There are five levels of illumination namely Bright, Normal, Dim, Dark and Supernatural Dark. An area will have an ambient level of light as is dependant on its environment such as in an open field during the day, under a canopy of trees, or in a dungeon.
These levels can be influenced through the use of artificial, magical and natural sources of light. An artificial light source are such items as candles, lanterns, sun-rods and torches. Some mosses and molds can also have the ability to raise the level of illumination within an area. These are also classed as artificial light sources. Magical sources of light come from spells such as Darkness, Deeper Darkness, Light and Daylight. There is only one form of natural light and that is light cast by the sun. This light source can never be countered but can be affected through reduction of its illumination level such as through the use of spells. Table 7–10 of the Core Rule Book provides effects that the various types of light sources have including their immediate and secondary areas and how long each item lasts. Note that secondary levels of illumination stack up to a maximum of normal illumination.
Bright Illumination include areas which are outside in direct sunshine and inside the area of a daylight spell. In an area of bright illumination, all characters can see clearly. Some creatures, such as those with light sensitivity and light blindness, take penalties while in areas of bright illumination. A creature can’t use Stealth in an area of bright illumination unless it is invisible or has cover.
Normal Illumination functions just like Bright Illumination, but characters with light sensitivity and light blindness do not take penalties. Areas of Normal Illumination include underneath a forest canopy during the day, or in an open field either on sunrise or sunset, or in the shadow of an alley.
In an area of Dim Illumination, a character can see somewhat. Creatures within this area have concealment (20% miss chance in combat) from those without darkvision or without the ability to see in darkness. A creature within an area of Dim Illumination can make a Stealth check to conceal itself against creatures lacking darkvision or the ability to see in darkness. Areas of Dim Illumination include outside at night with a visible moon in the sky or bright starlight.
In an area with a *Dark Illumination* level, creatures without darkvision are effectively blinded and suffer from the blinded condition while within an area of darkness (p565 of the Core Rule Book). Areas with a dark Illumination level include an unlit dungeon chamber, most caverns, and outside on a cloudy, moonless night.
In an area with a Supernatural Dark Illumination level, all creatures, including those with darkvision, are effectively blinded as per the Dark Illumination level. Supernatural Darkness can only be achieved through the use of magic such as Deeper Darkness.
Characters with low-light vision (i.e. elves, gnomes, and half-elves) can see objects twice as far away as the given radius of the illumination they are in. Double the effective radius of Bright Illumination, Normal Illumination, and Dim Illumination for such characters. In the case where a character with low-light vision is in an area open to the elements where there is moon light, they may see without penalty.
A spellcaster can read a scroll or read from a spell book as long as he is in an area which has a Normal Illumination level or greater. Characters with darkvision (i.e. dwarves and half-orcs) can see normally in areas with a Dim or Dark level of Illumination within 60 feet. A creature can’t hide within 60 feet of a character with darkvision unless it is invisible or has cover.