Hilbert Tiles

Sequential Tiles

This example demonstrates a rainbow-colored tile grid that visualizes the sequence of map tiles in a web mapping interface. Each tile at a given zoom level is assigned a color based on its sequential position, creating a visible gradient that shows the order and layout of map tiles. The visualization uses the Polymaps JavaScript library’s `po.map()` and `po.layer()` APIs, with a custom `rainbow` function that calculates a hue from the tile’s column and row indices. The code also includes a custom `hsl` function for color conversion, and the map is configured with a 32x32 tile size and zoom level 4.

76% match

Hilbert paths

A colorful, animated SVG visualization of Hilbert curves traces a path through a 512×512 grid, with the curve segmented into randomly sized, color-coded strokes. A white outline shows the full curve while seven white circles jump along it, updating their positions and a coordinate readout via `d3.interval`. The code uses `d3.scaleOrdinal` for color, `d3.range` for path generation, and custom `d2xy` and `xy2d` functions to map between Hilbert curve indices and 2D coordinates. Built with d3.v4 and SVG.

PPhilippe Rivière

73% match

Heatmap

This heatmap blends a base map with three point locations that are transformed into radial gradients, showing how they are highlighted on a map. The visualization combines a CloudMade tile layer and OpenStreetMap data, with the points loaded as GeoJSON features. The map uses the Polymaps library, and its `load` callback dynamically adjusts each point’s radius based on the current zoom level while assigning a green gradient fill with fading opacity.

63% match

Tile Viewer

This example shows a zoomable map interface where the user can pan and zoom across geographic tiles. It displays each tile as a numbered 256-by-256-pixel square with a red border and its coordinates as text, updating the visible grid as the viewport changes. The code uses d3.geo.tile, d3.geo.mercator, and d3.behavior.zoom, applying a CSS 3D matrix transform to reposition tiles during zoom events. It relies on a gist by mbostock and the d3.v3 library, with tile positions computed from the current zoom scale and translation.

63% match

Vector Tiles

This example displays a static vector-tile map of San Francisco’s roads, with major highways, minor roads, and rail lines rendered as stylized SVG strokes. Using D3 v3, it loads Mapzen’s OpenStreetMap “roads” tiles via `d3.json`, sorts features by `sort_key`, and draws each path with `d3.geo.path` and a Mercator projection. A custom `d3.geo.tile` helper computes the visible tile range and scale, while CSS classes like `.highway` and `.rail` assign distinct colors and widths.

d3-tile wrapping

This example displays an interactive SVG world map using tiled raster images from OpenStreetMap, with tile-wrapping toggled by a checkbox. The visualization relies on the `d3-tile` library’s `tile.wrap` method to generate tile coordinates, and `d3.geoMercator` with `d3.geoPath` for the projection. An HTML form checkbox controls the `wrap` flag, triggering a `loadTiles` function that rebuilds the image layer. Each tile is fetched from the `a.b.c.tile.openstreetmap.org` subdomains. The map’s scale and translation are computed and applied via SVG group transforms.

CCurran Kelleher

Image Processing

This example demonstrates real-time image processing on map tiles using Polymaps and HTML5 Canvas. The map loads a static image from a URL and renders it through a custom canvas layer, where each tile’s pixel data is read with `getImageData` and halved in intensity before being written back via `putImageData`. The code uses `po.canvas()` to define the layer, `drawImage` to place the source, and `createImageData` to prepare the output. The result shows a visibly darkened version of the original image across the panning map.

Tile by Bounding Box

This example demonstrates how to automatically position map tiles from OpenStreetMap to fit a specified geographic bounding box, using a Mercator projection. The code calculates the necessary scale and translation to center the bounding box, adjusts the projection with `d3.geoMercator()`, and generates the appropriate tile URLs via `d3.tile()`. A vector outline of US states, rendered with `d3.geoPath()`, is overlaid on the raster tiles to show the projection's alignment.

CCurran Kelleher