a nice way to quickly fudge the dimensions, if anyone is interested I'll be happy to post it.
    I'm always willing to learn, so I am interested! One word of caveat: fudging a cube might be doable, but if you're fudging multiple objects in space, this space might start falling apart real easily. So, each chair and table might look correctly fudged, but they can never coexist in the same room. The Architect's Method is an investment, it may take some practice to get it, and people here are generally helpful enough to help you out, but in the end, it really pays! This is even more the case for setting up measure points for 2-pt and 3-pt perspective...

    Grinnikend door het leven...
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    Now that I've actually gotten around to making it, the technique seems kind of silly but still, if it helps somebody...

    http://postimg.org/image/901irj2pz/

    http://postimg.org/image/5hpiv51tz/

    So, you just take your regular old 2PP and draw a vertical line and after that, rather than going draw/erase/repeat until you get the other lines right, you just draw two lines towards a PP on a separate layer and use the select tool to delete the parts you don't need. If you make a mistake (erase too little or too much), just undo and move the selection until you get it right.

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    Quote Originally Posted by l33t fl33t View Post
    Now that I've actually gotten around to making it, the technique seems kind of silly but still, if it helps somebody...

    http://postimg.org/image/901irj2pz/

    http://postimg.org/image/5hpiv51tz/

    So, you just take your regular old 2PP and draw a vertical line and after that, rather than going draw/erase/repeat until you get the other lines right, you just draw two lines towards a PP on a separate layer and use the select tool to delete the parts you don't need. If you make a mistake (erase too little or too much), just undo and move the selection until you get it right.
    That is one way to do perspective on a digital platform: it leaves you clueless about how to get it right.
    Please study perspective...

    Grinnikend door het leven...
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  23. #17
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    Uh-oh, that doesn't sound good. Care to explain?

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    Quote Originally Posted by l33t fl33t View Post
    Uh-oh, that doesn't sound good. Care to explain?
    The right side of your cube, which is supposed to be a square in perspective, has a larger height than its foreshortened width, so it cannot possibly be correct. All the fudging of the world is not going to save your behind if you don't understand the basics. Forget digital, get a ruler (a straight thing, usually wood or metal, often with little marks and symbols along one edge) and a pencil (a piece of rainforest with a black core, you need to carefully remove part of the rainforest to scratch the core across a surface, to leave a dark trail), find one of the recommended manuals on perspective and eat yourself through...

    Grinnikend door het leven...
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    Ya' know, there's no need to be snide. I don't think the questions I asked were asked in a rude way and my attempt at sharing some of what I learned, though botched, was made with the best intentions. But I guess a little civility and polite behaviour is too much to ask on the Internet, no?

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    Quote Originally Posted by l33t fl33t View Post
    Ya' know, there's no need to be snide. I don't think the questions I asked were asked in a rude way and my attempt at sharing some of what I learned, though botched, was made with the best intentions. But I guess a little civility and polite behaviour is too much to ask on the Internet, no?
    People here pointed you to the correct sources on perspective, as this is about construction and not about feeling or fudging.
    Instead of trying to understand the sources, possibly by asking questions, you go into a second round of feeling and fudging, and when I tell you once more to study perspective, you're complaining I'm not polite?

    Grinnikend door het leven...
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  28. #21
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    You misunderstand - it's not your message that I have a problem with - it's the way you're delivering it. For example...

    get a ruler (a straight thing, usually wood or metal, often with little marks and symbols along one edge) and a pencil (a piece of rainforest with a black core, you need to carefully remove part of the rainforest to scratch the core across a surface, to leave a dark trail)
    Is this tone truly necessary?

    Furthermore, I'm thankful for all the help I've received from the awesome members of this community - what I do with that information, however, is my own business. If you have a problem with that, may I suggest you stop giving advice? That way you'll be absolutely sure not to waste your time on, ahem, people like me who will do what they want with said information.

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  29. #22
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    Quote Originally Posted by l33t fl33t View Post
    Furthermore, I'm thankful for all the help I've received from the awesome members of this community - what I do with that information, however, is my own business. If you have a problem with that, may I suggest you stop giving advice? That way you'll be absolutely sure not to waste your time on, ahem, people like me who will do what they want with said information.
    Whether eezacque's sarcasm had been called for or not, he raised a valid point: you had gotten advice here, then went on to invent your own not-exactly-working things instead of trying to implement that advice. And then came back for more advice, where people instantly saw you had not been following the previous one.

    Do you really think this would make people more interested in helping you?

    What you do with advice is your business indeed, but don't expect people to enjoy the way you ignore it. After all, they volunteered their time and knowledge on your request.

