[29A]

This is what I came up with after a few minutes in PS, still don't have a scanner so here we go... oh, and I just realized why the box looks all screwed up, my mistake with the construction lines...



damn, just missed the allmighty spooge...

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I'm not defect!

[This message has been edited by 29A (edited May 25, 2000).]

[This message has been edited by 29A (edited May 25, 2000).]

[Nex]

I knew something was wrong...

maybe like this?

[Plop]

Try 3
I tried to get the cubes right on this one, i don't think it worked. How do you get the right depth of the cube? I am still guessing it.



[This message has been edited by Plop (edited May 26, 2000).]

[29A]

Nex: check this out, it helped me alot to learn this, that horisontal line is the eye-line, there should be only one of those. That's why your box seems to be skewed...



I'll leave the shading/shadows/values to someone who know that better than me... spooge or fred for example.

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I'm not defect!

[sydneyshan]

Here's my attempt. Didn't use the tablet as much as I'd thought- more 'planes' than anything.

Sorry to hear you'll be gone a while Spooge! We'll miss ya!

Comments please =)




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***********
Shannon Murdoch
www.bounce.to/shan
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[HumanClay]

I'm sick of cubes..



Done traditionally with markers.

HumanClay

[This message has been edited by HumanClay (edited May 26, 2000).]

[tzekin]

Here is what I've done with my tablet.



---a.tzekin
tzekin.iloveimac.com

[This message has been edited by tzekin (edited May 26, 2000).]

[This message has been edited by tzekin (edited May 26, 2000).]

[Sumaleth]

Here's my version of 'task one'.



Self critiq;

I don't think the shadows work terribly well, at least not as nicely as they do in Spooge's cubes image.

I probably should have made the top of the cube a little brighter, it's not matching the bright top of the cyclinder at the moment.

The cube still doesn't look square, and thats after I already cropped it back a bit (thats where the brighter white on the top went .

I probably should have tried more layouts to get something more interesting. For starters I would have prefered the light up much higher so that the interesting parts of the shadow didn't stretch out so far from the objects.

I think a tighter crop would look a lot better but I spent so long working out the finer details of the shadows that I had to leave them in .

--

I have to say that I found this to be an -excellent- excersize and it really got me thinking about a lot of things. I probably benefited a lot from waiting before attempting the task since it meant I also had Spooge's comments to work from and Francis' -very- handy lighting diagram.

I think possibly tute 1 could have been broken down even further, with separate tasks given for perspective drawning, rendering, shadowing, etc. After I started working out the construction lines I got a feeling that I'd bitten off more than I could chew in one go .

All of the straight angles are done with (fairly extensive) construction lines but the curves were all done by eye. I have other work to do you know .

--

Spooge; I'd be very interested to hear your thoughts on how I could make it look more realistic.

Cheers,
Row.

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http://www.fountainheadent.com
http://impact.frag.com (currently offline..)

[Nex]

since I am doing nothing else lately but drawing boxes all the time ...
I have a question.. how do you construct cast shadow on another object. I tried it below (red pointer) but I think its not right.





[This message has been edited by Nex (edited May 26, 2000).]

[Francis]

He's right - that face is turned away from your light source, so there should be no cast shadow on that face.

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TeamGT Studios

[Nex]

its kind of logic but anyway i was not sure... thanks

[Dizzogg]

Here's mine......I kinda messed up the shadows on the right cube but anyways....

They need a bit of work Im sure, as why Im here

Let me have it.....

[AliasMoze]

Here's my first image (finished earlier than I'd thought). Also, I added some lines in the beginning to help me and included a pic that shows the light direction in red.

I used front light, which probably wasn't such a hot idea. I'll do some more lit from the side and back

Hit me with the bad news, Fred!




[This message has been edited by AliasMoze (edited May 26, 2000).]

[Hurri-cane]

it cant be as mucj light on that side the red arrow points....so there for there can be no 2dary shadow on it, and no shadow shall be cast


(if u understand my crappy explanation)

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-H-U-R-R-I-C-A-N-E-
[email protected] http://www.geocities.com/hurri_cane_1999/
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[This message has been edited by Hurri-cane (edited May 26, 2000).]

