To see more complete package documentation check out: https://pfrater.github.io/arcpullr/
knitr::opts_chunk$set( collapse = TRUE, comment = "#>" ) options(rmarkdown.html_vignette.check_title = FALSE) library(arcpullr) library(sf)
#<img src='../man/figures/logo.png' width="160" height="180" style="border: none; float: right"/>
arcpullr
has the capability to query not only vector (Feature) layers, but
also raster layers (both Map and Image service types). The syntax for these is
generally the same as for the get_layer_by_*
family of functions. Map and
Image layers require a bounding box as part of the query, so both
get_map_layer
and get_image_layer
have required arguments of a URL and an
sf
object. These functions pull the raster layers provided by the URL and return the layer as a RasterLayer object from the raster
package.
# WDNR Server image_server <- "https://dnrmaps.wi.gov/arcgis_image/rest/services/" # WI Landcover Type URL landcover_path <- "DW_Land_Cover/EN_Land_Cover2_Lev2/MapServer" landcover_url <- paste0(image_server, landcover_path) # WI Leaf-off Aerial Imagery URL wi_leaf_off_path <- "DW_Image/EN_Image_Basemap_Leaf_Off/ImageServer" wi_aerial_imagery_url <- paste0(image_server, wi_leaf_off_path) # the wis_poly polygon is available as an exported object in arcpullr
The get_map_layer
function takes a URL and an sf object. Since the query for
this layer type on an ArcGIS REST Service requires a bounding box any sf object
can be used (i.e. POLYGON, POINT, LINE, etc.) and a bounding box will be created
using the extent of the shape.
The example below pulls Wisconsin landcover types and plots them in a map.
wi_landcover <- get_map_layer(landcover_url, wis_poly)
plot_layer(wi_landcover)
The get_image_layer
function works the same as get_map_layer
except that it
queries from an Image layer. The easiest way to distinguish a Map layer from an
Image layer is by checking the URL. Those from images will end with
"ImageServer" whereas those from maps will end with "MapServer". Another way to
check is to look a the "Supported Operations" at the bottom of the actual web
page on the ArcGIS REST Service. It will say either "Export Image" or
"Export Map".
This example pulls with Wisconsin Leaf-off Aerial Imagery dataset from the Wisconsin Department of Natural Resources.
wi_aerial_imagery <- get_image_layer(wi_aerial_imagery_url, wis_poly)
plot_layer(wi_aerial_imagery)
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