Calculate Resources

Calculates planar volume and grade content from aligned, single-layer rasters in a projected metre CRS. Polygon intersections weight each cell by its exact covered fraction; missing grade or thickness excludes the cell from all totals.

Usage

calc_res(raster_grade, raster_thickness, area, density = 1)

Arguments

raster_grade

A single-layer SpatRaster of grade values.

raster_thickness

An aligned single-layer SpatRaster of thickness in metres.

area

An sf or sfc polygon boundary in the same projected metre CRS.

density

A positive finite conversion factor (default 1). For grade in kg/m3 use 1; for mass-fraction grade and density in t/m3 the result is tonnes. Convert percentages to fractions before using that second convention.

Value

A list containing the per-cell content raster and a polygon table. Area is valid covered area in m2, volume is in m3, thickness is area-weighted, grade is volume-weighted, and metal_content sums covered per-cell content. Polygons without valid intersecting cells have zero totals and NA means.

Details

Cell area is x resolution times y resolution. Area is measured in the map projection, not geodesic ground area; choose a suitable local CRS. The caller must supply compatible grade and density units. The result is preliminary numerical screening, not a reporting classification.