Introduction and Background

You might be wondering, “Wait—what kind of problem is this? What does it have to do with science?”

Here is what happened. About a year earlier, I had just bought Pokémon Scarlet and Violet. I streamed myself playing while casually poking fun at the occasional little bug and graphical glitch.

To be fair, those little bugs were minor. They did not really hurt the overall experience.

Before getting to the physics, I should briefly introduce the setting of Pokémon Scarlet and Violet so the rest of the article makes more sense.

Pokémon Scarlet and Violet are set in a region called Paldea.

Paldea is a fictional region with many natural environments, including lakes, grasslands, and snowy areas. One of its most distinctive features is the enormous hole in the middle of the map known as the Great Crater of Paldea [1] .

What is actually inside the Great Crater is… wait, that would spoil too much. Let us keep it simple: the crater contains a surprisingly rich environment and ecosystem, and one area is filled with large, mirror-like crystals.

While I was happily absorbed in the world and story of Pokémon Scarlet and Violet and wandering around the map, I suddenly saw an image that completely pulled me out of the game.

A game screenshot of my character reflected by one of the giant crystals in the Great Crater of Paldea.
A game screenshot of my character reflected by one of the giant crystals in the Great Crater of Paldea.

That reflection is completely inconsistent with ordinary geometrical optics. The high-school physics teacher inside me immediately caught fire, and somehow I became very serious while playing a video game.

And that is how this article was born.

The Great Crater Crystals and Plane-Mirror Imaging [2]

Analyzing the Imaging Behavior of the Great Crater Crystals

Let us set aside the chemical nature of the crystals in the Great Crater—and also set aside the possibility that the whole thing is simply magic.

These crystals appear to have flat, smooth surfaces. When the character stands in front of one, the image looks almost identical to the character and does not show obvious distortion.

So, for the purpose of this analysis, we can treat these crystals as having mirror-like optical behavior.

That means the image formed when the character stands in front of the crystals can be analyzed using the basic principles of plane-mirror imaging.

Basic Terms for Plane-Mirror Imaging

Before discussing the properties of plane-mirror images, we need a few basic terms related to image formation.

These terms also apply more broadly to images formed by mirrors and lenses, not only plane mirrors.

Basic image-formation terminology, illustrated by the author for reference with the definitions below.
Basic image-formation terminology, illustrated by the author for reference with the definitions below.

Object: something that either emits light or reflects light.

Image: an optical image formed after light emitted or reflected by an object is reflected by a mirror or refracted by a lens. If the rays actually converge, the result is a real image; if only their backward extensions appear to originate from a location, the result is a virtual image. [6]

Object distance: the distance between the object and the mirror.

Image distance: the distance between the image and the mirror.

Why Can We See Ourselves in the Crystal?

The Great Crater is extremely deep, but some light still reaches the bottom—at least according to the game—and equipment in the crater also provides illumination. Humans do not emit visible light on their own, but we do reflect the ambient light around us.

So the player character standing in front of the crystals should be treated as an object reflecting ambient light, not as a self-luminous light source. [5]

When light reflected from us reaches surrounding materials, several things can happen, including reflection, refraction, and absorption of light energy.

Illustration by the author showing reflection and refraction when light reaches a boundary between media.
Illustration by the author showing reflection and refraction when light reaches a boundary between media.

Suppose we call the original environment of the light medium 1 and the material it encounters medium 2. The boundary between them is the interface.

Part of the incident light can be reflected at the interface and return to the original medium. This is reflection.

Another part of the light can enter the second medium. That transmitted ray is refracted, and the phenomenon is called refraction.

The character can see an image because ambient light reflects from the character, reaches the mirror-like crystal surface, and is reflected again into the observer’s eyes.

In other words, the reason we can see ourselves in front of the crystal is fundamentally the reflection of light from that large reflective surface.

Reflection, the Law of Reflection, and Types of Reflection

Since seeing ourselves in the crystal depends on reflection, let me spend a little more time on how reflection works before moving on.

At the point where a ray strikes the interface, draw a line perpendicular to the surface. This is the normal—the dashed line in the previous figure. Reflection follows the law of reflection: the angle of incidence, measured between the incident ray and the normal, equals the angle of reflection, measured between the reflected ray and the normal.

If a bundle of parallel rays strikes a smooth mirror surface, the surface normals are aligned, so the reflected rays remain parallel. This is specular reflection [3][5] .

Specular reflection with parallel reflected rays, illustrated by the author.
Specular reflection with parallel reflected rays, illustrated by the author.

Not every surface is as smooth as the crystal. On a rough surface, each ray still obeys the law of reflection locally, but the surface normals point in different directions, so the reflected rays spread out. This is diffuse reflection [4] .

Diffuse reflection with non-parallel reflected rays, illustrated by the author. Note that this simplified diagram is not drawn as a precise ray construction from the law of reflection.
Diffuse reflection with non-parallel reflected rays, illustrated by the author. Note that this simplified diagram is not drawn as a precise ray construction from the law of reflection.

Properties of Plane-Mirror Images

We have argued that the character can see an image in the giant crystal because of mirror-like reflection. So next, let us look at some important properties of images formed by a plane mirror.

