Winding Order

winding problem

This visualization highlights the winding problem in GeoJSON polygons by coloring affected areas yellow, while correctly oriented polygons appear light blue. It uses d3.json to load Istanbul district boundaries and d3.geoPath with a Mercator projection to render them as SVG paths. The code checks each feature with d3.geoArea, reversing coordinate arrays for polygons exceeding 2π area, marking those features with an error property. The map shows these inverse-wound regions clearly, demonstrating how D3’s geo algorithms handle polygon orientation.

PPhilippe Rivière

71% match

geoCircle in d3.v4 (geoOrthographic)

This example visualizes concentric circles radiating from two geographic points—the North Pole and Washington, DC—using a d3.geoOrthographic projection. The circles, generated with d3.geoCircle, are drawn as SVG paths via d3.geoPath, with radii incrementing from 5 to 85 degrees. The map includes land masses rendered from TopoJSON world data, styled with fills and strokes. The code loads d3.v4 and topojson.v1 from CDNs, and the interaction between the circle generator and projection demonstrates how to create geodesic rings on a globe-like view.

PPhilippe Rivière

70% match

Circular Layout (Recursive)

A circular layout visualizes ten concentric rings, each divided into 90 wedge-shaped segments. The example derives these shapes recursively, with each ring’s path geometry generated from radial distances scaled from 180 to 240 pixels and angular slices of π/90 radians. Colors interpolate from brown to steelblue across the rings. The implementation uses D3 v3’s linear scales for radius and fill, and builds SVG paths via `d3.svg.arc` within nested `selectAll` and `enter` calls. The data is procedural, created with `d3.range(10)` for rings and angle increments.

68% match

Counterclockwise Arc

Two d3.svg.arc paths illustrate the visual difference between clockwise and counterclockwise arc direction in D3 v3. The first arc runs from π/4 to 3π/4, while the second reverses those angles to create a counterclockwise sweep. Each path has a text label placed along its curve using SVG textPath, with the text following the arc’s direction. The example renders scalable vector graphics in an SVG container, using the arc generator’s startAngle and endAngle properties to define the geometry and orientation.

68% match

Rotating Orthographic

This rotating orthographic projection displays a graticule and the equator as animated SVG paths on a sphere. It uses the d3.geo.orthographic projection with a rotating view, updating the projection’s rotation based on a timed loop. The sphere, graticule, and equator are drawn as SVG paths via d3.geo.path, with the animation driven by d3.timer incrementally adjusting the rotation angles.

Rotating Orthographic

An orthographic projection of the world rotates continuously, showing a dark outline of the continents against a circular boundary. The rotation is driven by a timer that recalculates the projection’s center based on elapsed time and a fixed velocity. The example uses `d3.geo.orthographic()`, `d3.geo.path()`, and `topojson.feature()` to render the land from a `world-110m.json` dataset as SVG. The code also applies a 90-degree clip angle and updates the path’s `d` attribute on each tick, with styling from a CSS circle element.

Orthographic Grid

An orthographic grid of graticule lines at 10-degree intervals rotates slowly over time, demonstrating an azimuthal projection that resembles a globe viewed from space. The visualization uses D3 v3’s `d3.geo.orthographic`, `d3.geo.path`, and `d3.geo.graticule` to render SVG paths, while a `d3.timer` continuously updates the projection’s rotation based on a fixed velocity vector. A static circle outlines the globe’s edge, and the animation shows how latitude and longitude lines curve as the view shifts.

August Projection

This example displays a world map using the August projection, a pseudocylindrical equal-area projection that curves parallels and meridians into distinctive intertwined shapes. The map renders land masses in dark gray with white country boundaries overlaid on a graticule, all enclosed within a spherical outline. Using D3 v3, the code employs `d3.geo.august` for the projection, `d3.geo.path` to draw geographic features, and `d3.geo.graticule` for the grid. TopoJSON data provides the world land and country boundaries, loaded from an external JSON file.