Are there rules for drawing shadows? I know there is a way to draw lines that I have heard about to extend an object on the basis of the light source to make an acurate shadow. But that seemed pretty complicated, although I only heard of a description of the article and did not get to read the original. I also know that the shadow takes on the shape of the object that cast it. But still there must be some tips. Some basics I am missing because they never turn out right. Any suggestions would be appreciated.

Yeah, shadows are what you make of them. Without a reference photo, they can get as technical as 2 point perspective, sometimes even three points.

What follows is my own research on light sources, please correct me if I'm wrong, I'm part way through a painting that relies on these principles and rules being correct.

First, draw your object from a birdseye view (plan), with the lightsource, make sure they are roughly to scale.

Decide if your light source is small (narrower than the object, eg. a bulb, torchlight, or candle) or large (wider than the object eg. fluroresent, window, or the sun).

This decision will decide which of the two techniques you will use.

1) Small light source (ref fig 1)
Draw a line from one edge of the lightsource to the same corner of the object. Then draw a line from that edge of the lightsource to the opposite corner of the object.

Repeat for the other side of the lightsource.

This should give you two slender triangles on each side of the object. These are what I have named the illumination paralax transition, or the shadow fuzz. Basically, this is the area where the light fades to shadow. As the triangle moves away from the object, the gradient grows slower. Thus, where the light first meets the object, the shadow/light line is sharp, but diffuses as it moves further out.

2) Large light source (ref fig 2)
Draw a line from one edge of the lightsource to the opposite corner of the object. Repeat for the otherside of the lightsource.
Now draw a line from one edge of the light source to the furthest corner on the same side. Repeat for the other side.

This technique gives you 2 irregular diamond shapes on each side, which require very slight shadows, as less than half of the lightsource shines here. Behind the object will be an hourglass shape, with two triangles pointing at each other. The triangle closest to the object is the darkest shadow. I havent figured out a way of calculating the paralax transition (shadow fuzz) for this, so for now just do it optically (what looks right).

This gives you a general idea of how to work out difficult lighting situations. You can use excactly the same treatment for multiple objects, just keep drawing lines to the same and opposite corners.

Of course, you can get as technical as you want with this, so far this just gives you a plan view on the lighting, which you can take as a rough guide to put in your pictures. However, if you want to get REALLY tricky, I can explain how 2 use the rules of perspective to accurately transfer it into a 3D setting.

Also, you need to take into account the strength and temperature of lighting, however thats another study altogether

This might help let me know if any good?

http://www.geocities.com/~jlhagan/lessons/mainmenu.htm


http://www.mmwindowtoart.com/page2a.html these are Free art lessons you have to look though them to see what u need


http://www.teachartathome.com/Shadowsandshading.html

http://artsillustration.com/shading_tips.htm

http://artsillustration.com/shadingsteps.htm

You've gotten some good advice and links here Calvin, but let's bring it down to simple levels. Why don't you post the image you are trying to render and we can see what problem you are having with the shadow exactly?

Shadows depend so much on the light source and its angle and whether the object has planes or is curved.

There is a method to draw the shadows in perspective but I've never used it. My drawings aren't that technical as a rule. 3lansir's the perspective guru here, he can guide you well through this.

Hey there Calvin,
Being a draftsperson, using shadows in my work was important, however most of the work was done as per 3lansir statements. I have found however, that art takes a bit of a different viewpoint...
I have found that one can 'fool the eye' with very simple shading in the opposite direction of the light source, so for example, if the light is coming from the top right, then shadows will have to drift to the left. I have found as well that shading heavier closer to the object gives more 3D effect. Notice one of my pics in the gallery...http://www.drawspace.com/forums/uploads/1159384266/gallery_17777_482_25900.jpg
The light source is coming from the left, causing shadow under the mane to the right. Also notice that the shading is heavier closer to the source.
Another consideration is the terrain that the shadow is covering. 3D effects can be very convincing if you attempt to follow the terrain, the ups and downs (keep in mind that an 'up' forshortens the shadow and a 'down' lengthens it that much more). Now in creating the shadow, you really dont have to be that concise, general shape and size is fine, as the eye will tell the brain what to see, especially if your piece is 'busy', full of items and objects that will break up the shadow. What is important however is maintaining consistancy with direction based on your light source.
Hope that helps!!
Cheers.

PS I found another useful link...http://www.dummies.com/WileyCDA/DummiesArticle/id-1740.html
Please ignore the site name, as I found these series extremely useful for my students.