[spooge demon]

Let me just crack my knuckles here and we will begin.

This will be my last crit before I go to away for a while. i will try yo post, but I am not sure if I will be able.

Thanks to Francis for helping me out with the cast shadow info. Francis, could you do some shadow casting across objects? Stairs are a good example.

I am doing this til fred can take over again.

A few notes on where all this is headed. The assignments will gradually add one or two variables as each is mastered. The next drawing will be 2 matte cubes, one white, one black, on a white surface. Same idea, just black cube. It is tougher than you think. Then we do cylinders, then spheres. Once you are very comfortable with all this, then we start making something by combining these objects. When i had this class, we did a childs pull toy. Simple objects combined, with the start of a simple texture. later we introduce color, reflection, atmospheric perspective, etc. Each one of these variable must be isolated and studied, you can�t do it all at once. That is why I get after you when you go ahead. I have not seen the two white cubes exercise done without error yet, so why are you moving ahead. I challenge you- it is so simple no? Take the coin from my hand... just kidding. If you can�t get this correct, once we begin adding variables, you will be lost. Gotta get these basics right.

I reccommend getting a roman head, you know one of those all white things? Look at how light reacts on the simple forms we are playing with here, then look at the head. Do you see the nose is like a box, just squashed with a cylinder on top? The basic head is a sphere. Look at how the halftones on the top of the head (assuming top lighting) are brighter than the same on the chin. The head rolls away from the light, so even if the chin is still lit, it is a little darker. Do you see the cast shadow from the nose across the cheek? It is darker, just like the cast shadow from the cubes.

Onto the bloodletting

29a

Way too much contrast in lit side. Highly reflective material. Ambiguous surface local value. Core shadow should be farhter to the right, and reversed in curve. No reflected light in shaded side of cube. Cast shadow of sphere out of perspective. Box is not a cube. If you were attempting lens distortion, don�t- it just confusing. Sphere would also be distorted. No perspective on gradation of floor surface. If the lens is this wide, the far shadow edge should be foreshortened. Soft shadow on cube, hard shadow on sphere.

See? Just do 2 cubes- much easier.

Nex- Verticals are not vertical, shadows black, no modeling of reflected light in shaded side of cubes, no halftone gradation in lit top of cubes. Cubes not sitting on same plane, as 29a points out correctly. Left face of right cube is in shadow, but is much too light for that. Appears to be halftone (halftone is what is in light that is not highlight) Try to keep shadow ends on paper, it is good info that will help viewer quickly tell what is going on.

Tanis I will just talk about top cube. Right VP is too close to center of vision. Shadow is missingedge cast from top edge of cube. Not enought separation of value from top lit surface to vertical shaded surface. No modeling of halftones in lit vertical face. Linework AUUUGHH! Use values, not line. Draw your construction first(with line) and then place your drawing paper over that. Trace it. Do it by eye later, but now, just get it right so your eye learns.

MOO- Not cubes at all. Also, I never made it clear, both cubes are of the same size. Far cube is much bigger than front one. Unfortunate choice of lighting direction- light is tangent to a face, making it in neither light or shade. Much better and faster read arrange light so all faces fall in one or another. Reversed halftone gradation on left cube, should be lighter farther away, darker closer (further from light). Shadows not from same source. Good separation of light and dark, though, with exception noted above.

Binke Cube out of convergence, not a cube (left side too long) Shadow from sphere should be underneath sphere a little. Shadows appear to be from different light sources (they go in different directions) Good basic values on cube. Called good 1-2-3, or lit, halftone, shaded. Could exaggerate reflected light in shade of cube, esp with light bounce from close sphere. values on sphere too dark. Grey shape, not white. Core shadow wrapped too far around object for side light. Go darker right underneath sphere, where it sits on ground, because the sphere itself shades the surface that it sits on from diffuse ambient light (the light that prevents the shadows from going black) No cheating by running shadows off paper. Let�s see them. Oddly composed. Have a nice day, Binke sorry.

