Cast Shadows: Behind and Before

Cast Shadows: Behind and Before

When you are drawing shadows, there are a couple of rules which need to be remembered in order to create a natural looking illusion of light. Fortunately, Andrew Loomis helps us negotiate these points in his book Successful Drawing.

The first rule he indicates is an observation regarding the two location choices of light source when representing cast shadows; that is, a behind light source or a before light source. Behind and before are designations of where the light source is in relation to the viewer of the picture, not the subject.  Examine these samples I’ve drawn for you below.

In the picture of the Ogre below, the primary cast shadow on the ground plane shows us that the light source is behind you– the viewer of this picture.  The ogre’s actual body is interrupting the direction the light is falling, and hence, it casts a shadow behind.  Notice that cast shadows which are even somewhat to the side of the subject are still considered the result of a behind light source.

If the light source is behind, the shadow will fall behind.

(NB. In this drawing there happens to be two light sources, as you can see in the secondary small cast shadow under the ogre’s chin, and likewise below his hands.  For this matter, we are regarding only the large cast shadow on the ground.)

Screen Shot 2019-02-06 at 3.24.47 PM

 

 

This drawing is considered to be a light source which is before the viewer.  One can tell on account of the fact that the shadow is falling between where we the viewers are, and the subject matter of the lady, as she sits on the plane.  One can imagine the sun above her, in the sky, before where you are standing, looking at this lady.  The sun before you, therefore constitutes a before light source.

If the light source is before, the shadow will fall between.Screen Shot 2019-02-11 at 6.45.42 AM

 

Now that the terms before and behind have been established, there are several rules about casting shadows from before and behind light.  Here are  Loomis’ rules about drawing cast shadows.

  1. If the light source is behind the viewer, the angle of the light comes from below the horizon.
  2. If the light source is before the viewer, the angle of light comes from above the horizon.
  3. If the light source is before the viewer, put the shadow VP on the horizon nearby, below the light source.
  4. When the light source is before the viewer, the angle of light is the nearest of the 3 cast shadow considerations;
    • position of light source
    • angle of light
    • VP of shadow on the horizon
  5. All shadows radiate from a point on the ground directly below the light source.  This point is the shadow vanishing point (SVP)
  6. All shadows within a drawing recede to the same SVP.
  7. The length of shadow on the ground plane is determined by the angle of light.

 

That is a lot to digest, so at this point, it may be of use to my readers to think on these concepts for a while, before diving into how one actually draws before and behind light source shadows.  Next week, I will demonstrate that process, as well as how to cast shadows of organic shapes, like those in my samples above.

Thank you very much for your continued interest.

Bye for now.

 

Types of Light, Cast Shadows & Perspective of Shadows

Types of Light, Cast Shadows & Perspective of Shadows

Greetings,  this week we will be continuing our discussion of Andrew Loomis’ book Successful Drawing, and considering types of light and how to represent shadow.

He begins by indicating that there are two main types of light.  These types are

  1. Direct light
  2. Indirect light

Loomis emphasizes that the decision to treat a scene or subject which an artist is attempting to represent, begins with choosing one or the other of these 2 types.  It is important to choose only one of these types, and to stick to it because the treatment of light in a drawing is what gives the art an impression of consistency.  The absence of light could technically also be a 3rd category, but Loomis doesn’t even mention it because the drawing would be pure black.  Any small amount of a subject matter, regardless of shadow depth around it, is an effect of Indirect Light treatment.

With the casting of light, comes the Cast Shadow.  Cast shadows are the areas of a drawing where your subject matter interferes with the direction of light, and that interruption shows on another plane in the form of a shadow.  The shadow you see of yourself on the ground on a bright day is a Cast Shadow.  This is different than the type of shadow called Shading; ie. how lights and darks fall on an object, as discussed previously. Although one could consider the Shading on the dark side of the moon, to be a shadow which is cast by its lit side, such  reasoning only confuses the issue.  It is better to think of Cast Shadows as those shadows which an object throws onto another plane or object.

  • Cast Shadows: the interruption of light caused by an object, translated as darker value, appearing on a secondary object.
  • Shading: the translation of how light falls on a specific form, related to that form’s general shape.

When representing Cast Shadows, the artist must consider 3 factors.  These factors are as follows:

  1. position of light source
  2. angle of light
  3. the Vanishing Point (VP) of the shadow on the horizon.

Each of these three must be understood in order to place a Cast Shadow convincingly within the context of the scene an artist is attempting to represent.  Loomis shows us how to do it.  He indicates the best way to cast the shadow properly is to alter the plane of your subject matter which is facing the light to a square.  Draw this square properly extending to the VP.  Then, using the line the light falls at, project a central line and lines from the corners to the angle of ground you have your subject matter sitting on.  This will show you how a square casts a shadow.

