# Perspectival Shadows cast from Before

Last time, we considered the method of showing a proper shadow cast from a light source which is behind the viewer.  This lesson today will demonstrate the opposite situation, where the light source is before the viewer.

Andrew Loomis in his book Successful Drawing shows us the method of solving how to draw shadows in proper perspective.  The first point which needs stating is a concept hinted at from 2 postings past, which I hope to make concrete by the end of this lesson.  The aforementioned idea is that if the light source is Behind, the angle of light is below the horizon.  When the light source is before the viewer, the angle of the light is above the horizon.  Hold onto this thought, and I will review it at the end of the lesson, where I am sure it will form an integration for you.

Here are the steps for casting a perspectival shadow from a light source which is before.

1. Set up your horizon and the object using proper perspective.  Establish the Vanishing Points for the object’s sides, and draw the appropriate angles.  Draw the guidelines for the perspective on a separate layer of vellum or digitally, then remove the guidelines when the object is perspective. Save the layer.
2. Since the light source in this exercise is before the viewer, it is proper to next establish the position of where that light is coming from specifically.  This should be done with precision within the layout phase of your drawing.  Even if the light is not going to be within the boundaries of your finish crop for the illustration, you must lay it out with exact placement, or else your shadows will appear unconvincing.  Drop a line vertically down at 90 degrees from the centre of the light source to the horizon line.
3. The point where the vertical line crosses the horizon will be the VP of the shadows. This is a crucial step, so pay close attention to it.  As a rule, the Vanishing Point of shadows is directly below the light source when the light is cast from a Before placement.  The blue lines below represent the projection for the  Shadow VP.  Please not that these guidelines cross through the corners of the object you are drawing, laying on the ground plane.
4. Next we will cast the lines of light, which will fall like a triangle from the light source.  Each corner of the object you are drawing will interrupt the light, but the perspective you have chosen may conceal certain corners.  In this drawing there are 3 corners which will cast a shadow we can see, so there will be 3 lines.  If your object and perspective yields more corners which will cast a shadow, use the appropriate amount of lines.  Note how the light lines emanate from the centre of the light source, not its perimeter.  Cast the light lines further than where the Shadow VP lines lay on the plane.
5. Now, turn on the layer with the original perspective lines showing.  These perspective lines will give us the other half of the information we ned  regarding where the shadow’s perimeter will lay.
6. Where the red light lines cross either the blue Shadow VP lines or the black object perspective lines with demarcate the corners of the cast shadow your object will make, given the perspective you have chosen, and the placement of the light source.  I have numbered these 1-4.  Numbers 5 and 6 are the points where your object touches the plane it rests on, and from these points the shadow will originate.
7.  Outline the cast shadow perimeter, then fill it in with the value appropriate for the light intensity you are describing.  The darker the shadow, the brighter the light.  Add half-tones to the shaded sides of the object (the sides facing away from the light) Flat planes have even shading, curving planes will appear as a gradation.
8. Remove the guidelines to reveal your illustration of a properly done shadow, in perspective, with the light source before the viewer.  Congratulations!

As a last comment, think back the the idea of the angle of light above and below the horizon which I mentioned at the beginning.  If you think about it, it is natural to recognize that the angle will come from above when the light is before, because when standing on the earth, you perceive the horizon above you.  If the light is coming from behind, the angle must come from below for the same reason.  It is possible, tho rare that one’s point of view can be distorted, such that the horizon is perceived as below you.  This could occur if you are inverted or suspended in the air.  Such points of view will break this rule.  Luckily, there are limited calls for illustrations of that type.  I will cover such considerations at a much later date, due to their peculiarity.

There are many more subtleties related to cast shadows, but I believe I will go onto showing organic cast shadows in perspective next week.  It will be a difficult one!

The method of placing a shadow into perspective is an important skill to have as an illustrator.  There is a method which Andrew Loomis shows us in his book called Successful Drawing.  I will outline it here, following a short preamble.

When we look at an object on a plane, we see it in perspective, as it appears from our point of view-or our perspective.  The angles recede to a point on the horizon called the Vanishing Point, which always changes depending on where the viewer is situated.

The shadows cast by an object sitting on a plane will also have a vanishing point, but it is relative to the direction the light is being cast, as well as to the viewer’s point of view.  Working out the perspective the shadow takes, relative to the viewer is a factor of drawing the primary object into proper perspective- if you have done this, the P.O.V perspective of the object’s shadow will follow suit.  This is only the first consideration though, as stated above, the shadow also has to fall relative to the direction the light is being cast.

