tin2grid: Interpolate TIN-based mesh values to grid
In telemac: R Interface to the TELEMAC Model Suite

Description Usage Arguments Value Note Examples

Linearly interpolates the values of a mesh based on irregular triangles to a regular grid.

tin2grid(x, s, output, ...)

## S3 method for class 'data.frame'
tin2grid(
  x,
  s,
  output = c("data.frame", "list", "raster"),
  ...,
  col_x = "x",
  col_y = "y",
  col_z = "z",
  tinmat
)

## S3 method for class 't2d_geo'
tin2grid(
  x,
  s,
  output = c("data.frame", "list", "raster"),
  ...,
  v = "elevation"
)

## S3 method for class 't2d_res'
tin2grid(
  x,
  s,
  output = c("data.frame", "list", "raster"),
  ...,
  v = NULL,
  t = NULL
)

`x`	Either: a `data.frame` with mesh coordinates and elevations; an object of class `t2d_geo` or `t2d_res`.
`s`	`numeric` value defining the resolution of the output grid.
`output`	`character`, either: `"data.frame"` (default), `"list"`, or `"raster"` to return a `raster` object. If multiple variables `v` or timesteps `t` are given, a `data.frame` will be returned in any case.
`...`	Arguments passed to or from other methods.
`col_x`	If `x` is a `data.frame`: column with the x coordinates.
`col_y`	If `x` is a `data.frame`: column with the y coordinates.
`col_z`	If `x` is a `data.frame`: column with the mesh values.
`tinmat`	`integer` matrix of point indices (referring to x and y coordinates) defining the mesh elements (such as element `triangles` of a `t2d_tin` object).
`v`	`character`, name of the variable(s) that is/are to be extracted and interpolated (default all variables that can be found). If `x` is of class `t2d_geo` `elevation` will be taken by default.
`t`	`integer`, timestep(s) that is/are to be extracted and interpolated (default: all timesteps).

If output == "data.frame": A data.frame with:

x or col_x: X coordinates of the output grid
y or col_y: Y coordinates of the output grid
z or col_z: Interpolated values
variable: OPTIONAL (more than one given): imported variable the current values refer to
timestep: OPTIONAL (more than one given): simulation timestep the current values refer to

If output == "list": A list with:

x: X coordinates of the output grid
y: Y coordinates of the output grid
z: Matrix with interpolated values, where z[i,j] points to coordinates x[i] and y[j]

If output == "raster": An object of class raster.

If you import many variables or timesteps or the mesh is huge or s very small the resulting dataset might become excessively large (especially if output is a data.frame)!

If x is a data.frame, all input arguments referring to columns of x support quasiquotation, i.e. they can be specified by their names, quoted or unquoted, or as column position.

# plot model bathymetry with ggplot
library(raster)
library(sf)
library(tidyverse)
# t2d_geo object
bnd <- st_read(system.file("dem/boundary_lagos.gpkg", package = "telemac"))
tin_obj <- tin(list(boundary = bnd), s = 90, a = 100^2, q = 30)
dem_rast <- raster(system.file("dem/dem_merit_lagos.tif", package = "telemac"))
geo_obj <- geo(tin_obj, dem = dem_rast)
# interpolate to regular grid as df and plot
geo_df <- tin2grid(geo_obj, s = 90, output = "data.frame")
ggplot(geo_df, aes(x = x, y = y, fill = value)) +
  geom_raster() +
  coord_equal() +
  scale_fill_viridis_c()