3D chalk art is created by intentionally distorting images. That is the first principle. Anamorphosis by definition is "a distorted image which, when viewed from a certain angle, looks correct". So, the 3D illusion you create will look different from another point of view. It will look different because it is intentionally distorted by you, the illusionist, to fool the viewer into thinking it is 3-dimensional.
We usually take for granted the illusion depth in the flat images we see all around us. But there really is no depth there at all. They are flat. How is the illusion of depth created? It is created by drawing lines at an angle and making things get smaller toward what is called the "vanishing point", a point on the horizon where things seem to disappear. Artists figured out how to fool the eye into seeing depth on a flat surface. But it took some time and experimentation before they finally got perspective right. It did not come naturally.
Artists who were commissioned to create works of art that were to be viewed from more unusual angles had to think of ways to make their works look correct from those unusual viewing angles. Looking at art on the ground is very unusual. So the artist compensates for this unusual angle. Art created on the ground looks big at the bottom and small at the top. This error is caused by perspective. In this lesson, we will see how perpective is used to create a 3D illusion in chalk. We'll use the alien coming up out of the ground in the photo as our example. This lesson will show you how to do anamorphic projection.
The 3D illusion is most effective if you take a photograph of your finished chalk piece. When you see 3D chalk art in real life, the illusion is not as amazing as it is in the photos you see floating around the internet. In fact, it will appear quite distorted! The photo is the final, necessary step in the process.
To complete this lesson you will need...
1 pad 11"x 14" drawing paper.
A few sheets of 8 1/2"x 11" multi-purpose paper.
Yardstick
12" inch ruler
Pencil/eraser
Protractor
Compass
1 pad 8 1/2" x 11" vellum or tracing paper (vellum recommended)
Drafting tape
Scotch tape
A basic knowledge of drafting, perspective, geometry, and drawing will be helpful in this lesson.
Figure 1 |
The space we have to create our 3D chalk art is 6' x 8' feet.We are going to create a scale drawing of our working area and our chalk drawing. It will be a perspective drawing. Let's make the scale 1 3/4" inches = 1' foot. The horizontal line at the bottom of the drawing represents the bottom edge of our chalk drawing. It also represents the ground. It is composed of 6 units. Each unit is 1 3/4"inches in length. The drawing sheet is 11"x14" inches. The vertical line in the center of the drawing is 5 1/2 units long (9 5/8 inches). This vertical line represents an average viewing height of 5 1/2 feet above ground. The horizon is always at eye level. Draw the horizon parallel to the ground and mark the intersection of the horizon with the center line VP (vanishing point) as shown in figure 1. You can always click on the figures to enlarge them. |
Figure 2 |
Next, extend the bottom edge of your drawing 2 units to the left as shown in figure 2. You will need to attach additional sheets of paper. Extend the bottom edge of your drawing 5 units to the right. This represents the distance between the observer and the bottom edge of your drawing. Create a point of view (POV) 5 1/2 units above the ground. Using a yardstick, intersect points POV and ground units to create reference points for the horizontal lines in the grid. It is not necessary to draw the intersection lines, only the intersection points shown as red dots in the drawing. Try to imagine the blue lines in figure 2 as lines of sight from the observer looking down at your drawing. |
Figure 3 |
Connect points VP and ground units to complete your perspective grid as shown in figure 3. This is what a 6' x 8' foot grid would look like to someone standing about 5 feet away from it at a height of about 5 1/2' feet. |
Figure 4 |
Draw the alien on the perspective grid as shown in figure 4. In this example, the alien is drawn on a new sheet of vellum to protect the grid from getting erased during the design process. We need our grid to remain perfectly intact in order for the illusion to work. If you try to redraw the grid after it has been erased the lines loose clarity. Try to draw clean lines keeping shading to a minimum. At this stage, it is important to be able to clearly see the outline of the design. Try to draw in perspective to match the grid as closely as possible. Notice that the unused portions of the grid do not need to be drawn.
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Figure 5 |
Place some vellum on top of your drawing. Make it enough to create a squared version of your grid. Square the grid as shown in figure 5. It helps to draw the outer perimeter first, measure 1 3/4" unit marks along the perimeter then connect the marks. The squared grid represents 1' x 1' foot sqaures you will draw on the ground in chalk.
Now before we proceed, we should consider the viewing angle and perspective. We have already established that our observer is 5' feet away from our work of art (POV) but now it is time to create an anamorphic projection point that will approximate the phenomena of parallax that occurs as a result of having two eyes.
