TopoJSON (Topology-Aware JSON)
Open BetaTopoJSON, GeoJSON का एक टोपोलॉजी-जागरूक विस्तार है। यह साझा-चाप (shared-arc) एनकोडिंग (बहुभुजों के बीच की सीमाएँ केवल एक बार संग्रहीत) और निर्देशांकों के पूर्णांक क्वांटाइज़ेशन का उपयोग करता है — परिणामी फ़ाइल समतुल्य GeoJSON से 60–80% छोटी होती है। D3.js, Mapshaper और Observable का मानक इनपुट; इंटरैक्टिव कोरोप्लेथ मानचित्रों और वेब एटलसों के लिए आदर्श।
मुख्य विशेषताएँ
TopoJSON प्रारूप के बारे में
TopoJSON was invented by Mike Bostock, the author of D3.js, to solve a simple problem: in GeoJSON neighboring polygons store their shared border twice. TopoJSON moves all the lines into a common array of arcs that the objects then refer to. On top of that, coordinates are rounded to an integer grid and written as increments — the file gets sharply lighter.
The format is taken for web graphics and analytics: choropleths in D3, interactive atlases, boundary maps in Observable, lightweight layers for offline applications. The second motive is simplification: during generalization the shared borders move together, and no gaps appear between neighboring districts.
The output is a single document: every layer becomes a separate object inside it — roads, buildings, water and so on — and object attributes are preserved. Coordinates are in WGS84, up to 100,000 objects per layer. The topology is built by our own code, with no external dependencies.
The price of compactness is the rounding of coordinates. The grid step depends on the size of the area: for a district it is on the order of a meter, for a country hundreds of meters. For a web map that is invisible; for precise measurements take GeoJSON or GeoPackage.
TopoJSON फ़ाइलें कौन सा प्रोग्राम खोलता है
निम्नलिखित प्रोग्राम और अनुप्रयोग OSM2CDR से निर्यात की गई TopoJSON (Topology-Aware JSON) (.topojson) फ़ाइलों को खोल, संपादित और उनके साथ काम कर सकते हैं:
Format specifications
- Open standard
- 2D only
- Lossless (no quality loss)
- Stores feature attributes
- Output: 1 file
- TopoJSON (open spec). Topologically encoded GeoJSON: shared borders stored once, file size 30-80% smaller. Used by D3.js.
TopoJSON मानचित्रों का उपयोग कौन करता है
TopoJSON कैसे निर्यात करें
निर्यात के बाद कैसे खोलें
- D3.js — include topojson-client and unpack the layer you need: topojson.feature(topology, topology.objects.buildings), then the usual d3.geoPath.
- Mapshaper — drag the file onto mapshaper.org: objects and attributes are visible, and simplification and export to SHP or GeoJSON are right there.
- QGIS — opens .topojson as an ordinary vector layer through GDAL; handy for checking the geometry with your own eyes.
- Converting to GeoJSON — topo2geo buildings=buildings.geojson < map.topojson from the topojson-client package, or ogr2ogr.
- Leaflet and MapLibre — they do not understand the format directly: unpack it into GeoJSON on the client with the topojson-client library and feed it on as usual.
TopoJSON में लोकप्रिय मानचित्र
TopoJSON (Topology-Aware JSON) मानचित्र निर्यात प्राप्त करें
OpenStreetMap से पेशेवर TopoJSON मानचित्र डाउनलोड करें. तत्काल जनरेशन, कोई भी क्षेत्र.