figure_ground.R

# load libraries
library(units)
library(tidyverse)
library(osmdata)
library(sf)
library(ggtext)
library(exactextractr)
library(fasterize)
library(ggtext)
library(tidygeocoder)
library(glue)
library(purrr)
library(geosphere)
library(classInt)
library(patchwork)
library(glue)

sf::sf_use_s2(TRUE)

#epsg <- 32632
epsg <- 4326
country <- 'germany'

aoi_citys <- c('Berlin, Germany',
  'Hamburg⁠, Germany',
  'München, Germany',
  'Köln, Germany',
  'Frankfurt, Germany',
  'Stuttgart, Germany',
  'Kiel, Germany',
  'Leipzig, Germany',
  'Dortmund, Germany')

figureground <- map_dfr(aoi_citys, function(aoi_city){

  city <- tidygeocoder::geo(aoi_city)  %>%
    st_as_sf(coords = c("long", "lat"), crs = 4326) %>%
    st_transform(epsg)

  buildings <- getbb(aoi_city)%>%
    opq(timeout = 100)%>%
    add_osm_feature(key = "building",
                    value = c("apartments",
                              "detached",
                              "dormitory",
                              "farm",
                              "hotel",
                              "house",
                              "residential",
                              "semidetached_house"
                    )) %>%
    osmdata_sf()


  buildings_sf <- buildings$osm_polygons %>%
    st_transform(epsg)


  crop_buffer <- st_buffer(city, 7500)

  buildings_sf <- st_crop(buildings_sf, crop_buffer)
  buildings_sf <- st_intersection(buildings_sf, crop_buffer)

  buildings_area <- as.numeric(sum(st_area(buildings_sf)))
  buffer_area <- as.numeric(sum(st_area(crop_buffer))) - buildings_area
  total_area <- as.numeric(sum(st_area(crop_buffer)))

  df <- tibble(x = c(1, 2),
                   type = c("Void", "Solid"),
                   city = rep(factor(aoi_city), 2),
                   count = c(buffer_area, buildings_area)) |>
         mutate(count = as.numeric(count))

  circleFun <- function(center=c(0,0), diameter=1, npoints=500, start=0, end=2, type, aoi, coverage_figure = NA, coverage_ground = NA)
  {
    tt <- seq(start*pi, end*pi, length.out=npoints)
    data.frame(x = center[1] + diameter / 2 * cos(tt),
               y = center[2] + diameter / 2 * sin(tt),
               type = type,
               aoi = aoi,
               coverage_figure = coverage_figure,
               coverage_ground = coverage_ground)
  }

  half_circles_solid <- circleFun(c(0,7.625),
                                  sqrt(buildings_area),
                                  start=0.5,
                                  end=1.5,
                                  type = "Solid",
                                  aoi = aoi_city,
                                  coverage_figure = round(buildings_area / total_area * 100, 2))

  half_circles_void <- circleFun(c(0,7.625),
                                 sqrt(buffer_area),
                                 start=1.5,
                                 end=2.5,
                                 type = "Void",
                                 aoi = aoi_city,
                                 coverage_ground = round(buffer_area / total_area * 100, 2))

  rbind(half_circles_solid,
             half_circles_void)

})

figureground |>
  arrange(aoi) |>
  ggplot() +
      geom_polygon(aes(x,y, fill = type)) +
      scale_fill_manual(values = c("#ad9a8c", "#f1eeeb")) +
      facet_wrap(vars(aoi)) +
      scale_x_continuous(expand = expansion(mult = c(0.1, .1))) +
      # annotate("richtext",
      #          x = -4000,
      #          y = 250,
      #          label.color = NA,
      #          fill = NA,
      #          hjust = 0.5,
      #          label = glue("<span style='text-align: center;'><b style = 'font-size:16pt; font-weight: 100;'>{coverage_ground} %</b> <br> Solid</span>")) +
      # annotate("richtext",
      #          x = 8000,
      #          y = 250,
      #          label.color = NA,
      #          fill = NA,
      #          hjust = 0.5,
      #          label = glue("<span style='text-align: center;'><b style = 'font-size:16pt; font-weight: 100;'>{coverage_figure} %</b> <br> Void</span>")) +
      coord_equal() +
      theme_void() +
      theme(legend.position = "none",
            panel.spacing.y = unit(1, "lines"),
            #plot.margin = margin(2, 2, 2, 2, "cm"),
            strip.text.x = element_text(size = 9, face = "bold"),
            text = element_text(family="West"))

wrapper <- function(label, dev_width = dev.size("in")[1], dev_scaler = 18)  {
  paste(strwrap(label, dev_width * dev_scaler), collapse = "\n")
}


