| Type: | Package |
| Title: | Design Shaded Contour Lines (or Tanaka) Maps |
| Version: | 0.4.0 |
| Description: | The Tanaka method enhances the representation of topography on a map using shaded contour lines. In this simplified implementation of the method, north-west white contours represent illuminated topography and south-east black contours represent shaded topography. See Tanaka (1950) <doi:10.2307/211219>. |
| License: | GPL-3 |
| Imports: | terra, sf, mapiso, maplegend, grDevices, graphics |
| Encoding: | UTF-8 |
| RoxygenNote: | 7.2.3 |
| Suggests: | tinytest, covr, lwgeom |
| URL: | https://github.com/riatelab/tanaka/ |
| BugReports: | https://github.com/riatelab/tanaka/issues/ |
| NeedsCompilation: | no |
| Packaged: | 2023-11-28 15:43:22 UTC; tim |
| Author: | Timothée Giraud 
[cre, aut] |
| Maintainer: | Timothée Giraud <timothee.giraud@cnrs.fr> |
| Repository: | CRAN |
| Date/Publication: | 2023-11-28 17:40:02 UTC |
Tanaka Contours Package
Description
The tanaka package is a simplified implementation of the Tanaka method. Also called "relief contours method", "illuminated contour method", or "shaded contour lines method", the Tanaka method enhances the representation of topography on a map using shaded contour lines. North-west white contours represent illuminated topography and south-east black contours represent shaded topography.
Plot a Tanaka Map
Description
This function plots a tanaka map.
Usage
tanaka(
x,
nclass = 8,
breaks,
col,
mask,
light = "#ffffff70",
dark = "#00000090",
shift,
legend.pos = "left",
legend.title = "Elevation",
add = FALSE
)
Arguments
x |
a raster or an sf contour layer (e.g. the result of
|
nclass |
a number of class. |
breaks |
a vector of break values. |
col |
a color palette (a vector of colors). |
mask |
a mask layer, a POLYGON or MULTIPOLYGON sf object. |
light |
light shadow (NW color). |
dark |
dark shadow (SE color). |
shift |
size of the shadow (in map units). |
legend.pos |
position of the legend, one of 'topleft', 'top', 'topright', 'right', 'bottomright', 'bottom', 'bottomleft', 'left' or a vector of two coordinates in map units (c(x, y)). If leg.position = NA then the legend is not plotted. If leg.position = 'interactive' click on the map to choose the legend position. |
legend.title |
title of the legend. |
add |
whether to add the layer to an existing plot (TRUE) or not (FALSE). |
Value
A Tanaka contour map is plotted.
References
Tanaka, K. (1950). The relief contour method of representing topography on maps. Geographical Review, 40(3), 444-456.
Examples
library(tanaka)
library(terra)
library(sf)
com <- st_read(system.file("gpkg/com.gpkg", package = "tanaka"),
quiet = TRUE
)
ras <- rast(system.file("tif/elev.tif", package = "tanaka"))
tanaka(ras)
tanaka(ras, mask = com)
tanaka(ras,
breaks = seq(80, 400, 20),
legend.pos = "topright",
legend.title = "Elevation\n(meters)"
)
tanaka(ras,
nclass = 15,
col = hcl.colors(15, "YlOrRd"),
legend.pos = "topright",
legend.title = "Elevation\n(meters)"
)
Create a Contour Layer
Description
Create a contour layer.
Usage
tanaka_contour(x, nclass = 8, breaks, mask)
Arguments
x |
a raster object. |
nclass |
a number of class. |
breaks |
a vector of break values. |
mask |
a mask layer, a POLYGON or MULTIPOLYGON sf object. |
Value
A MULTIPOLYGON sf object is return. The data.frame contains 3 fields: id, min (minimum value of the raster in the MULTIPOLYGON) and max (maximum value of the raster in the MULTIPOLYGON).
Examples
library(tanaka)
library(terra)
library(sf)
ras <- rast(system.file("tif/elev.tif", package = "tanaka"))
iso <- tanaka_contour(x = ras)
plot(st_geometry(iso), col = c(
"#FBDEE1", "#F0BFC3", "#E7A1A6",
"#DD8287", "#D05A60", "#C03239",
"#721B20", "#1D0809"
))