# Figure-ground diagrams

    library(osmnxr)

A figure-ground diagram draws a city’s streets in one colour on a solid background, with no labels or axes. Cropping different places to the same extent makes their network form directly comparable — one of the most recognisable OSMnx visuals (Boeing 2025, Figure 3).

## A single diagram

`ox_plot_figure_ground()` renders any `osm_graph`. Here is the bundled real network of central Olinda, Brazil (loaded offline):

    g <- ox_example("olinda")
    ox_plot_figure_ground(g)

## Comparing network form

The package bundles three real networks that span the morphological spectrum: a rigid grid (Midtown Manhattan), an irregular colonial core (Olinda), and an ancient organic city (Rome). Side by side, their differences are immediate:

    op <- par(mfrow = c(1, 3))
    ox_plot_figure_ground(ox_example("manhattan"), title = "Manhattan")
    ox_plot_figure_ground(ox_example("olinda"),    title = "Olinda")
    ox_plot_figure_ground(ox_example("rome"),      title = "Rome")

    par(op)

This is the visual counterpart to street-orientation entropy (see the Street orientation article): Manhattan’s grid reads as a few crisp directions, while Rome’s tangle points everywhere.

## Your own places

With network access, build a figure-ground for any place. Cropping each to the same buffer distance keeps the comparison fair:

    places <- c("Barcelona, Spain", "Tunis, Tunisia", "Salt Lake City, Utah, USA")
    op <- par(mfrow = c(1, 3))
    for (p in places) {
      g <- ox_graph_from_address(p, dist = 800, network_type = "drive") |>
        ox_simplify()
      ox_plot_figure_ground(g, title = p)
    }
    par(op)

Use `ox_graph_from_point()` with a fixed `dist` (e.g. 805 m ≈ half a mile) to crop every city to the same one-square-mile window.

## References

Boeing, G. (2025). Modeling and analyzing urban networks and amenities with OSMnx. Geographical Analysis.

Boeing, G. (2021). Spatial information and the legibility of urban form. International Journal of Information Management 56.