Plot Layout

This demo demonstrates visualizing electrode layout configurations in 2D and 3D space.

What is Electrode Layout?

Electrode layout defines the spatial positions of EEG sensors on the scalp using:

• 2D coordinates (x, y): Projected positions for topographic maps

• 3D coordinates (x, y, z): Actual positions on spherical head model

• Spherical coordinates (incidence, azimuth): Angular positions

Layout Visualization Functions

plot_layout_2d:

• Standard topographic view from above

• Shows electrode positions and labels

• Customizable head outline, markers, and labels

• Supports region-of-interest highlighting

plot_layout_3d:

• Full 3D spherical visualization

• Interactive rotation and zoom

• Shows true spatial arrangement

Neighbor visualization:

• Display spatial relationships between electrodes

• Helps verify interpolation neighborhoods

• Interactive hover to show connections

Use Cases

Verify electrode montage:

• Confirm correct channel positions

• Check for mislabeled electrodes

• Validate custom layouts

Publication figures:

• Document electrode positions

• Highlight regions of interest

• Create publication-ready diagrams

Analysis planning:

• Understand spatial sampling density

• Plan interpolation strategies

• Define ROIs for analysis

Customization Options

Head outline:

• Color, line width, radius

Electrode markers:

• Marker style, size, color

• Show/hide markers

Labels:

• Font size, color

• Position offsets

• Show/hide labels

Regions of interest (ROIs):

• Highlight electrode groups

• Customizable borders and fills

• Multiple ROIs with different styles

Neighbor Detection

Calculate spatial neighbors based on distance thresholds:

• 2D neighbors: Using projected coordinates

• 3D neighbors: Using spherical coordinates

• Export neighbor definitions for channel repair

Workflow Summary

This demo shows electrode layout visualization:

Basic 2D Visualization

• Load electrode layout

• Convert to 2D coordinates

• Plot with default settings

Customize Appearance

• Adjust head outline (color, width, radius)

• Modify markers (style, size, color)

• Customize labels (size, color, offsets)

Add Regions of Interest

• Highlight electrode groups

• Customize ROI borders and fills

• Create multiple ROIs with different styles

Neighbor Visualization

• Calculate neighbor relationships

• Plot with neighbor connections

• Export neighbor definitions

Save Figures

• Export publication-ready figures

• Use CairoMakie for vector graphics

Code Examples

Show Code

# Demo: Layout Visualization
# Shows electrode layout plotting and manipulation.

using EegFun
# Note: EegFun.example_path() resolves bundled example data paths.
# When using your own data, simply pass the file path directly, e.g.:
# dat = EegFun.read_raw_data("/path/to/your/data.bdf")

const DEMO_OUTPUT = "./demos/output/"
mkpath(DEMO_OUTPUT)

layout = EegFun.read_layout(EegFun.example_path("layouts/biosemi/biosemi72.csv"));
EegFun.polar_to_cartesian_xy!(layout, preserve_radial_distance = true);

# basic plot
EegFun.plot_layout_2d(layout)

# some customisations
EegFun.plot_layout_2d(layout; head_color = :grey, head_linewidth = 5, head_radius = 1.5)
EegFun.plot_layout_2d(layout; point_plot = false, label_plot = false)
EegFun.plot_layout_2d(layout; point_marker = :x, point_markersize = 20)
EegFun.plot_layout_2d(layout; point_color = :red)

EegFun.plot_layout_2d(layout; label_fontsize = 20, label_color = :grey)

# Annotating plots with ROIs
result = EegFun.plot_layout_2d(layout)
EegFun.add_topo_rois!(result.axes[1], layout, [[:PO7, :PO3, :P1], [:PO8, :PO4, :P2]], roi_border_size = 0.05)
EegFun.add_topo_rois!(result.axes[1], layout, [[:PO7, :PO3, :P1], [:PO8, :PO4, :P2]], roi_border_size = 0.1)
EegFun.add_topo_rois!(
    result.axes[1],
    layout,
    [[:Fp1]],
    roi_border_size = 0.10,
    roi_fill = [true],
    roi_linecolor = [:black],
    roi_fillcolor = [:red],
    roi_fillalpha = [0.2],
)
EegFun.add_topo_rois!(
    result.axes[1],
    layout,
    [[:CPz, :C2, :FCz, :C1]],
    roi_border_size = 0.15,
    roi_linewidth = [5],
    roi_fill = [true],
    roi_linecolor = [:blue],
    roi_fillcolor = [:green],
    roi_fillalpha = [0.5],
)

# Plots with neighbours (hover mouse over channel to show neighbour connections)
EegFun.get_neighbours_xy!(layout, 0.5);
EegFun.plot_layout_2d(layout, neighbours = true)

# Print neighbours while 2D neighbours are still computed
# (the 3D coordinate conversion below clears cached neighbours)
EegFun.print_layout_neighbours(layout, joinpath(DEMO_OUTPUT, "electrode_neighbours_1.toml"))
EegFun.print_layout_neighbours(layout.neighbours, joinpath(DEMO_OUTPUT, "electrode_neighbours_2.toml"))

# 3D layout with neighbours
EegFun.get_neighbours_xyz!(layout, 0.5);
EegFun.plot_layout_3d(layout, neighbours = true)

# save a basic figure
# NB. for vector graphics, use CairoMakie
# save("topo_roi.png", result.fig)

See Also

• API Reference