Darkmoon- similar comments on the lighting direction as MOO. Yours, however, is in shadow, so its better. Should be getting more reflected light on left shaded side of cube, cause the bright surface is very close and has little shadow. Could use more reflected light in right shaded side too. Loosing edge of top left edge. Slight tone behind to fix that. Shadow of top left edge is way out of perspective. This may help



Samdragon Same problem with tangent shadows. Muddled values from light to shade, very gray cubes, dude. Actually gray cubes with white tops. Bottom cube is not a cube, too deep. Shadow darker than shaded vertical sides. Too dark on surface, loosing light and shade feel. Right bottom edge of right cube converging too quickly. Keep at it, this is a good exercise for you.

Plop, your image is a white box with a little red x. Can�t say to much

Sydneyshan. EL too low to have 3rd VP. Right side of right cube way too dark. Shadows black. Is right faces of cubes in light or shadow? Surface appears grey. If right face of big cube is in shadow, no reflected light. Shadow edges loosing shape. Tighten up to give more info. Light direction as indicated by cast shadow shows light to be more from top than very dark top surfaces would indicate. Again, too dark in the halftones, making things look shiny. Keep at it, mate!

Humanclay,

Not matte surfaces, core shadow looks like reflection of something dark. Very little modeling of shaded side and halftones does not describe form, looks flat. Cast shadow on sphere and cone from two different sources. Ellipse of cylinder on top is too open. Same as bottom, perspective drawing, not isometric. Lit side very blown out, no form. Top of cylinder same value as side. Is the light more from top or side? make it one so you can show that turn of form. Good chance for relected light from cone into shaded side of sphere not used.

It is the training of ID to make all things look shiny. Fight it, learn why things look shiny, or it will follow you around like big scarlet letters �ID GUY� I know, I was there. It is not bad if this is where you will spend your professional life, but gawd, it is so limiting. learn contol over contrast to make things shiny or matte at will, you will be a much more capable illustrator. End sermon.

Tzekin- Shadow too black, shaded side of cube too black, top surface should be halftone, to light, but it has a darker right edge, giving a rounded read. Lit face is all one value. No convergence to right VP, looking like isometric drawing. You can use some tone behind the cube to show and edge. Try to not make the front face square to the picture plane (so that the top and bottom are parallel to the edge of the page). this flattens things out a bit. Read the above info on how to cast shadows correctly.

Sumaleth cast and object shadows too similar, loosing the edges. Too light on left shadow area of cone. Too dark overall, objects are grey. Core shadow too far to left on sphere . No halftone modeling in halftones on sphere, looks flat. Too much contrast on top of cylinder, looks rounded. Might want to reverse the figure-ground values on cube, surface darker, object lighter. Contrast ratio is good, as in pretty slight.

Nex, dizzogg aliasmoze, I will have to get to you later, out of time

I just looked at my cubes again. many errors, my eye has sharpened back up doing these crits. There is no end to the number of errors you can make with this simple excercise.

I hope you see how important I think this stuff is by the time I spend criting the work. you are not wasting time and effort by doing it.

If you think you are beyond it, do this exercise for me. With the same setup as these cubes (white surface, single point source, etc.) draw and render me a little red wagon. Yeah, those little things kids ride around in. Post it and I will crit it. I will even do the exercise myself if there is interest. but this is only if you think cubes are beneath you. i recommend sticking to the plan that we are following, one variable at a time. If you screw it up, will you go back and do the cubes? Please?

[Plop]

Bummer. I am hosting off of my desktop, had to reinstall windows. Images should work now.

[Frost]

Hey Spooge.

The critiques you give are great, and it definitely shows that you know what you're talking about. I'm just afraid no one here is able to see all those flaws that you do (no offense to Fred, Mozeman, or anyone), because I don't think anyone has as much experience as you do in this field -- so when you're gone, who's going to notice a 5% intensity error in a light reflection or such? Maybe I'm wrong.

Also, I just made this -- I think it could help. It's pretty much how simple light is calculated on surfaces in 3D renders (minus a few other influencing factors). I hope I did it right...



