image_shp {pliman}

Construct a shape file from an image

Description

Creates a list of object coordinates given the desired number of nrow and columns. It starts by selecting 4 points at the corners of objects of interest in the plot space. Then, given nrow and ncol, a grid is drawn and the objects' coordinates are returned.

Usage

image_shp(
  img,
  nrow = 1,
  ncol = 1,
  buffer_x = 0,
  buffer_y = 0,
  interactive = FALSE,
  viewer = get_pliman_viewer(),
  col_line = "red",
  size_line = 2,
  col_text = "red",
  size_text = 1,
  plot = TRUE
)

Arguments

img

An object of class Image

nrow

The number of desired rows in the grid. Defaults to 1.

ncol

The number of desired columns in the grid. Defaults to 1.

buffer_x, buffer_y

Buffering factor for the width and height, respectively, of each individual shape's side. A value between 0 and 0.5 where 0 means no buffering and 0.5 means complete buffering (default: 0). A value of 0.25 will buffer the shape by 25% on each side.

interactive

If FALSE (default) the grid is created automatically based on the image dimension and number of rows/columns. If interactive = TRUE, users must draw points at the diagonal of the desired bounding box that will contain the grid.

viewer

The viewer option. If not provided, the value is retrieved using get_pliman_viewer(). This option controls the type of viewer to use for interactive plotting. The available options are "base" and "mapview". If set to "base", the base R graphics system is used for interactive plotting. If set to "mapview", the mapview package is used. To set this argument globally for all functions in the package, you can use the set_pliman_viewer() function. For example, you can run set_pliman_viewer("mapview") to set the viewer option to "mapview" for all functions.

col_line, col_text

The color of the line/text in the grid. Defaults to "red".

size_line, size_text

The size of the line/text in the grid. Defaults to 2.5.

plot

Plots the grid on the image? Defaults to TRUE.

Value

A list with row * col objects containing the plot coordinates.

Examples

library(pliman)
flax <- image_pliman("flax_leaves.jpg")
shape <- image_shp(flax, nrow = 3, ncol = 5)