    I second the recommendation: don't try to fudge it, don't try to do it digitally, learn to plot perspective with a ruler and a sharp pencil the way smart people had figured out painstakingly in generations before you. Inventing the bicycle from scratch might feel like fun, but you might find you can invent bicycles faster if you learn to build a traditional one first.

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  31. #23
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    It has been utterly uncalled for - even more so when you consider all the people that posted on ConceptArt through the years and behaved far, far worse that I have. Furthermore, if advice is going to come packaged with sarcasm and insults as eezacque's has, then I insist that the author keeps it to himself. I'm sure I'll manage without it.

    Also, for anyone else who is reading - consider yourself warned - I may or may not heed your advice. I may or may not do what you tell me to do. If this is a major issue for you, if you insist on me following your advice to the letter, then please - don't offer me any advice, because I can't guarantee that I'll listen to it. I am of course grateful for it, but if you expect me to listen to your advice as a condition for receiving it - please, don't bother. Before giving me your advice, assume that I'll ignore it, won't read it or won't listen to it. If after all this, you still feel like sharing your advice, please do so. I'm grateful for it.

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  32. #24
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    How many people telling you to do it the correct way does it take before you will listen? I presume you're here to learn and improve your art? If so better start listening and taking heed.

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    ...You know... When you so rudely suggest that people should respond to you in a certain way or shut up, then please consider it goes both ways.

    The best advice for you right now gotta be:
    Shut up or say thank you! If you have any complaints about how a message got delivered, then keep it to yourself.
    If you are so smart to know that "a lot of people behave worse than you", then you should also know that whenever you are starting out with something like this, they ALWAYS want you to go traditional first.

    The attitude here sometimes sucks. Sarcasm, ridicule, shit like that... And then of course exaggerated response from people who totally can't handle it.

    Since you so nicely encourage me to assume you won't read this...

    I actually just wanted to say:
    Thanks people for the advice on perspective, I was looking for something like that too


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  34. #26
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    Quote Originally Posted by Trixtar View Post
    ...You know... When you so rudely suggest that people should respond to you in a certain way or shut up, then please consider it goes both ways.
    So asking for a response in a civilized, polite manner is now considered "rude"? Should I be happy people aren't screaming at me in all caps lock and bad spelling?

    Shut up or say thank you! If you have any complaints about how a message got delivered, then keep it to yourself.
    I have said thank you. Multiple times. But people seem to gloss over that. And no, I won't "keep it to myself" when I'm being insulted. Why? Two reasons - first, because I don't have to and second, if I behaved that way towards eezacque I would - quite rightly - be called out for it. So you see, it's really quite simple - if I'm polite with you, you'll be polite with me. If I treat you like a human being with consideration for your feelings - I damn well expect you to treat me the same way.

    Quote Originally Posted by Black Spot View Post
    How many people telling you to do it the correct way does it take before you will listen?
    I think we've already moved away from perspective and drawing in general and are currently arguing about how to treat each other and the merits of politely stating one's opinions.

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  35. #27
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    No, you moved the goal posts. Go back and reread the advice you were given, digest it and figure it out how it works in your mind before dismissing it as unusable by your low standards. If you settle for fudging, you will always settle for less.

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  37. #28
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    The real question is why you can't replicate architect's method after you've been given reference to several comprehensive resources, including drool-proof recipes and a direct example. Let's see those failed attempts to diagnose what's wrong.

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  38. #29
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    *shrugs* What have I got to lose?

    http://postimg.org/image/5vz4jhpz5/

    Don't bother too much with the second image, I know they VPS are too close that's why the second cube looks distorted. The first picture is what concerns me. Whenever I skew the plan to one side one plane of the cube ends up looking too short.

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  39. #30
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    Your VPs don’t comply with the skew angles the cube makes with the Picture Plane (x° and y° in my diagram). Also, watch the vertical distance between the Picture Plane/plan view and the horizon. It is not an arbitrary distance. If it’s not right it will introduce errors in the drawing. Note points A and B in figure 1. This is wrong. A and B should be one point, as in figure 2. It’s best to produce one large and accurate cube and use it as a world 3d grid to confine objects to. 2pp gets wonky quickly if you don't restrict the circle/cone of view.

    FYI—I hardly ever use 2 pt perspective. 3pt (as well as 5 pt curvilinear for wide angle views) produces the best results (regardless of how parallel the verticals appear in 3pp). Most of what we focus on has planes and straight edges that are skewed from being perpendicular to our line of sight.

    2pp2.jpg

    Last edited by bill618; April 28th, 2013 at 12:00 PM.
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