It's suppose to explain how light affects a surface depending on it's orientation with regards to light, and where this light bounces off to... most of you probably know that. In any case, it just made me realise how light is not a simple linear degradation from light to dark in its falloff... Spooge/Fred/Mozeman, anyone, care to explain?

I hope I didn't cause more damage than help with this.

cheers.

[Nex]

Frost: Thanks for explanation but I guess your shadow - line is wrong if that is supposed to be a sphere no? (this is more a question than a statement, I usually let the renderer do this job before this thread.)

[Frost]

Nex: Well, the shadow-line you mentioned is merely a slice of the sphere, and, it may not be clear in the drawing, but the view is non perspective, it is merely a straightfoward 2D representation so it illustrates clearly the point without having perspective in the way to confuse. (the shadow line is not wrong, but the light degradation within the lit side is).

The viewer (in the image above) is perfectly perpendicular to the axis-line between the light and sphere. Since the light is close to the sphere, the light rays emitted from the light cover only a smaller fraction of the sphere's surface. Having exactly half the sphere directly lit from a single light source is absolutely impossible (only possible in 3D rendering packages using directional lighting, where the light rays are all parrallel to each other in an infinite wide plane.) The closest we can get to having a half sphere lit by a light is to have this (immensly powerful) lightsource billions of miles away (ie. the sun), and even then, the rays are still not perfectly parralel.

The distance of the light source affects shadows in the same way, where a light close to an object will project a WIDE shadow while one far away will cast a narrower one, as shown in Francis' diagram above. By tracing rays, all the lighting secrets are revealed.


[This message has been edited by Frost (edited May 27, 2000).]

[Nex]

hmm I'm really lost somehow.. I tried to get it all right but somehow I know it still isnt' good. I've worked on this now 2 hours..



I'd be very happy about:

tips for shadow value / shadow look (core shadow etc) / shadow border (when smooth, when hard) / cast shadow construction / difference cast shadow and object shadow.

This all must sound really stupid to someone who had art training... but what the f**k I will get better than you all

(after drawing another 3,5 Million cubes)


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- Nex

http://on.to/nex

[This message has been edited by Nex (edited May 27, 2000).]

[tzekin]

Spooge, thanks for your useful comment. I'm working on my second try right now.I hope the errors that will be in my second try will be explained so well too.

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---a.tzekin
tzekin.iloveimac.com

[Trance-R]

I made one in Flash. With steps showing how I did it too.
Shadow Tracing

BTW, I have a question.
How do you draw a rotated cube? And the shadow a cube casted on another next to it(the one Craig did on page one). Please explain with some sort of visual aid in technical diagram. My English is poor. Thanks!

[This message has been edited by Trance-R (edited May 27, 2000).]

[Francis]

Here's a little diagram showing some principles of shadows cast onto another object. There's a lotta lines, but hopefully this makes a little bit of sense.

For clarity, I've omitted the construction lines for the cube, and I've only constructed the shadow for the cube on the left.

This is mostly the same as the previous diagram I posted. The difference here is that the shadow falls on the vertical surface of the other cube. Again for simplicity, I've made the cubes parallel to each other, so that the faces of one cube are parallel to the other.

The key here is that the vertical line "a-b" of the left hand cube creates the shadow line from point "b." (The one along the ground, following "b-bb".) It stops at the base of the second cube.

Now if you imagine line "a-b" as a stick in the ground, it would cast the shadow "aa-bb" on the second cube. The point "aa" is the critical one, from which you can construct the rest of the shadow - the height of "aa" comes from a line originating from the light source and passing through point "a".

Because the top edge of the shadow is caused by the top edge of the left hand cube, it goes to the left hand v.p. rather than the light or shadow v.p. (In general, shadow edges caused by verticals go to the shadow v.p., and shadow edges caused by horizontal edges of the cube go to the "normal" left or right v.p.) The short diagonal edge of the shadow cast on the face of the cube starts at the bottom of the face, where it meets the ground, and then travels up to the point "aa" you determined earlier.

