ROI area

ROI area

Usage

at_roi_area(
  roi,
  level = 0L,
  units = c("px", "physical"),
  call = rlang::caller_env(),
  image = NULL
)

Arguments

roi

An annot_roi.

level

Integer pyramid level at which to express the area. Default 0.

units

Either "px" (pixels squared, the default) or "physical". Physical area uses image calibration at level zero, in squared image$pixel_unit, and is invariant to reporting level. Unknown or pixel-only image calibration rejects. Without an image, legacy ROI pixel_size=c(x,y) is supported at stored level zero, in squared calibration units. Nonzero ROI levels require explicit pixel_size_level and pixel_unit; differing calibration and stored levels require an image for the geometric transform. Pixel sizes must be finite and positive. Geometric area is not raster support count.

call

The calling environment, for error reporting.

image

Optional annot_image defining actual pyramid dimensions. Required when level differs from the ROI's stored level.

Value

A numeric scalar area, or NA_real_ for non-areal geometry (points, lines).

See also

Other rois: at_roi_bbox(), at_roi_centroid(), at_roi_circle(), at_roi_ellipse(), at_roi_freehand(), at_roi_from_geojson(), at_roi_from_sf(), at_roi_point(), at_roi_polygon(), at_roi_rect()

Examples

at_roi_area(at_roi_rect(0, 0, 10, 5, label = "a"))
#> [1] 50