Skip to content

Latest commit

 

History

History
50 lines (34 loc) · 3.32 KB

observations.md

File metadata and controls

50 lines (34 loc) · 3.32 KB
Raw

Agent Observations

This page details the observations available to the agent.

The agent currently has access to a Camera, Raycasts, and Extra Observations. You can disable either the camera or raycasts (or both). The enabled observations are ordered in an array with Camera first (if enabled), then raycasts (if enabled), then the extra observations.

Camera Observations

With the camera enabled (via useCamera) the agent receives 1st-person pixel observations of its environment with configurable (square) resolution (via resolution parameter). Grayscale can be toggled on/off.

Raycast observations

Raycasts are implemented to make it easier to work with a wide range of algorithms within AnimalAI. They are not designed to compete with pixel inputs as they naturally contain much less information about the environment. Nevertheless, they can be extremely useful for prototyping and for testing certain cognitive abilities or when analysing network dynamics compared to performance on many tasks. They can also be used as an auxilliary input or to help learn a more symbolic-like representation of the environment.

There are four relevant arguments to pass to the environment when using raycasts. See the lowLevelAPI.py script for examples.

  • useCamera: set to false if you do not also want pixel observations
  • useRayCasts: set to true to use raycast observations
  • raysPerSide: sets the number of rays to cast to the left and right of the central one. e.g raysPerSide=2 means 5 rays total
  • rayMaxDegrees: sets the maximum degrees for the left/right rays. e.g. 90 means the agent casts rays exactly to the left and right. other rays are spaced equally between the center and the max.

There are currently 6 types of objects that the rays report. This is intentional to keep the observation space down, but does limit the types of problem solvable. In order they are:

  • arena: this is the outside of the arena and should usually be hit by a ray if it misses other objects (this is useful for the distance)
  • Immovable: Inner Walls, Cylinders, ramps i.e. all the objects listed under immovable here
  • Movable: Cardboxes and L/U objects i.e. all the objects listed as movable here
  • goodGoal: A green goal
  • goodGoalMulti: A yellow goal
  • badGoal: Both red goals and death zones.

Note that this means that ramps and transparent objects are not distinguished from opaque walls, thus limiting the number of tasks it is possible for a raycast only agent to solve. This set may be extended in future versions.

For each ray:

  • The first 6 elements of the returned observation are a one-hot vector for the type of object hit (ordered as above).
  • The next element is 0 if the ray hit something (1 otherwise).
  • The next element is the normalised distance to the object that was hit.

So the full observation space is of size 8 * (2*raysPerSide + 1)

Note that Unity implementation of rays orders the central ray first and then each ray (left or negative offset first) in increasing distance from the centre as follows:

  1 0 2
   \|/
3 --@-- 4

AnimalAI contains a helper class as a starting point for manipulating raycasts.

Health, Velocity and Position

The agent also receives a vector of length 7 containing its health (1 float), velocity (x, y, z), and (global) position (x, y, z).