set/get the canvas of the rayshader-ratrix project
raytrix_set_canvas.RdTo enable the downloading of rayshader-readable data for a desired extent,
it is necessary to set the rayshader-ratrix scene canvas using one of the
set_canvas_x() functions. See details for additional info.
Usage
set_canvas(bounds, projection)
set_canvas_world(projection = "+proj=longlat +datum=WGS84")
set_canvas_sf(.sf, mask = F)
set_canvas_raster(.raster, mask = F)
set_canvas_centroid(
lat,
long,
radius = 5000,
projection = "+proj=longlat +datum=WGS84"
)
get_canvas(res)
canvasExent()Arguments
- bounds
numeric vector of length 4. e.g.
c(xmin, xmax, ymin, ymax)- projection
...
- .sf
The sf/sfc object used to set the extent and projection of the canvas
- mask
Default is F. NOT WORKING YET!
- .raster
The raster object used to set the extent and projection of the canvas
- lat
...
- long
...
- radius
...
- res
A resolution (i.e pixel dimensions) in the units of the canvas crs (
get_canvas()$)
Details
set_canvas() offers the most control over the extent and projection of the
raytrix canvas. Use set_canvas_world() for a basic WGS84 extent of the
world; this is deliberately simple, for alternative global projections use
set_canvas(). set_canvas_sf() sets the canvas from an sf or sfc object;
this can be especially useful when you intend to plot sf features as
overlays. set_canvas_centroid() allows for the provision of lat long
coordinates and a buffer (in meters) around that point to set the extent;
this function takes WGS84 coords by default (although this can be changed)
but will always convert to Pseudo Mercator for convenience. To retrieve this
information use get_canvas() which returns a list including: extent,
projection and (if res is provided) dimension. canvasExent() returns
a raytrix extent object which is a copy of a raster Extent object. This can
be used in combination with rayshader functions such as
generate_polygon_overlay() to provide the extent of the topography matrix.
Examples
# set canvas with Universal Polar Stereographic
set_canvas(c(-4e7, 4e7, -4e7, 4e7 ),'+proj=ups')
get_canvas()
#> $extent
#> [1] -4e+07 4e+07 -4e+07 4e+07
#>
#> $projection
#> [1] "+proj=ups"
#>
get_canvas(4e4)
#> $extent
#> [1] -4e+07 4e+07 -4e+07 4e+07
#>
#> $projection
#> [1] "+proj=ups"
#>
#> $dimension
#> x y
#> 2000 2000
#>
# set canvas with tilted perspective...
set_canvas(c(-3.8e6, 3.8e6, -3.8e6, 3.8e6 ),'+proj=tpers +h=5500000 +lat_0=40')
get_canvas(4e4)
#> $extent
#> [1] -3800000 3800000 -3800000 3800000
#>
#> $projection
#> [1] "+proj=tpers +h=5500000 +lat_0=40"
#>
#> $dimension
#> x y
#> 190 190
#>
# set WGS84 global extent
set_canvas_world()
get_canvas(0.7)
#> $extent
#> [1] -180 180 -90 90
#>
#> $projection
#> [1] "+proj=longlat +datum=WGS84"
#>
#> $dimension
#> x y
#> 515 258
#>
# set canvas for Mt. St Helens
set_canvas_centroid(46.200732, -122.187082, radius = 7000)
