Overpass API Extension

The OverpassAPI extension adds toggle buttons to the map for fetching and displaying OpenStreetMap features (roads, buildings, parks, etc.) via the Overpass API.

Setup

The extension activates automatically when both GeoExplorer and OverpassAPI are loaded:

using Pkg
Pkg.add(url="https://github.com/RallypointOne/OverpassAPI.jl")

using GeoExplorer, OverpassAPI

Quick Start

using GeoExplorer, OverpassAPI, Extents

# Launch map centered on Boulder, CO
app = explore(extent=Extents.Extent(X=(-105.30, -105.25), Y=(40.00, 40.03)))

# Add Overpass controls with default features
add_overpass_controls!(app)

This adds a panel of toggle buttons in the bottom-left corner of the map. Click a button to fetch and display that feature type for the visible map extent. Click again to hide it. Use Refresh to re-fetch active features after panning or zooming.

using GeoExplorer, OverpassAPI, GLMakie, Extents

fig = Figure(size=(800, 600))
app = explore(extent=Extents.Extent(X=(-105.285, -105.26), Y=(40.005, 40.025)), figure=fig)
controls = add_overpass_controls!(app)

# Programmatically activate Roads, Buildings, and Parks
for name in ["Roads", "Buildings", "Parks"]
    controls.buttons[name].clicks[] = 1
end

wait(app.map)
save("overpass_controls.png", fig)

Overpass controls showing roads, buildings, and parks in Boulder, CO

Default Features

Button	Query	Plot Style
Roads	OQL.way["highway"]	Gray lines
Buildings	OQL.way["building"]	Orange polygons
Water	OQL.way["natural" => "water"]	Blue polygons
Parks	OQL.way["leisure" => "park"]	Green polygons
Amenities	OQL.node["amenity"]	Red scatter

Custom Features

Use OverpassFeature to define your own feature buttons:

using GeoExplorer, OverpassAPI, Extents
using OverpassAPI: OQL

app = explore(extent=Extents.Extent(X=(-105.30, -105.25), Y=(40.00, 40.03)))

add_overpass_controls!(app, features=[
    OverpassFeature("Roads",       OQL.way["highway"],                    :gray50,     :lines),
    OverpassFeature("Buildings",   OQL.way["building"],                   :orange,     :poly),
    OverpassFeature("Restaurants", OQL.node["amenity" => "restaurant"],   :red,        :scatter),
    OverpassFeature("Schools",     OQL.node["amenity" => "school"],       :purple,     :scatter),
])

OverpassFeature Fields

Field	Type	Description
name	String	Label for the toggle button
query	Any	An OQL query expression
color	Any	Any valid Makie color
plot_type	Symbol	:lines, :poly, or :scatter

Keyword Constructor

# Positional
OverpassFeature("Roads", OQL.way["highway"], :gray, :lines)

# Keyword (color and plot_type have defaults)
OverpassFeature("Roads", OQL.way["highway"]; color=:gray, plot_type=:lines)

Tips

• Zoom in before fetching — large extents can return a lot of data and slow down the Overpass API.
• Use Refresh after panning/zooming to update active layers for the new view.
• The :poly plot type works best for closed ways (buildings, parks, water bodies). Use :lines for open ways (roads, paths).