How to draw an exact cube by using perspective

[Jussi Tarvainen]

I've been learning perspective via a book called "Creative perspective for artists and illustrators" by Ernest Watson. At times the book gets a bit confuing so I thought I'd ask a question here.

If you want to draw a perfect cube by using two point perspective how do you measure the height compared to the lengths of the sides? Or is that impossible and you just have to know what a cube looks in life and do the judgement by eye. My question is if there is a logical way to measure it or just figure by eye?

Thanks in advance!

[rattsang]

there are two ways that i know to do it, one of course is by eye and the other is thru the use of angles and measurements which in my opinion isn't worth the bother your talking alot of extra work for nothing. a perfect and near perfect cube is indistinguishable in perspective.

it is far easier to train your eye to tell if it looks right subconsciously you know what it looks like thats how you know when your looking at a cube in real life.

you need to look hard at the positions of the lines your drawing an be critical of errors. it will take time and practice but its worth it. also its go to note your bias- everyone has a bias -they will either draw a square to long or to wide, consistently. you need to know your bias and look out for it, my bias is drawing it to long.

also the order you draw the lines in is critical. try to complete full planes b4 moving on to the next plane.

the number indicate the order in which i drew the lines( this is the full drawing fully freehand , no guides no measurements no horizon line)

obviously if you use some construction your cube will be better , but i think a horizon line and some receding parallels is the most you need.

if you want to know the long complicated method for measuring it it is explained in "the complete guide to perspective" by john raynes.

[Jussi Tarvainen]

rattsang: Thank you very much for your insight and tips for drawing the cube. I was wondering if there was a fairly easy way to do it by measuring but your answer made it sound clear that it is quite too complicated and that I ought to keep drawing those cube's from reference. Also that's a great tip to keep an eye on the sides which I tend to draw too long or high and the tip about the order of construction.

Cheers!

[nate01776]

Hey Yuza,
Im brand new to the forum, but was browsing the tutorial section and thought i might be able to help you out a bit. We studied perspective briefly in Uni last year and thought id mock up a quick tutorial on two point perspective(this is way eaiser to do with pen and paper, unfortunatly, I dont have a scanner where i am atm, so photoshop it has to be)...


~First step is to draw your horizon line and mark the end points, simple enough..


~This step is pretty crucial, you want to pick where your closet corner is going to be, and then just mark it straight down however big you want your box.


~Then connect the top and bottom points of the line to the edges of your horizon line!


~Heres a somewhat tricky bit, you need to eye in where you want the furthest edges of your cube to sit. Generally, this looks good wherever you sit them, but for a perfect cube, youll want to take some time to measure them out along the top and bottom to make sure its even...


~Now that youve got that sorted, darken in your final lines and bust out the eraser.


~and there you have it, a cube!!


~and its always fun to throw in a little shading to mix things up!


so thats how I learnt to draw cubes in a forced perspective. The previous tutorial doesnt actually use a true perpective, this way is much more flexible. You can stop the vertical line above the horizon, draw the whole thing below, draw it right on it or draw more than one and use the same horizon points to put them all into the same perspective plane. hope this helped you and if you have any questions just ask! this is my first tutorial, so sorry if its a bit rambling!!

[Seedling]

Thanks for sharing the tutorial, Nate. I have to point out, however, that while you have drawn a nice box, it is not is not technically a *perfect* cube. More construction methods are required for a mathematically perfect cube.

Dang it, I may have to pick up on Perspective 101 again. . . the link is in my sig if anyone is looking for perspective basics. However, I have not included anything on perfect cubes yet. Sorry!

[Jussi Tarvainen]

Nate01776: Thanks for the tutorial, much appreciated. Though I agree with Seedling. I was curious if there was a mathematical way of calculating each of the sides. But the fact is it is better to learn it from the nature like Rattsang said.

Though I am interested of the mathematical way of doing this as well just out of the curiosity and it would be nice to have some way to check if a cube drawing from your mind is close to the correct one.

So Seedling, the challenge is on to see an update for a perfect cube tutorial in your Perspective 101 thread Would be awesome.

Cheers

[Seedling]

Heehe. . . first I have to learn how to do it.

[Craig D]

YuZa
as Watson says, the best way is to draw hundreds until you "know" what they look like. Or do one in Google sketchup and trace it!

But if you really need a perfect one, you can use plan projection to do so.
I kind of know how to do it, but I think we need someone more qualified to do a demo.

Try sending a PM to Yoitsi about this thread??

edit add: see link for a starting point http://studiochalkboard.evansville.edu/lp-square.html

[artiphats]

coincidentally I came across this site via google when I was working on the last IDW in the weeklies:

http://www.sonjebasa.net/Instruction/2PtPerspective.pdf

this is the EXACT way to know where to put your points, no guessing. Check out my results here:

http://conceptart.org/forums/showthread.php?t=135386
(updates on pages 1 and 2)

and the final thread here

http://conceptart.org/forums/showthread.php?t=136286

for you members please feel free to vote for your favorite and leave crits for us, only 3 people entered this round, hopefully next round will be a better turnout.

thanks and hope the link to www.sonjebasa.net helps, there is a list of helpful links in the instruction page.

[nate01776]

sorry, thought you were lookin to do 2point perspective... not sure how to measure out a perfect cube, i usually just eye it as best i can...

[artiphats]

sorry, thought you were lookin to do 2point perspective... not sure how to measure out a perfect cube, i usually just eye it as best i can...

no you were right about the 2-point. but there IS a way to measure, check the links I posted above.

If I have time tonight I will post a step by step here myself, the one in the link is really good but there are a couple steps that could use just a bit more information, I think.

[artiphats]

ok boys and girls, here is my best shot at a tutorial for a cube, let me know if anything doesnt make sense and I'll try and edit it. kinda long I know but this was the best I could do and still try and make it all clear and easy.

I didnt double check it all, so if I see a mistake (or you see one) I will fix it asap. Good luck!

-Ray

[Azalin]

Wow, cool tutorial, i´ve allways asked myself how to do it, not that everytime i draw a cube im going to use this...
cheers

[nate01776]

ahhhh, i had no idea it was so easy! no, but i will definatly save this adn print it out to put in the reference folder, awesome stuff...

[Jussi Tarvainen]

Nice one Ray, thanks for making the clear cut tutorial of this. Damn, seriously big thanks!

[artiphats]

no problem guys, it's the least I could do for fellow artists. Look for another tutorial soon, concerning how to make cool silhouettes in PS with just text. Simple, but I think might be helpful when you are low on ideas, creativity, or inspiration.

-Ray

[M3tr0idgrl]

i dunno if this thread is dead or not but.... how about drawing 5 perfect cubes in two point perspective? can anyone do it?

[ikken]

what do you mean? drawing 5 perfect cubes in the same 2-point set-up, just spaced out a bit?
keep in mind objects can have their own vanishing points in real life (just watch closely how buildings are warping around while going on a bus/on a train)