tissot: Tissot Indicatrix for Map Projection Distortion

Compute and visualize the 'Tissot Indicatrix' for map projections. The indicatrix characterizes projection distortion by computing scale factors, angular deformation, areal distortion, and convergence at arbitrary points. Based on the calculations shared by Bill Huber on <https://gis.stackexchange.com/a/5075/482>. Uses 'PROJ' for coordinate transformation and distortion factor computation. Developed using the method published in Snyder, JP (1987) <doi:10.3133/pp1395>.

Version: 0.3.0
Depends: R (≥ 3.6.0)
Imports: tibble, PROJ, graphics, grDevices, stats
Suggests: testthat (≥ 3.0.0), knitr, rmarkdown, spelling
Published: 2026-07-12
DOI: 10.32614/CRAN.package.tissot
Author: Michael Sumner ORCID iD [aut, cre, cph], Bill Huber [aut] (original algorithm and calculations)
Maintainer: Michael Sumner <mdsumner at gmail.com>
BugReports: https://github.com/hypertidy/tissot/issues
License: MIT + file LICENSE
URL: https://hypertidy.github.io/tissot/, https://github.com/hypertidy/tissot
NeedsCompilation: no
Language: en-US
Materials: README, NEWS
CRAN checks: tissot results

Documentation:

Reference manual: tissot.html , tissot.pdf

Downloads:

Package source: tissot_0.3.0.tar.gz
Windows binaries: r-devel: tissot_0.3.0.zip, r-release: tissot_0.2.0.zip, r-oldrel: tissot_0.2.0.zip
macOS binaries: r-release (arm64): tissot_0.3.0.tgz, r-oldrel (arm64): tissot_0.3.0.tgz, r-release (x86_64): tissot_0.3.0.tgz, r-oldrel (x86_64): tissot_0.3.0.tgz
Old sources: tissot archive

Linking:

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