Caravaggio’s Bacco (1597)

Map Pan & Zoom III

A world map rendered on a Canvas element supports pan and zoom interactions via the d3.behavior.zoom API. The map uses pre-projected geographic geometry from a TopoJSON file, with d3.geo.path using a null projection so that only the canvas transform changes during zoom, avoiding re-projection. Country boundaries and land masses are drawn as filled and stroked paths, with strokes scaled inversely to maintain constant width.

58% match

Map Pan & Zoom I

A black-and-white world map renders on a light gray background using the Mercator projection. This example demonstrates map panning and zooming through the `d3.behavior.zoom` API, which applies SVG transforms to a group containing the geographic paths. The map is built from TopoJSON world data with `d3.geo.path`, and the zoom scale is limited to 1–8×. A transparent overlay rect captures pointer events, enabling the interactive behavior.

58% match

Map Zooming III

A map of the United States is drawn with canvas, and moving the mouse horizontally smoothly interpolates between three zoom levels centered on San Francisco, New Orleans, and New York. The example uses a linear scale with `d3.interpolateZoom` to map mouse position to a zooming transform, and `d3.geo.transform` for simplification. It renders TopoJSON state boundaries clipped by `d3.geo.clipExtent`, using D3 v3’s `d3.geo.path` with a canvas context.

Zoomable Map Tiles

This interactive map shows a zoomable view of OpenStreetMap tiles that smoothly pans and zooms across geographic regions. It uses the `d3.geo.tile` plugin to calculate which 256x256 tile images are visible in the viewport based on current scale and translate values, while `d3.behavior.zoom` handles user panning and zooming interactions. The tiles are rendered as `img` elements positioned absolutely, and a `d3.geo.mercator` projection inverts mouse coordinates to display the latitude and longitude at the cursor.

Pixymaps (Scrolling)

A scrolling map of San Francisco pans continuously leftward, with a tile-based image rendered to a Canvas element. The example uses the `pixymaps` library to manage view coordinates and tile loading, while the D3.js timer drives a subtle acceleration that increases scroll speed. Map tiles are loaded from CloudMade, and the view is projected using `d3.geo.mercator` to center the map. The animation updates the canvas by panning the view and re-rendering the image each frame.

Map Pan & Zoom II

This example demonstrates interactive pan and zoom on a world map using a dynamic Mercator projection. The map renders country landmasses as black paths, with white boundaries and a light gray sphere background, all within an SVG element. Using the `d3.behavior.zoom` API, user drag or scroll actions trigger reprojection and redraw the geospatial data via `d3.geo.path`. The underlying geographic data is loaded as JSON from a gist, and the projection translates and scales dynamically with each zoom event.

Van Wijk & Nuij Zooming

This example demonstrates a smooth and efficient zooming and panning animation for interactive maps, based on the algorithm by Van Wijk and Nuij. It uses Polymaps to render Bing Maps imagery and animates the map's center and zoom level over time. The JavaScript code calculates a path between two map states, applying logarithmic interpolation to create a natural, accelerated motion. The animation is triggered by a search query, which finds a location and animates the map to focus on it.

56% match

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.