figureground |>
  arrange(aoi) |>
  ggplot() +
  geom_polygon(aes(x,y, fill = type)) +
  scale_fill_manual(values = c("#ad9a8c", "#f1eeeb")) +
  facet_wrap(vars(aoi)) +
  scale_x_continuous(expand = expansion(mult = c(0.1, .1))) +
  guides(fill = guide_legend(keyheight = unit(1, units = "mm"),
                             keywidth = unit(5, units = "mm"),
                             direction = "horizontal",
                             nrow = 1,
                             ticks.colour = "white",
                             label.position = "bottom",
                             title.position = "bottom",
                             title.hjust = 0.5)) +
  coord_equal() +
  theme_void() +
  labs(title = "Figure Ground",
       subtitle = "The figure-ground diagram serves as a mapping technique that showcases the \n correlation between developed and undeveloped areas within urban environments.  \n This method visually represents the land occupied by buildings as a solid mass or 'figure', \n while the open spaces, including streets, parks, and plazas, are depicted as voids or ground. \n Here, we look at the 9 biggest German cities.",
       caption = "Data: OSM | Visualisation: Marco Sciaini",
       fill='') +
  theme(legend.direction="horizontal",
        legend.position="bottom",
        legend.box = "vertical",
        panel.spacing.y = unit(1, "lines"),
        plot.title = element_text(size = 18,
                                  colour = '#171717',
                                  hjust = 0.5,
                                  margin = margin(.3,0,.5,-2, "cm")),
        plot.subtitle = element_text(size = 9,
                                     colour = '#171717',
                                     hjust = 0.5,
                                     margin = margin(.3,0,.5,-2, "cm"),
                                     lineheight = 1.3),
        plot.caption = element_text(size = 6,
                                        colour = '#171717',
                                        margin = margin(.3,-2,.3,0, "cm")),
        strip.text.x = element_text(size = 7, face = "bold"),
        text = element_text(family="West"))

ggsave("single.png", width = 9, height = 16, dpi = 600) 

figureground_sf <- map(aoi_citys, function(aoi_city){

  city <- tidygeocoder::geo(aoi_city)  %>%
    st_as_sf(coords = c("long", "lat"), crs = 4326) %>%
    st_transform(epsg)

  buildings <- getbb(aoi_city)%>%
    opq(timeout = 100)%>%
    add_osm_feature(key = "building",
                    value = c("apartments",
                              "detached",
                              "dormitory",
                              "farm",
                              "hotel",
                              "house",
                              "residential",
                              "semidetached_house"
                    )) %>%
    osmdata_sf()

  buildings_sf <- buildings$osm_polygons %>%
    st_transform(epsg)

  crop_buffer <- st_buffer(city, 7500)

  buildings_sf <- st_crop(buildings_sf, crop_buffer)
  buildings_sf <- st_intersection(buildings_sf, crop_buffer)

  list(buildings_sf, crop_buffer)

})


street_plot <- ggplot() +
  geom_sf(data = figureground_sf[[1]][[2]], color = "#f1eeeb", fill = "#f1eeeb", lwd = .25, alpha = 0.8) +
  geom_sf(data = figureground_sf[[1]][[1]], color = "#ad9a8c", lwd = .15, alpha = 0.6) +
  theme_void()
street_plot

n_buildings <- nrow(figureground_sf[[1]][[1]])

coverage_figure <- figureground |>
  filter(aoi == "Berlin, Germany") |>
  pull(coverage_figure) |>
  unique() |>
  na.omit()

coverage_ground <- figureground |>
  filter(aoi == "Berlin, Germany") |>
  pull(coverage_ground) |>
  unique() |>
  na.omit()

circle_plot <- figureground |>
  filter(aoi == "Berlin, Germany") |>
  ggplot() +
  geom_polygon(aes(x,y, fill = type)) +
  scale_fill_manual(values = c("#ad9a8c", "#f1eeeb")) +
  scale_x_continuous(expand = expansion(mult = c(0.14, .14))) +
  guides(fill = guide_legend(keyheight = unit(1, units = "mm"),
                             keywidth = unit(5, units = "mm"),
                             direction = "horizontal",
                             nrow = 1,
                             ticks.colour = "white",
                             label.position = "bottom",
                             title.position = "bottom",
                             title.hjust = 0.5)) +
  coord_equal() +
  theme_void() +
  labs(#title = glue("{aoi_citys[1]} | {n_buildings} Buildings"),
       caption = "Data: OSM | Visualisation: Marco Sciaini",
       fill='') +
  annotate("richtext",
           x = -3000,
           y = 250,
           label.color = NA,
           fill = NA,
           hjust = 0.5,
           label = glue("<span style='text-align: center;'><b style = 'font-size:16pt; font-weight: 100;'>{coverage_figure} %</b> <br> Solid</span>")) +
  annotate("richtext",
           x = 7200,
           y = 250,
           label.color = NA,
           fill = NA,
           hjust = 0.5,
           label = glue("<span style='text-align: center;'><b style = 'font-size:16pt; font-weight: 100;'>{coverage_ground} %</b> <br> Void</span>")) +
  theme(legend.direction="horizontal",
        legend.position="bottom",
        legend.box = "vertical",
        panel.spacing.y = unit(1, "lines"),
        plot.title = element_text(size = 18,
                                  colour = '#171717',
                                  hjust = 0.5,
                                  margin = margin(.3,0,.5,-2, "cm")),
        plot.subtitle = element_text(size = 9,
                                     colour = '#171717',
                                     hjust = 0.5,
                                     margin = margin(.3,0,.5,-2, "cm"),
                                     lineheight = 1.3),
        plot.caption = element_text(size = 12,
                                    colour = '#171717',
                                    margin = margin(.3,-2,.3,0, "cm")),
        strip.text.x = element_text(size = 7, face = "bold"),
        text = element_text(family="West"))

street_plot + circle_plot + plot_annotation(
  title = glue("{aoi_citys[1]} | {n_buildings} Buildings"),
  theme = theme(        plot.title = element_text(size = 18,
                                                  face = "bold",
                                                  colour = '#171717',
                                                  hjust = 0.5,
                                                  margin = margin(.3,0,.5,-2, "cm")))
)
ggsave("both.png", width = 16, height = 9, dpi = 600)