用addWMSTiles加载R传单中的WMS层

Question

我试图在R传单包中添加WMS瓷砖--使用这个示例geoserver WMS没有问题：

leaflet() %>% addTiles() %>% setView(-93.65, 42.0285, zoom = 4) %>%  addWMSTiles(
"http://sedac.ciesin.columbia.edu/geoserver/wms",
layers = "energy:energy-pop-exposure-nuclear-plants-locations_plants",
options = WMSTileOptions(format = "image/png", transparent = TRUE),
tileOptions(tms = TRUE),
attribution = "")

然而，当我尝试使用来自国家地图的WMS时，尽管多次尝试为url和层设置参数，我还是继续获得空的传单结果：

leaflet() %>% addTiles() %>% setView(-93.65, 42.0285, zoom = 4) %>%addWMSTiles(
"http://basemap.nationalmap.gov/arcgis/services/USGSHydroNHD/MapServer/WmsServer?",
layers = "0",
options = WMSTileOptions(format = "image/png", transparent = TRUE),
attribution = "") 

我以前没有在R传单包外使用过传单，所以这可能是使用这种WMS在传单中设置参数时的一个新手错误。

Answer 1

你只需要放大一点点，图层就会出现。试试这个：

leaflet() %>% addTiles() %>% setView(-93.65, 42.0285, zoom = 7) %>%addWMSTiles(
"http://basemap.nationalmap.gov/arcgis/services/USGSHydroNHD/MapServer/WMSServer?",
layers = "0",
options = WMSTileOptions(format = "image/png", transparent = TRUE),
attribution = "")