Plane-mirror imaging follows the law of reflection. To locate the image, we can draw any two rays from the same point on an object and trace how they reflect from the mirror.

Ray diagram showing two rays from the same object point reflecting from a mirror.
Ray diagram showing two rays from the same object point reflecting from a mirror.

The incident and reflected rays must, of course, satisfy the law of reflection: the angle of incidence equals the angle of reflection.

If we extend the two reflected rays backward behind the mirror, their extensions intersect at a point. That point locates the image formed by the plane mirror.

The image location found by extending the reflected rays backward, illustrated by the author.
The image location found by extending the reflected rays backward, illustrated by the author.

From the geometry, the perpendicular distance from the object to the mirror equals the perpendicular distance from the image to the mirror. In other words, object distance equals image distance, and the image has the same size and shape as the object.

If you stand in front of a mirror and raise your right hand, the image seems to raise its left hand. High-school physics often describes this as “left-right reversal.” More precisely, however, a plane mirror reverses the direction perpendicular to the mirror—the front-back axis. “Left-right reversal” is the intuitive description we get from comparing ourselves with the image while facing it. [7]

In the mirror, the woman appears to support her cheek with her right hand, while the actual woman in front of the mirror is using her left hand—an everyday example of the familiar mirror-reversal effect.
In the mirror, the woman appears to support her cheek with her right hand, while the actual woman in front of the mirror is using her left hand—an everyday example of the familiar mirror-reversal effect.

So What Is Wrong with the Reflection?

We have spent quite a bit of time on reflection and the properties of plane-mirror images.

Using the way the character appears in front of the crystal, we have treated the crystal as a mirror-like surface whose image should follow ordinary reflection and plane-mirror imaging.

Now we can finally return to the original question: what exactly is wrong with that first screenshot of my character standing in front of the crystal?

I simplified the character into a basic diagram below. Because the character is standing with their back to the mirror and a human body has thickness, the back of the head is closer to the mirror while the face is farther away.

Diagram by the author showing the separate image positions of the back of the head and the face when the character stands in front of the crystal.
Diagram by the author showing the separate image positions of the back of the head and the face when the character stands in front of the crystal.

From the diagram, the reason becomes clear. Because object distance equals image distance, the image of the back of the head should lie closer to the mirror, while the image corresponding to the face should lie farther behind it.

Those parts overlap along the viewing direction, so the face should not suddenly become visible. A third observer looking at this setup should primarily see the back of the character’s head in the mirror.

So if the giant crystal really behaves like an ordinary plane mirror, the scene should look more like the version below.

An edited game image showing the reflection the character should form under the plane-mirror model used in this article.
An edited game image showing the reflection the character should form under the plane-mirror model used in this article.

There is another issue as well: a plane-mirror image should be the same size as the object. The original game image does not match the character’s apparent size, so I also adjusted the image scale slightly when editing the screenshot.

The edited result looks much more consistent with ordinary plane-mirror imaging—and that is why the original scene felt so wrong to me when I first saw it in Pokémon Scarlet and Violet.

Conclusion

This article began with a scene from Pokémon Scarlet and Violet and used the visible behavior of the crystal to model it, for the purpose of analysis, as a mirror-like surface.

We then used the law of reflection and the properties of plane-mirror images to explain why the character’s reflection is inconsistent with that model, and used an edited screenshot to show a version that better matches the physics.

Of course, the entire analysis rests on one very important assumption: that this part of the Pokémon world follows physics close enough to the real world for ordinary geometrical optics to apply, rather than operating by pure magic.

If it really is a magical world, then plenty of real-world scientific rules may not apply—and this whole analysis would need to be reconsidered. That caveat matters!

I hope slipping a little serious science into a lighthearted game gives you a useful intuition for light, reflection, and the basic properties of plane-mirror images.

References

[1] Pokémon Scarlet and Violet - Wikipedia (Chinese), URL：https://zh.wikipedia.org/wiki/%E5%AF%B6%E5%8F%AF%E5%A4%A2_%E6%9C%B1%EF%BC%8F%E7%B4%AB

[2] Walker, J., Halliday, D., & Resnick, R. (2011). Fundamentals of physics. Hoboken, NJ: Wiley.

[3] Specular Reflection - Wikipedia (Chinese), URL：https://zh.wikipedia.org/wiki/%E9%8F%A1%E9%9D%A2%E5%8F%8D%E5%B0%84

[4] Diffuse Reflection - Wikipedia (Chinese), URL：https://zh.wikipedia.org/wiki/%E6%BC%AB%E5%8F%8D%E5%B0%84

[5] The Law of Reflection - College Physics 2e, OpenStax，URL：https://openstax.org/books/college-physics-2e/pages/25-2-the-law-of-reflection

[6] Image Formation by Mirrors - College Physics, OpenStax，URL：https://openstax.org/books/college-physics/pages/25-7-image-formation-by-mirrors

[7] Image Characteristics of Plane Mirrors - The Physics Classroom，URL：https://www.physicsclassroom.com/Class/refln/u13l2b.cfm