Build a Better Cast Shadow

What to Know

  • Identify an imaginary light source and cast the shadows opposite the light source.
  • Duplicate the object. Skew and stretch the duplicate opposite the light source. Fill with black or gray and apply Gaussian Blur.
  • Attach the cast shadow to the base of the object and skew the rest away from the object and light source.

This article explains how to build a better cast shadow by identifying a light source, duplicating an object, and anchoring the shadow to a surface. It includes information on making cast shadows part of the background.

How to Add Perspective and Dimension With Cast Shadows

Like drop shadows, cast or perspective shadows add interest to elements on the page. They work to anchor elements on the page, tie components of a composition together, and add a touch of realism — even when used with unrealistic objects and clip art.

Cast shadows add perspective and dimension. The first step is to identify an imaginary light source.

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Base Cast Shadows on Imaginary Light Source

Lifewire / J. Bear

Cast shadows form when an object blocks a light source. The shape of the object is projected in shadow form across surfaces opposite the source of the light. Generally more complex to create than drop shadows, cast shadows are still a relatively simple way to enhance text and graphics in page layouts and give a three-dimensional appearance to a flat piece of paper.

Unless you are intentionally creating a fantasy world that breaks the rules of light and shadow, cast your shadows using a reasonably placed imaginary light source based on reality.

Cast your shadow opposite the light source. Light sources that shine down almost from directly above tend to create shorter shadows. Lights more to the side of an object make longer shadows. A bright beam creates a more pronounced shadow while low light or diffused lighting results in softer shadows.

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Create Quick & Easy Cast Shadows

Simple cast shadows are black or gray, somewhat distorted duplicates of an object
Simple cast shadows are black or gray, somewhat distorted duplicates of an object that extend from the object across a visible or invisible surface.

Lifewire / J. Bear

The easiest cast shadow:

  1. Make a duplicate of the object.
  2. Rotate, skew, stretch the duplicate opposite the direction of the imaginary light source.
  3. Fill duplicate with black or gray.
  4. Apply a slight blur (a Gaussian Blur works well).

A real cast shadow tends to be darker and more sharp-edged near the object. Further from the object, less light is blocked so the shadow becomes lighter, softer. A more realistic shadow is possible by using a gradient fill or fade from dark to light then selectively blurring the shadow -- more blur further from the object casting the shadow, less blur near the object.

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Anchor Objects to a Surface

Drop shadow (top left) leaves the wall lamp floating. Cast shadows keep lamp anchored to the wall.
Drop shadow (top left) leaves the wall lamp floating. Cast shadows keep lamp anchored to the wall.

Lifewire / J. Bear

A drop shadow gives the illusion that the object is floating in front of or above the surface. The drop shadow on the light (upper left) doesn't help to anchor the light to the wall (visible or invisible).

With a cast shadow, the shadow stays attached to the base of the lamp while the rest of the shadow skews away from the lamp and onto the wall. The shadow makes the flat photo appear three-dimensional but not just floating in space. The upper right and two bottom images show just some of the possible cast shadows including solid and fading, hard and soft edges.

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Make Cast Shadows Part of the Background

Let the texture and color of the background show through cast shadows.
Let the texture and color of the background show through cast shadows.

Lifewire / J. Bear

Real shadows may darken the background but they don't cover it up. Use transparency to let the background colors and textures show through.

When the cast shadow strikes multiple surfaces, such as the ground and a wall, change the angle of the shadow to fit those varied surfaces. It may be necessary to create multiple cast shadows then use only the portion needed for each different surface it crosses.

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Match Cast Shadows With Form Shadows

Form shadows cover the side of the object away from the light.
Note how the side with the cast shadow is slightly darker, shadowed compared to the side toward the light source.

Lifewire / J. Bear

When an object casts a shadow, the side away from the light will also be in shadow. These form shadows are softer, often less defined than cast shadows. When taking a person or other object out of its original photograph to place in a layout, pay attention to the shadows and lighting on the figure. If the cast shadow you apply is inconsistent with the existing shadowing on the figure, you may need to apply brightness controls to select portions of the figure to recreate form shadows that match your new imaginary light source.

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