Types of Vision

In the world of ReD&D, there are many ways of perceiving the world around oneself. Because we are all humans (presumably), the game is based on human standards, and then expanded from there. This means there are quite a bit of interesting permutations of "sight," including some that aren't really sight at all.

Types of Vision
There are several different types of vision. In this case, vision refers specifically to the ability to see, in some form or another. It is worth noting that whenever "normal vision" is written, it means what is normal for a human with 20/20 vision.

Darkvision
Darkvision is a type of supernatural sight. While not as powerful as truesight, darkvision allows a creature to see in darkness, even magical darkness, because they are seeing minute auras and subtle overlays of energies, not truly using light or heat to see.

Darkvision acts just like normal sight, except it is completely in black and white (or some other monochromatic color scheme; some see in green and yellow, blue and orange, or even strange combinations). Otherwise, details can be seen just as normal. Even though darkvision relies on supernatural means to see, it does not grant any special ability to recognize magical or supernatural effects.

Darkvision is notoriously difficult to deceive, because it sees through normal means of restricting vision, namely lack of light, bursts of light, hot and cold walls, and the like. Illusions act as normal to darkvision, and thus are still effective, but most other things can be seen through.

Low-Light Vision
Low-light vision is a trait some creatures possess, which allows them to see just as well at night as during the day. This means that, whereas humans receive penalties for fighting in conditions of low light, such as in moonlight, in torchlight, or in an area where light is simply reduced, but still existent, creatures with low-light vision do not face any penalties.

Improved Low-Light Vision
Some creatures are actually better at seeing in areas of low light than in normal sunlight. This does not mean that these creatures take penalties in normal light, simply that when in conditions of low light, they can see farther. Specifically, improved low-light vision allows a creature to see twice as far in low light conditions than they can in full sunlight.

Superior Low-Light Vision
Even better than improved low-light vision, superior low-light vision is a trait possessed by very few creatures. These creatures usually operate almost entirely at night, or in similar times or areas of lessened light. These creatures can see three times as far in conditions of low light as they can in normal sunlight.

While it is theoretically possible to have creatures who can see even further than this in areas of low light, it seems redundant to have creatures possess anything more than superior low-light vision. If you really want them to possess better night vision, then it is suggested you just give them it.

Truesight
The ultimate in vision, truesight is actually type of supernatural knowing. Rather than see things, truesight allows a creature to perceive the very fabric of the multiverse itself, thus seeing through darkness, illusions, and even mundane disguises. While extremely rare, truesight is an extremely powerful and sought after ability. Almost no creatures innately possess truesight, requiring some artificial means of acquiring it.

Truesight sees through illusions, invisibility, but also more innate things such as incorporeality and etherealness.

Undervision
Also know as infrared vision, undervision is a type of sight that relies on heat signatures to recognize the surroundings. This type of vision is different than normal vision, in a number of ways. First, it is not as detailed. While depth can be perceived, more specific features, such as texture, color or variations in materials cannot be perceived, unless they are a different temperature than another material.

Creatures with undervision can see in areas of complete darkness, because they do not rely on visible light; they rely on heat. It is worth noting, some supernatural abilities can alter the temperature of things, so it is still perfectly possible to confound creatures with undervision as it is with creatures who possess normal vision.

Additionally, many creatures with undervision lack the ability to see with normal vision. Those who possess undervision as an artificial trait, such as through magic, usually have to switch between undervision and normal vision. There are some creatures who simply possess both, however, and can see in both at once.

While it is not always the case, many creatures with undervision possess some form of light blindness, where bright flashes of visible light can blind them. If they possess it, it is noted in their entries.

Other Forms of Perception
While sight is a very common feature for creatures to possess, it is not the only type of perception. Many creatures possess other, sometimes more subtle, ways of viewing the world. These are discussed below.

Blindsense
Blindsense is a special type of perception, utilizing vibrations in the air, echolocation, or other tools to recognize where creatures and objects are in relation to oneself. This does not reveal such things as texture, color, or subtle details, but more just whether an object is taking up space, and where such an object is, and perhaps rudimentary shapes of said objects.

Scent
Some creatures possess such a powerful sense of smell that they can track using it, detect changes in emotions, and other subtle notions. Creatures with the scent perceptive quality are among those creatures. Scent is mostly useful in determining general directions and more subtle things, such as emotions, than they are with detecting things such as how a creature is moving or if it is getting ready to attack.

Tremorsense
Tremorsense is a type of perception common to burrowing creatures and those which possess and innate connection with the earth. While most creatures possess an extremely diluted tremorsense-like ability, allowing them to feel the ground shaking and the like, a creature which truly possess tremorsense can actively recognize where creatures touching the earth are, if they are moving, how they are moving, and even subtler notions, such as how heavy they are and how much of their body actually touches the ground. It can't reveal much more beyond that (such as if they are swinging a weapon or getting ready to fire a gun), but it is still very useful.