One or two other notes - my cubes aren't really cubes. I eyeballed the sides when I constructed them, rather than constructing them from a plan view, which is one way of getting a true perspective representation of a cube. I can post that later if anyone is interested.

Also, because I've moved the shadow v.p. down on the page until it's right next to the cubes, I've basically created an artificial point light source right next to and above the cubes, like a tall floor lamp. This creates a different situation than in my previous diagram, where the light source was far away. Just so you know.

Again, if I goofed anywhere, I'd be happy to knwo about it.

Thanks for your time.



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TeamGT Studios

[Francis]

I forgot to mention that the green lines correspond to shadow construction lines for the first cube, and the light red lines show the construction lines cast on the second cube.

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TeamGT Studios

[Joachim]

ouch, here's my first go at it.
I don't want to start making exscuses, since I find this quite difficult in the first place :/
So I guess it's time to duck and cover



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Joachim
web: http://home.sol.no/~jbarrum/

[This message has been edited by Joachim (edited May 27, 2000).]

[nori]

My cubes are COOL. OK? cOOL. Any advice?

[Gimbal]

At first this seemed like a challenging task: to render two white, matte finish cubes on an infinite, matte white plane with a single light source. But after I contructed a couple cubes and tried to think of how to render them I realized it will be far more then challenging. For me to get this to look somewhat right will take a very long time. To get it picture perfect...well, I can dream, can't I?

I have some questions (some have already been answered in previous posts) and I know some of them have already been asked but these are some of the things I was wondering:

1- Constructing a cube that isn't aligned with the 2 perspective points. My attempt was to draw a square on the ground(in perspective)and use it to draw a circle (ellipse) within it. Then, by eye, I made an 'X' in the circle aligned in the direction I want the cube to be in. I extended the two perpendicular line out until they met up with the eye-line and where they intersected would be the two points I would use to contruct the cube.
I would draw up a diagram of what I was trying to describe but hopefully there will be no point in doing so as there is a simpler/more accurate way of doing this...right? Anyhow, It comes out looking OK but then comes the next question:

2- Is there another way to make sure the two cubes are on the same level surface besides using the ol' Mk-1 Eyeball?

More importantly, what is the best book I can use to learn these basics of perpective drawing so I'm not bogging down the whole learning process for everyone else? I know a few were mentioned earlier but I was wondering which one is best for explaining shape and shadow construction, rotation etc.

I'd like to thank everyone involved here on this forum for providing such a wealth of information and oppertunities to learn. This reminds me of martial arts training and what Bruce Lee said about it: "Before I studied the art, a punch to me was just a punch, a kick was just a kick. After I'd studied the art, a punch was no longer a punch, a kick was no longer a kick. Now that I understand the art, a punch is just a punch, a kick is just a kick."

One day I hope these simple cubes become simple again.



[This message has been edited by Gimbal (edited May 27, 2000).]

[Trance-R]

Thanks Francis!!!
That diagram and description helped me out alot! Have you all seen my Flash shadow?! I spent quite some time on it. Please look. http://dencity.com/trance/shadow.html

I did this before I read Francis's post. I might do another one... the small box is not close enough to the big one to get any shadows from the big one.

[This message has been edited by Trance-R (edited May 27, 2000).]

[AliasMoze]

Gimbal, first of all, very appropriate name for these drawings.

Second, I did a search on Yahoo and found this link for you:
http://www.saumag.edu/art/studio/chalkboard/draw.html

Don't worry about bogging the exercise down. Personally, I do line work (as does Mozeman). This painting stuff is almost all new to me. And, even if it weren't, the quest for technical perfection is a worthy challenge. Heck, even Spooge made mistakes in his image. I'm just glad Fred has taken over this portion. He has/does teach professionally, so he knows how to get this stuff across and spot our errors. So we all get a great lesson for free. Long live the internet!

Anyway, hope the link helps out.

[sydneyshan]

Good link, useful aid!

Thanks for your comments and encouragement Spooge- will be working on my second, third & forth attempts soon =)
Have three assignments due tommorrow, so...soon.