Example: heterogeneous

crossing(
  x = seq(0, 1, 0.02),
  y = seq(0, 2, 0.02)
) |>
  mutate(intensity = our_lambda_fun(x, y)) |>
  ggplot(aes(x = x, y = y, fill = intensity)) +
  geom_tile() +
  scale_fill_viridis_c() +
  coord_fixed() +
  theme_minimal() +
  ggtitle("Chosen spatial\nintensity gradient")