map-projection

Identify optimal map projections for sphere-to-plane geospatial data transformations using distortion metrics like Tissot's indicatrix.

60|13|Updated Dec 22, 2025
One-click install
npx skills add https://github.com/plurigrid/asi --skill map-projection
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: map-projection
Source: https://github.com/plurigrid/asi/tree/main/skills/map-projection
Command: npx skills add https://github.com/plurigrid/asi --skill map-projection

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

This Skill provides a category-theoretic framing for map projections and the distortions introduced by forward/inverse transformations; supports comparative analysis and coloring via GF(3).

Core Features & Use Cases

  • Implement projection classes (Mercator, Lambert Azimuthal, Stereographic)
  • Compute and analyze Tissot's indicatrix for distortion
  • Natural transformations between projections and color-coding via GF(3)

Quick Start

Instantiate a projection (e.g., Mercator), project a sample point, and assign a GF(3) color seed to visualize distortion.

Frequently Asked Questions about map-projection

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I choose the right map projection for transforming geospatial data from sphere to plane?

Map projections transform spherical geographic data onto a 2D plane, each introducing different distortions. Selection depends on your region's scale and purpose: conformal projections preserve angles, equal-area preserve total area, equidistant preserve distance from center, and compromise projections balance multiple properties. This Skill helps you identify optimal projections for global, regional, or local data and analyze their distortion trade-offs.

What is Tissot's indicatrix and how does it measure projection distortion?

Tissot's indicatrix visualizes how a projection distorts infinitesimal circles on the sphere into ellipses on the plane. It quantifies local scale, angle, and area distortion at any map location. This Skill computes indicatrix metrics to reveal where your chosen projection performs well or poorly, enabling data-driven decisions about projection fit and visualization design.

Can I apply forward and inverse coordinate transformations with distortion analysis?

Yes. This Skill supports both forward transformations (sphere to plane) and inverse transformations (plane back to sphere), paired with distortion metric calculations. You can project geospatial coordinates, compute Tissot indicatrix values at those locations, and categorize projections by type—all within a unified workflow for comparative analysis and cartographic design.

How does category theory and GF(3) apply to map projections?

Category theory provides a formal framework for understanding natural transformations between different projections. GF(3)-aware coloring uses mathematical structures to encode and visualize distortion patterns systematically. This Skill leverages both to enable data-driven color-coding of projection properties, making distortion analysis and projection comparison more rigorous and interpretable.

What projection types does this Skill support?

This Skill implements conformal (Mercator, Stereographic), equal-area (Lambert Azimuthal), equidistant, and compromise projection classes. You can instantiate any projection type, apply forward/inverse transformations, compute distortion metrics, and categorize results. Support spans global, regional, and local scales for flexible geospatial analysis.

Can I visualize projection distortion across different map regions?

Yes. By computing Tissot's indicatrix at sample points across your study area and applying GF(3)-based coloring, you can visualize distortion intensity and type spatially. This Skill generates distortion maps that reveal which regions suffer angle loss, area compression, or distance scaling—critical for cartographic design and projection selection across scales.