# Coordinates, field and markers

The whole scene is tracked by a camera in order to provide a localization for the robots and the ball. We use visual codes named ArUco as fiducial markers to detect the corner of the fields and the robots.

The ball is detected using its color (orange).

## Field dimensions

Here are the main field dimensions:

If you want to deploy the kit, we recommend a floor footprint of about 2.5m x 2.5m. Indeed, you need some extra space around the field to deploy the structure for hold the camera.

## Coordinates system

The field coordinates used in the software are the following:

• The frame’s origin is the middle of the field, and robots orientation are angle formed by field x axis and front of the robot.
• We use international system units, distances are then expressed in meters and orientations in radians.
Roughly, the coordinates of the blue robot above will look like (x=0.4 m, y=0.4 m, alpha=pi/4 rad).

## Robots

You can print green and blue markers and place them on the robots:

## Markers

Markers are ArUco 4x4, you can use tool like this one, printed with a scale of of 8 cm for the robots and 16cm for field corners. The PDF provided previously are 1:1 scale. The ArUco ids are:

• 0: field corner 1
• 1: field corner 2
• 2: field corner 3
• 3: field corner 4
• 4: robot green 1
• 5: robot green 2
• 6: robot blue 1
• 7: robot blue 2
• 8-15: generic objects