makeChipsMultiClass

Generate image chips from images and associated raster masks for multiclass classification

Usage

makeChipsMultiClass(
  image,
  mask,
  n_channels = 3,
  size = 256,
  stride_x = 256,
  stride_y = 256,
  outDir,
  useExistingDir = FALSE
)

Arguments

image

SpatRaster object or path to input image. Function will generate a SpatRaster object internally. The image and mask must have the same extent, number of rows and columns of pixels, cell size, and coordinate reference system.

mask

SpatRaster object or path to single-band mask. Function will generate a SpatRaster object internally. The image and mask must have the same extent, number of rows and columns of pixels, cell size, and coordinate reference system.

n_channels

Number of channels in the input image. Default is 3.

size

Size of image chips as number of rows and columns of pixels. Default is 256.

stride_x

Stride in the x (columns) direction. Default is 256.

stride_y

Stride in the y (rows) direction. Default is 256.

outDir

Full or relative path to the current working directory where you want to write the chips to. Subfolders in this directory will be generated by the function if useExistingDir = FALSE. You must include the final forward slash in the file path (e.g., "C:/data/chips/").

useExistingDir

TRUE or FALSE. Write chips into an existing directory with subfolders already defined as opposed to using a new directory. This can be used if you want to add chips to an existing set of chips. Default is FALSE.

Value

Image and mask files written to disk in TIFF format. No R object is returned.

Details

This function generates image and mask chips from an input image and associated raster mask. The chips will be written into the defined directory. The number of rows and columns of pixels per chip are equal to the size argument. If a stride_x and/or stride_y is used that is different from the size argument, resulting chips will either overlap or have gaps between them. In order to not have overlap or gaps, the stride_x and stride_y arguments should be the same as the size argument. Both the image chips and associated masks are written to TIFF format (".tif"). Input data are not limited to three band images. This function is specifically for a multiclass classification. For a binary classification or when only two classes are differentiated, use the makeChips() function. If an irregular shaped raster grid is provided, only chips and masks that contain no NA or NoDATA cells will be produced.

Within the provided directory, image chips will be written to an "images" folder and masks will be written to a "masks" folder.

Examples

if (FALSE) {
makeChipsMultiClass(image = "INPUT IMAGE NAME AND PATH",
                    mask = "INPUT RASTER MASK NAME AND PATH",
                    n_channels = 3,
                    size = 512,
                    stride_x = 512,
                    stride_y = 512,
                    outDir = "DIRECTORY IN WHICH TO SAVE CHIPS",
                    useExistingDir=FALSE)
}