To demonstrate parallax, hold your thumb out at arms length, look at your thumb, close one eye and observe where your thumb is in relation to some background object. Now keep your arm extended, close the eye you are looking through and look at the same background object through the other eye. Notice how your thumb seems to shift horizontally in relation to the fixed background point. Also notice that the greater the distance to the fixed background point, the greater the shift. Parallax projects out in a beam like a movie from a projector. |
Figure 6 |
Without moving the eyes, human range of vision is about 120° degrees horizontally. Moving the eyes from side to side horizontally increases that range to about 180°. Since our artwork will be on the ground and flat, we won't concern ourselves with vertical range of vision. Due to parallax, our anamorphic projection point ends up in front of our POV and not directly on it. Using a protractor and compass, we will create an anamorphic projection point for our drawing similar to the one shown in the example in figure 6. The grid size in figure 6 is different from ours but the principle still applies. A horizontal line is drawn at least 5 grid units long intersecting POV (figure 6). An arc is drawn with radius 2.4 grid units. The arc radius is 2.4 units because the average distance between human pupils is about 2.4" inches. Marked are 30° points along the arc at the West and East ends. The points are connected. The intersection of drawing vertical center and the 30° horizontal is the projection point (PP).
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Figure 7 |
The illusion of 3D in chalk art (or any 2-dimensional artform) is achieved by intentionally distorting images but the method of distortion is an exact science and not guesswork. Figure 7 is an example of using the projection point to accurately distort simple geometric objects in a drawing. Lines are drawn radiating out from the projection point. The lines are used as reference guides for angular distortion of the objects with reference to the grid. The lines are also used as spacial reference points as they intersect grid lines.
Figure 8 is a photograph of the drawing in figure 7 photographed
from the correct viewing angle. A real cylinder is placed on the drawing to show how adding real-world objects to a scene can greatly increase the 3D illusion as illustrated by adding the screaming youth to the photo of the alien coming out of the ground scene. In the figure 8 photo, notice how the projection lines seem to be coming from below the drawing surface and not from the drawing's edge. This is a very interesting illusion. It is the basis of 3D chalk art. Shading in the drawing dramatically increases the illusion.
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Figure 8 |
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Figure 9 |
Refering to figure 9, find the projecton point for our drawing. 1. Place the POV 5 units (8 3/4" inches) along vertical center of the drawing from the bottom edge of the drawing remembering that our photo will be taken 5' feet away from our chalk drawing edge. 2. Draw a horizontal line through POV at a right angle to drawing center. Make the line 5 units long. 3. Using a compass draw an arc slightly under 2.5 units radius. 4. Using a protractor, find the 30° points on the arc on the East and West ends of the arc. 5. Intersect a line from 30° points on the East and West ends of the arc with vertical center of the drawing, mark projection point. We now have our anamorphic projection point. This point will be used to project key elements in our perspective drawing onto our squared grid just like the example given above.
Accuracy is imporant at this stage. Take your time and make sure all your measurements are correct. Accuracy of drawing and measurement are key to a successful 3D illusion. |
Figure 10 |
Using a yardstick and the projection point, find key elements in the perspective drawing, readily identifiable reference points, and project them onto the sqaured grid. Locate portions of the design that intersect grid lines and make them correspond to the squared grid. For example, the corners of the alien's eyes are used as key reference points for projection (Figure 10). The grid is used to tell where the top and bottom of his eyes should end. Imagine what a movie would look like if instead of the screen being perpendicular to the projector, it were tilted at an angle away from the audience. The image on the screen would appear to become more distorted as the screen tilts away from the audience. That is how you have to draw in order to distort the image to compensate for the unusual viewing angle. Less distortion close to the audience, more distortion away from the audience.
It will feel very unnatural to draw like this at first, but after you have done a few, you will see how the distortion works and it will feel more natural to draw this way the more 3D chalk pieces you do.
When you photograph your finished chalk piece, mark a point on the ground that corresponds to the POV in your design (5' feet away in our example). Shoot from that point. The POV, not the projection point. The projection point is ALWAYS in front of the POV. Shoot from POV. Add a person interacting with your chalk piece to make the final photo FANTASTIC! |
Figure 11 |
Figure 11 shows the alien's antennae projected. He also has a few pieces of the ground he came up from under resting on his head.
It's important to note that holes in the ground, such as the one our alien friend is rising up from are drawn circular on our squared grid. Any openings in the ground of a 3D chalk piece are drawn circular. Perspective creates the oval shape that will be seen. Refer to figures 12 and 7 above.
Figure 12
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Figure 13
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Figure 14 |
Figure 15
Following figures 13 and 14, complete the drawing. Use the projecton point for every key element in the drawing. Remove the perspective drawing from under it and make an 8 1/2" x 11" copy to take with you to your chalk art site. Darken the grid if needed.
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