如何在 R Rayshader 中将多边形添加到 3D 地图？

Question

我是地理空间数据的新手，只是通过查看网络上的几篇文章来设法以小块的方式进行绘制。

我正在尝试在我使用 rayshader 包构建的 3D 图上绘制多边形边界，但面临问题，并在顶部显示显示多边形边界。

使用的形状文件是

2011_Dist.shp

，可以从Shapefile Github链接

下载

我尝试过的代码：

library(tidyverse)
library(sf)
library(elevatr)
library(raster)
library(rayshader)
library(osmdata)

# read districts shape file
ind_distirct_shp <- sf::st_read("local path/2011_Dist.shp")
ind_distirct_shp

# filter State
delhi_district_shp <- ind_distirct_shp %>% 
                       sf::st_as_sf() %>% 
                       filter(ST_NM %in% c("NCT of Delhi"))

# this shows the polygon boundaries that I need on top of map
plot(delhi_district_shp)

# download elevation data for State Delhi
delhi_raster <- elevatr::get_elev_raster(delhi_district_shp, z = 10, clip = "location")

# convert to matrix
delhi_mat <- raster_to_matrix(delhi_raster)

# 3D plot using Rayshader
delhi_mat %>%
  
  height_shade(texture = grDevices::colorRampPalette(c("#9a133d","orange","red","purple"
                                                       ))(256)) %>%
  plot_3d(heightmap = delhi_mat, 
          windowsize = c(800,800), # c(800*wr,800*hr) 
          solid = FALSE, 
          zscale = 1,
          phi = 90, 
          zoom = .6, 
          theta = 0,
          shadowcolor = "grey50",  
          linewidth = 6,
          background = "white",
          solidlinecolor = "#013b39") 

问题：现在，当我尝试修改此内容以添加

polygon lines

时，它不起作用。

polygon_layer = generate_polygon_overlay(delhi_district_shp, extent = extent(delhi_raster),
                                    heightmap = delhi_mat) # , palette="grey30"

polygon_layer

delhi_mat %>%
  
  height_shade(texture = grDevices::colorRampPalette(c("#9a133d","orange","red","purple"
                                                       ))(256)) %>% 
  add_overlay(polygon_layer) %>% 
  
  plot_3d(heightmap = delhi_mat, 
          windowsize = c(800,800), # c(800*wr,800*hr) 
          solid = FALSE, 
          zscale = 1,
          phi = 90, 
          zoom = .6, 
          theta = 0,
          shadowcolor = "grey50",  
          linewidth = 6,
          background = "white",
          solidlinecolor = "#013b39")

它应该是橙色 3D 地图顶部的多边形线，但它没有按我的预期工作。

2. 我还尝试了 Rayshder 的 tyler 网站示例 https://www.tylermw.com/adding-open-street-map-data-to-rayshader-maps-in-r/

library(osmdata)

osm_bbox = c(extent(delhi_raster)[3],extent(delhi_raster)[1],extent(delhi_raster)[4],extent(delhi_raster)[2])
osm_bbox

raster_polygon_boundary <- osmdata::opq(osm_bbox) %>% 
  add_osm_feature("highway") %>%  # "admin_level" 
  osmdata_sf()

raster_polygon_boundary

输出：

Object of class 'osmdata' with:
                 $bbox : 76.8425681832661,28.4030759258059,77.347719586084,28.8793200072187
        $overpass_call : The call submitted to the overpass API
                 $meta : metadata including timestamp and version numbers
           $osm_points : 'sf' Simple Features Collection with 0 points
            $osm_lines : NULL
         $osm_polygons : 'sf' Simple Features Collection with 0 polygons
       $osm_multilines : NULL
    $osm_multipolygons : NULL

我在上面得到0个多边形和线条，所以我无法在

3D图

之上添加任何polygon。

我该如何解决这个问题。感谢任何帮助。

Answer 1

将

alphalayer

添加到

add_overlay(polygon_layer,alphalayer = .6)

有所帮助，尽管它有效，但透明度仍然无法完美发挥作用。它在情节中造成了一些

whiteness

。如果其他人有更好的答案或改进方法，请随时分享。

delhi_mat %>%
  
  height_shade(texture = grDevices::colorRampPalette(c("#9a133d","orange","red","purple"
                                                       ))(256)) %>% 
  add_overlay(polygon_layer,alphalayer = .6) %>% 
  
  add_overlay(generate_label_overlay(delhi_district_shp, extent = extent(delhi_raster),
                                     text_size = 5, point_size = 1, 
                                     halo_color = "white",halo_expand = 5, 
                                     seed=1,
                                     heightmap = delhi_mat, data_label_column = "DISTRICT")) %>% 
  
  plot_3d(heightmap = delhi_mat, 
          windowsize = c(800,800), # c(800*wr,800*hr) 
          solid = FALSE, 
          zscale = .7,
          phi = 90, 
          zoom = .6, 
          theta = 0,
          shadowcolor = "grey50",  
          linewidth = 6,
          background = "white",
          solidlinecolor = "#013b39")

Answer 2

您可以通过创建自定义颜色（白色，100% 透明）来填充多边形来实现您想要的效果：

polygon_layer = generate_polygon_overlay(delhi_district_shp, 
                                         extent = extent(delhi_raster),
                                         heightmap = delhi_mat,
                                         palette = rgb(0,0,0,0)) # R,G,B,alpha