Staging pertains to how we arrange the image to communicate spatial information to the viewer. While composition deals more with aesthetics and ensuring that what information is there is readable, staging deals with the actual information itself.
Different techniques will give you access to different methods of staging. So as you flesh out your toolbox, you gain more ways to stage your image, although you don't need to use them all every time.
This post will look at some common combinations.
Flat Staging
With this type, everything is drawn flatly on a single plane parallel to the paper itself. This is how we naturally tend to stage images as children through the use of symbols. It's also commonly used in technical drawing, such as through orthographic blueprints or "flats."
The main information you can communicate in flat staging is the size of objects relative to one another, such as the height of one character compared to another. You can also communicate their position on that plane, such as one character standing on a crate to the left of another.
You can also do this with the ground plane, for example, such as showing the sizes and positions of race cars compared to one another on a winding track drawn like a map. The important part is that it's one plane, not the direction of the plane.
Parallax Staging
With this type, there are multiple parallel planes that overlap one another, but they aren't necessarily connected in space. This provides a rudimentary sense of depth and allows us to communicate basic information about what objects are closer or further than others.
You can incorporate effects based solely on the depth of a plane, like atmospheric perspective, but not other facets of perspective, as we aren't communicating things like distances and angles of diagonals in space. The gaps between flats or sides of forms aren't necessarily accurate or consisent to anything.
This is commonly used in children's storybooks, infographics, 2D games, and other simple stylized illustrations where neither invoking the "window into other world" feeling of perspective nor communicating 3D space bear any relevance.
This is also relevant to theatre work, where there are a ton of different points-of-view across the audience and not enough physical space to size everything in a scene relative to the foreground, so their priority is on communicating the illusion of depth rather than the illusion of perspective or accurate spatial mapping.
Parallel Staging
In this degree, images are drawn so that 3D space is accurately communicated, including the measurements of objects and angles and distances into the depth. The most common method of this is isometic drawing, but there are other methods as well, all known as parallel projections.
While these can communicate the plane the camera is on just by where they choose to cutoff the image, they don't communicate its exact position nor any other traits of the point-of-view, so they cannot be considered perspectives, despite common misnomers like "isometric perspective."
To.put it simply, you're drawing the scene from an angle, not from a point-of-view.
This method is commonly used to get a quick sense of a subject or design's 3D shape, and it's helpful to familiarize yourself with the forms like this before attempting a perspective drawing of a subject. It's also often seen in games where POV immersion is a lower priority than precisely communicating the 3D space.
When you're building 3D models that will be seen from many angles -- whether they are made digitally or as physical sculptures -- this is the main type of staging you are concerning yourself with, as it pertains to the objective 3D nature of the scene and objects.
Multi-Parallel Staging
This type of staging depicts a 3D scene by drawing different parts of it from different angles or scales. Different scales are typically used between foreground and background layers to simulate parallax staging in 3D, and different angles are used to describe the position of objects relative to the viewing angle to simulate perspective without vanishing lines.
This combination of simpler techniques can provide a rudimentary sense of camera position, but it has two notable downsides. Firstly, it won't be able to achieve any of the illusions that optical perspective can. And secondly, it only works on still images. If you try to pan the camera around, the effect becomes highly disorienting and overly complex to depict.
If you're just concerned with being able to show multple sides of structures and paths in a game setting, consider including a feature that rotates the entire stage / view in 45 or 90 degree intervals, rather than distorting the geometry along paths or splitting the view into pieces.
Perspective Staging
In this type of staging, everything is drawn relative to a point-of-view with a specific location and traits. Lines that aren't parallel to the image/paper converge towards points along the celestial sphere that correspond to particular angles of rotation. The location of these points changes depending on how the image is cropped and its focal length.
By matching up the POV of the viewer and the POV of the camera, you can create an optical illusion that makes the viewer feel like they are in the stage themselves or looking through a window into the stage. For that reason, this type of staging is most commonly used when immersion is the top priority.
Its ability to simulate a camera also makes it useful when drawing something that may be filmed or animated in the future, such as a comic, even though its panels are often too small to get a strong illusory effect.
Multi-Perspective Staging
This type of staging combines multiple perspectives in different areas of the image or across different objects. When poorly executed, it just looks like an amateur attempt at parallax or multi-parallel staging. And when well-done, it's sometimes hard to even tell there is more than one perspective.
The most common application of this is to show further into the distance than a single perspective would allow. The further objects are typically lifted to a higher ground plane and illustrated with a new POV. It's also commonly used to show around corners when multiple rooms or spaces are relevant to the scene.
Another common application of this is to spread an image across a large canvas, such as a ceiling or wall. By chaining together multiple perspectives, a single image can be extended to accommodate multiple viewers or a viewer moving across a distance over time.
While compositions that feature prominent mirrors can relate to this, the actual application is a bit different. A mirror serves as a contained frame for its own perspective. Whereas in multi-perspective staging, the geometry is actually connecting and distorting to merge these disparate view points.
Mixed Staging
Most complex works use some degree of mixed staging, where these different types are combined for different parts of the image. For example, in an image with otherwise accurate perspective, the leaves on a bush or the distant mountains might be stylized as symbols or textures and drawn in parallax.
This allows us to save some time and mental energy achieving the "effect of detail" without literally detailing everything to the same level of complexity. It can also give a more accurate impression of how our eyes and brain process a scene, as small or distant information is typically limited. (That's one of the notable differences between realism and hyperrealism.)
Besides this use, it's also common to employ these techniques along certain planes as you are drafting. For example, you might draw a box for a car, then draw the sides and front as flats on the surface of that box, then cut into the box and connect them.
You need to understand the flats to apply them to the forms, and you need to understand the forms to distort them with the camera. So you work your way up through these, learning to communicate spatial information more accurately at the outset of an image, then work your way back down them, applying identifying details upon the space you've established in each image.
How does staging differ from approach?
Approach can be thought of as patterns of skills artists tend to apply together according to common needs, to depict their subjects and scenes. Staging is just one category of skill an approach considers.
So a constructive artist is likely to use parallel or perspective staging, but there's also nothing stopping them from treating a constructed drawing of a tree like a parallax layer without any depth to its forms.
You're not locked into one type of staging just because of your preferred approach. Even a 2D symbol could be staged in perspective, like word art drawn to a vanishing point. But some forms of staging are more logically associated with certain approaches.