Leaflet: How To Display A Geojson File With AutoCAD Data?

I am tried to display geojson file (converted from AutoCAD file to geojson) as the Second layer (first layer maps OSM). But geojson content occupies entire maps, not in a specific

Solution 1:

TL;DR: You're confusing the coordinate systems.

---

Coordinates in GeoJSON data refer to degrees of longitude in the X axis, and degrees of longitude in the Y axis. This is by definition. When these coordinates are mapped onto a cartesian plane, that becomes an equirectangular projection.

By contrast, coordinates in AutoCAD (or pretty much any other CAD software) usually refer to meters (or imperial feet) when there's an architect between the chair and the keyboard; also they usually refer to millimeters/centimeters (or tenths of an imperial inch) when there's a mechanical engineer between chair and keyboard.

So a line from -53, -10 to 0, 40 can be either a flight from Brazil to Spain, a 72-meter-long wall, or a 72mm length of cable.

Since you are using GeoJSON, and GeoJSON only cares about geographical coordinates in degrees of latitude/longitude, any software will assume that your coordinates are degrees of lat/long, and display them accordingly. The default for Leaflet is to project the data onto Web Mercator, and clip anything above/below +90/-90 degrees of latitude. This is to be expected.

---

So, the coordinate systems are wrong, what to do now? I see two approaches:

1. Change the CAD coordinates so they refer to lat-lng. This process is known as georeferencing. The specifics differ and can be complicated, so searching through GIS StackExchange might be a good start.

2. Tell Leaflet to display non-geographical coordinates. Read the Leaflet tutorial on the topic, and use the crs: L.CRS.Simple option when instantiating your map. That should make your data display (more) correctly, but remember that GeoJSON is not an appropriate data format for non-geographical data.

In any case, be aware of your coordinate system.

Solution 2:

Finally i got solution by unprojecting CRS EPSG3857 then the same geojson file working fine in leaflet.Thanks..

By adding,

L.CRS.EPSG3857.unproject(point) // where point is coords.