Package index • tissot

Distortion metrics

Compute Tissot indicatrix properties at arbitrary points or over a regular projected grid. Returns scale factors, angular deformation, areal distortion, and convergence.

tissot(): Compute Tissot indicatrix properties
tissot_raster() image(<tissot_raster>) plot(<tissot_raster>): Compute distortion surfaces on a regular grid

Indicatrix objects and plotting

Build indicatrix objects from distortion results, extract raw ellipse coordinates, and draw single or multiple indicatrixes on a map.

indicatrix(): Build Tissot indicatrix objects
`[`(<indicatrix_list>): Subset an indicatrix_list
ti_ellipse(): Generate ellipse coordinates for an indicatrix
plot(<indicatrix>): Plot an indicatrix
plot(<indicatrix_list>): Plot a list of indicatrixes

Raster distortion plots

Visualize a tissot_raster distortion surface with image() or plot().

tissot_raster() image(<tissot_raster>) plot(<tissot_raster>): Compute distortion surfaces on a regular grid

Map utilities

Add a world coastline overlay, reference ablines at given lon/lat positions, or convert projected coordinates back to geographic for use with tissot().

tissot_map() tissot_abline(): Plot world coastline on a projected map
tissot_unproject(): Unproject coordinates to geographic (lon/lat) CRS

Data

Bundled datasets used in examples.

world: World coastline

Deprecated

Superseded helpers for accessing the package-level projection state. Prefer passing target explicitly to tissot_map() and tissot_abline().

tissot_get_proj() tissot_set_proj(): Get or set the current plot projection