#> Warning: `set_canvas_centroid() `converts coordinates to web mercator for convnience.to set a specific canvas extent and projection use `set_canvas()`
get_canvas(10)
#> $extent
#> xmin xmax ymin ymax
#> -13608804 -13594804 5805575 5819575
#>
#> $projection
#> [1] "PROJCRS[\"WGS 84 / Pseudo-Mercator\",\n BASEGEOGCRS[\"WGS 84\",\n DATUM[\"World Geodetic System 1984\",\n ELLIPSOID[\"WGS 84\",6378137,298.257223563,\n LENGTHUNIT[\"metre\",1]]],\n PRIMEM[\"Greenwich\",0,\n ANGLEUNIT[\"degree\",0.0174532925199433]],\n ID[\"EPSG\",4326]],\n CONVERSION[\"Popular Visualisation Pseudo-Mercator\",\n METHOD[\"Popular Visualisation Pseudo Mercator\",\n ID[\"EPSG\",1024]],\n PARAMETER[\"Latitude of natural origin\",0,\n ANGLEUNIT[\"degree\",0.0174532925199433],\n ID[\"EPSG\",8801]],\n PARAMETER[\"Longitude of natural origin\",0,\n ANGLEUNIT[\"degree\",0.0174532925199433],\n ID[\"EPSG\",8802]],\n PARAMETER[\"False easting\",0,\n LENGTHUNIT[\"metre\",1],\n ID[\"EPSG\",8806]],\n PARAMETER[\"False northing\",0,\n LENGTHUNIT[\"metre\",1],\n ID[\"EPSG\",8807]]],\n CS[Cartesian,2],\n AXIS[\"easting (X)\",east,\n ORDER[1],\n LENGTHUNIT[\"metre\",1]],\n AXIS[\"northing (Y)\",north,\n ORDER[2],\n LENGTHUNIT[\"metre\",1]],\n USAGE[\n SCOPE[\"unknown\"],\n AREA[\"World - 85°S to 85°N\"],\n BBOX[-85.06,-180,85.06,180]],\n ID[\"EPSG\",3857]]"
#>
#> $dimension
#> x y
#> 1400 1400
#>
# set canvas with sf object.
library(sf)
#> Linking to GEOS 3.8.0, GDAL 3.0.4, PROJ 6.3.1
demo(nc, ask = FALSE, echo = FALSE)
#> Reading layer `nc.gpkg' from data source
#> `/home/runner/work/_temp/Library/sf/gpkg/nc.gpkg' using driver `GPKG'
#> Simple feature collection with 100 features and 14 fields
#> Attribute-geometry relationship: 0 constant, 8 aggregate, 6 identity
#> Geometry type: MULTIPOLYGON
#> Dimension: XY
#> Bounding box: xmin: -84.32385 ymin: 33.88199 xmax: -75.45698 ymax: 36.58965
#> Geodetic CRS: NAD27
set_canvas_sf(nc)
#> Warning: Canvas projection is not cartesian.Be careful of the units you use to specify `res`!
get_canvas(7e-3)
#> $extent
#> xmin xmax ymin ymax
#> -84.32385 -75.45698 33.88199 36.58965
#>
#> $projection
#> [1] "GEOGCRS[\"NAD27\",\n DATUM[\"North American Datum 1927\",\n ELLIPSOID[\"Clarke 1866\",6378206.4,294.978698213898,\n LENGTHUNIT[\"metre\",1]]],\n PRIMEM[\"Greenwich\",0,\n ANGLEUNIT[\"degree\",0.0174532925199433]],\n CS[ellipsoidal,2],\n AXIS[\"geodetic latitude (Lat)\",north,\n ORDER[1],\n ANGLEUNIT[\"degree\",0.0174532925199433]],\n AXIS[\"geodetic longitude (Lon)\",east,\n ORDER[2],\n ANGLEUNIT[\"degree\",0.0174532925199433]],\n USAGE[\n SCOPE[\"unknown\"],\n AREA[\"North America - NAD27\"],\n BBOX[7.15,167.65,83.17,-47.74]],\n ID[\"EPSG\",4267]]"
#>
#> $dimension
#> x y
#> 1267 387
#>
canvasExent()
#> An object of class "Extent"
#> Slot "xmin":
#> xmin
#> -84.32385
#>
#> Slot "xmax":
#> xmax
#> -75.45698
#>
#> Slot "ymin":
#> ymin
#> 33.88199
#>
#> Slot "ymax":
#> ymax
#> 36.58965
#>