I will demonstrate Loomis’ method of solving this problem.

1. First, as will all drawing, one should set out the horizon line, and decide on the vanishing point, or points if the perspective is 2 point or more.  Here is a sample with 2 Vanishing Points, labeled V.P. below.
2. Once the VPs are set up, draw lines going to them, as per the shape you are drawing.  It is important to draw a geometric shape at this stage, then convert it to an organic shape later once the perspective is worked out, since it is easier to solve these issues geometrically.   Here I intend to draw a box shape.
3. Here is the box shape drawn in using the two VPs.
4. Now, once you have decided on the object’s perspective, it is time to decide on the next major piece of information which an illustrator needs, in order to create a convincing picture; the direction of light.  You should be aware that this stage is not regarding the angle the light is falling from, just whether it is coming from the left of the object or the right.  The angle is determined later.  For this image, I chose the light to be coming from behind-right. (NB. Last posting defined the direction terms Behind and Before as being relative to the viewer, not the subject matter.  If the light is behind the viewer, the direction line comes from below.)
5. Light travels in a straight line, so this direction line you set is very important; it will now show us where the VP of the shadow will be, relative to the light.  As stated before, the shadow’s perspective relative to you will be taken care of on account of the shape you have drawn already.  Whichever perspective that shape is in will define the POV perspective the shadow takes, as we will use the corners of the shape as reference points for the shadow.  When you cast the line the light is travelling at, the point where it crosses the horizon will be the VP of the shadow.  Bisect the horizon with a vertical line where the Shadow VP lays.
6. Once the vertical line bisecting the Shadow VP has been established, we can now determine the angle of the light.  The vertical drawn will act as our gauge to keep the angle constant.  Choose the most prominent corner of your subject matter, and at an angle of your choosing, cast a line which goes through the prominent corner, as well as through the vertical line you drew in step 5. This will be the primary angle of the light.
7. Since there are more than 1 corner which catch the falling light, we need to determine where that far, and hidden corner of the box would be.  This is done by again casting lines to the 2 original VPs we chose for the box.  Cast your lines to determine the back side of the box using the corners which you can see on the right and left.  I used the blue lines to demonstrate this below.
8. Once that is done, describe the back side of the box, using dotted lines, and make a note of where the corners are.
9. The second upper corner of the box, hidden by the side which faces you is also within the purview of the light which is falling.  You need to now account for the angle of the shadow it casts, using the first Angle of Light you decided upon.  At the crossing point of the Angle of Light and the vertical line which bisects the Shadow VP, draw up again, crossing through the new, hidden corner you just solved in step 8.  This will tell you how the shadow falls relative to that corner, and the angle of light.   This new angle line I have drawn below, it is the thinner of the two lines describing the Angle of Light.
10. Now, using the heretofore unmentioned bottom corners, cast lines from both the near and far corners, going to the Shadow VP.  These lines will give us the side edges of the cast shadow, and they are represented in dotted blue below.  The red Angle of Light lines show us where the shadow will end, in a straight line between the two crossing points of the 2 dotted blues, with the two reds.
11. Please note, I marked an X where the far corner of the shadow would appear (at the crossing point of dotted blue and the thin red Angle of light line).  You can see that the X is within the body of the subject matter, indicating that the back corner of the shadow cannot be perceived by a viewer standing at the perspective we chose for this object.  This is what I was meaning by saying that by properly drawing the subject matter in perspective will take care of the shadow’s P.O.V perspective.  Here is the X marked in the drawing below, with pink lines outlining the box’s shadow which such a perspective and angle of light would cast.  The far corner of the shadow  is behind the box.  The shadow extends from the bottom of the subject matter where it touches the plane.
12. Finally, remove the guidelines and fill in the shadow with a dark tone, relative to the brightness and quality of light you would like to represent.  I kept the angle of light lines active, so you can see how the corners of the shadow will meet them.

Thank you for reading this week’s posting.  Next week I will show you how to cast shadows in perspective from a light source which is Before the Viewer.

Best wishes.

# 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.)

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.

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.

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.

• 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.

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.
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.
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.
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.
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.
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.
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.
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.
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.

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.

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.