Example.  IMG_9277

 

Here are the steps.

  1.  Contour draw your actual subject matter with light pencil.  Decide where the light is hitting the object and the angle it is coming at.IMG_9269
  2.  Draw a line of the light direction, and approximate the “Illustrator’s Bump” (see last post) which will show at the transition from light to half tones.  The line of light will bisect the Bump.IMG_19270
  3. Draw a flat square shape, representing a simplification of the plane of your subject matter which is facing the light.  Set the square to the VP which your actual subject matter is related to.  Cast diagonals from corner to corner of your new square to reveal the centre.  I do this on a separate layer to keep the original artwork clean.  NB> the line of light is not related to the perspective lines.  They are at separate angles.IMG_9271
  4. Project the edge of the square onto the ground at the angle you imagine your subject matter to be sitting at.  This angle goes to the horizon again, at a secondary point, where the VP of the shadow points.  IMG_29274
  5. Cast a line parallel to your light line off of the top near corner of the square. Let it cross the angle line you drew in step 4.IMG_39274
  6. From the bottom near corner, send a line to the VP.  Likewise do the same from the point where  the top light line from step 5 bisects your ground angle.  Lines to VP are pink, Light lines are green. The pink perspective lines show you the top of the projected square.  IMG_19274
  7. Use the points of the square to draw the other side of the projected square, bisecting the top perspective line you just drew.   Aim this line to the VP of the shadow used in step 4. This line will establish the mostly hidden other side of the projected square. The yellow line represents the opposide edge of the projected square.IMG_y19274
  8. On another layer, draw lines from corner to corner on the projected square, and where they cross, draw a third dotted line parallel to either side.  That dotted line is the centre of your projected square.  These guides will help you draw the projected shadow of your original subject matter.IMG_9275
  9. Using this information you worked out, go back to your original contour drawing of the shape, and add the proper modelling of form in light, as well as the Cast Shadow laying on the ground beside. Don’t forget the Illustrator’s Bump, where the shaded side meets the lit side.

IMG_9276

Next week, we will continue with some more information on how to use Cast Shadows in perspective.  Thank you very much for reading.

 

 

 

 

 

Light on Basic Forms II

Today, we shall continue the investigation of how Andrew Loomis unpacks the principles of light and its effect on forms.  Following the 4 Laws Loomis provides for us, as outlined in the previous posting, he continues with some very useful particulars regarding light and shadow.

The first of these particulars is the phenomena Loomis calls the “illustrator’s hump”, that is the observation of how on a curving surface, the darkest part of the shadow appears closest to the lightest part.

This seems counter intuitive, as per the idea that the furthest point away from the light source must be the darkest point, until one realizes that light also reflects. The darkest part shows at the point of change from light to dark, on account of the fact that a certain degree of the cast light reflects back from the surface which the lit object is laying on. This reflected light, or other ambient light partially illuminates the object.  This phenomena does not occur on the Moon, because the Heavenly Bodies are objects which are actually suspended in space, and there are no planes below them, which could reflect the light back onto the dark side.

A further observation about the ‘illustrator’s hump’ is that the shadow which the object casts begins where the “hump” on the surface begins.  Tracing a light line in the direction which the light is falling will show you where to put the edge of the shadow which the object casts on the plane it sits upon.  For clarity, please refer to the illustration I have done, just below.

 

illustrator's hump

Further particulars which Loomis outlines in this section are some rules on how to think of the principles of light and shadow in regards to the angle the subject sits at, relative to the light source.  If one thinks of angles, rather than the puzzles of how to render light on a surface, many potentially confusing traps can be avoided.  He provides us with the following principles.

  1. An object between the viewer and the light source is in full shadow.
  2. If the light is behind the viewer, the lit object is cast in full light, as in the effects of a flash bulb.
  3. If the lit object is placed at right angles to the viewer’s position, as well as to the light source, the object seems to be half in light and half in darkness.
  4. If the lit object is placed in a quarter-turned position, the resulting effect is either 3/4 light and 1/4 dark, or vice-versa.

Loomis further indicates that quarter turned positions present a more satisfactory effect, as either light or dark then dominates the subject matter.  This appears more appealing to the viewer than an equal division of light and dark.

Finally,  there is concession which Loomis gives to certain cases where an even dispersal of light on a subject is appropriate, for instance he indicates that full-frontal light is good for posters and poster effects, such as in the work of Norman Rockwell.

Thanks again for reading, next week we will cover the 2 main types of light, cast shadows and how to represent shadows properly in perspective.

Cheers.