Vision



Vision describes what a unit can and cannot see within a circular area from its current location and state. Places a unit cannot see are filled with the Fog of War, a dark mist that hides enemy units inside of it. Allied units cannot be hidden by the fog of war. Invisible units cannot be seen even when outside of the Fog of War, unless they are revealed by a source of True Sight. Trees and higher elevation block a unit's vision if it has ground vision. Flying vision is unobstructed by trees and elevation. Abilities can grant vision over areas as well, usually for a short amount of time and limited to their area of effect.

All vision is shared within a team, which means that everything allied units see can be seen by the player as well. This includes allied player-controlled units, as well as NPC units, like lane creeps and buildings.

Fog of War
All areas outside of friendly vision are constantly covered by the Fog of War. Any non-friendly units within the Fog of War cannot be seen or directly targeted, however they can still be hit by non-targeted spells. To unveil units in the Fog of War, an allied unit must gain vision over that area.

If an enemy enters the fog of war during the cast time of an ability, the cast gets canceled. However, attacks do not cancel if their targets enter the fog of war during the attack animation.

Elevation
The Dota 2 map's cliffs and valleys shape the battle, determining both where units can move and what they can see. Units with ground vision cannot see areas that are on higher elevation than them. For example, a unit standing in the river (which is the on the lowest elevation) cannot see anything past the cliffs surrounding the river, or beyond the ramps leading out of the river.

On the other side, units standing on higher elevation effectively have unobstructed vision on lower elevation. For example, a unit standing on an elevated ward spot can see the entire surrounding, unobstructed by nearby trees, regardless of their vision type.

Units with flying vision do not have their vision obstructed by higher elevations.

Trees
Besides blocking pathing, trees also block vision for units on the same elevation as them, and for units one elevation above them. Trees block vision like how objects cast shadows: The closer the object is to the source of light, the bigger and wider the object's shadow gets. The closer a unit is to a tree, the more vision is blocked by the tree, blocking out an entire section of the circular vision area of the unit. The exact numbers for these are unknown.

The small trees created by, , , and have a narrower vision blocker than the regular trees on the map.

Units with flying vision do not have their vision obstructed by trees.

Vision blockers
Besides trees and higher elevation, there are also some artificial vision blockers. 's pit entrance is sealed by a vision blocker, preventing units from outside the pit from seeing inside it, and units from inside to see outside of the pit. Both fountains have a vision blocker at their stairs as well, preventing enemies of the respective teams from seeing inside the fountain area. However, this vision blocker is redundant, since the fountains' higher elevation creates the same effect.

Currently, no ability creates artificial vision blockers.

Units with flying vision do not have their vision obstructed by vision blockers.

Time of day
Another factor in vision range is the current time of day. Most units' vision range is lower during nights and higher during the day, although there are exceptions to this, with some units having lower vision during the day and higher at night, and some units having the same vision regardless of daytime.

Base vision ranges
Most units have day and night vision, only very few have absolutely no vision. These values can be altered with vision bonuses and reductions.

Heroes
All heroes have a vision range of 1800 during the day and 800 during the night, except for following

Creeps
All lane and jungle creeps have a vision range of 800 during the day and the night, except for following

Summons
All summons creeps have a vision range of 800 during the day and the night, except for following

Types of Vision
There are 2 types of vision, ground vision (also known as obstructed vision) and flying vision (also known as unobstructed vision). Ground vision is impaired by higher elevations, trees, and vision blockers, while flying vision is completely unhindered.

Every hero has ground vision. Other units have the following vision types

Modifying vision
Several abilites and items have abilities that grant or reduce vision.

Vision setting abilities
These abilities set a unit's vision to a specific value.

Sources of vision
Units are not the only entities with vision. A lot of abilities are able to create vision cells of varying sizes on the world, revealing an area of a fixed duration.

Caster vision
Caster vision is a vision cell granted to the victims of targeted spells and attacks. Whenever a unit casts a spell (except ) on an enemy within 1800 range, or performs an attack on them, the enemy gains 150 radius ground vision around the casting or attacking unit which lasts for 2 seconds. This vision prevents players from easily and constantly harassing enemies from the fog of war, especially with long-distant spells that can be spammed easily like, or with ranged attacks.

Only one of these vision cell can exist per unit. This means if a vision cell already exists from a previous targeted order, performing another targeted order within the previous vision cell's duration does not create a second vision cell. Instead, the location of the previous vision cell gets updated, its duration gets reset, and its vision type is changed to flying vision.

Caster vision is also applied upon launching an attack. The result of the attack does not matter, if the attack is executed, the vision is granted.

Ground vision
Ground vision is obstructed by trees, higher elevations, and vision blockers.

Flying vision
Flying vision is not obstructed by trees, higher elevations, and vision blockers.

Shared Vision
Some abilities are capable of sharing an enemy unit's vision the player's team. This means anything that unit sees can also be seen by its opponents.

Exposing
Several abilities are capable of exposing an enemy's model through the fog of war, without truly providing vision over them. This means their surroundings are still shrouded by the fog, but they are visible and targetable as if they were not within the fog of war. Exposed enemies are treated as visible units by every spell.

Exposing an enemy does not cancel out the effects of invisibility, although it does make their silhouette visible. An exposed invisible enemy has its location revealed, and can even be selected like a visible enemy, but is still almost fully treated as an invisible unit. This means it still cannot be targeted by attacks or single-targeted abilities, and still counts as invisible in terms of abilities affecting them, with a very few exceptions. Some sources of exposure also provide True Sight to fully reveal the enemy, but not all do.

Exposing is a default component of shared vision, so that all spell listed in the previous section expose enemies as well. Besides them, the following abilities expose enemies.

Vision interaction with spells
Generally, unit-targeted spells require vision over the target, while ground targeted or non-target spells may be cast regardless of vision. Once cast, a spell usually works regardless of vision. Area effects usually do not require vision to affect enemies. Some non-targeted spells that do the targeting themselves may require vision over enemies. There are exceptions to all of these.

The following spells require vision over enemies to affect them

1Requires.

2Requires a talent.

3When the current target of these spells die, they choose new targets. Only choose visible enemies.

4 ends immediately if the target enters the fog of war.

5When Starstorm's initial wave requires vision over enemies, the secondary single projectile does not.

6When items and  only target visible secondary targets.

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