A 2D coordinate is an ordered pair (x, y) that locates a point in a specified reference system. On a floor plan, positions are measured relative to a chosen origin (0, 0). The numbers alone do not establish where the point lies on a real-world map. section 2.5.2
Coordinates make spatial data usable. Sensor positions recorded on a floor plan can be compared with other local positions to find nearby assets, or transformed into global coordinates to place readings on a geolocated model. section 4.1.4 section 7.3.2
To place a local 2D point on a projected map:
- Identify the local origin, the corresponding map position, and any rotation between site north and true north. section 2.5.2
- Rotate the point, then translate it by the map coordinates of the origin. A 3 × 3 transformation matrix combines these operations. section 2.5.2
- Choose a target reference system suited to the area and measurements. A further conversion may be needed when another system expects a different one. section 2.5.2
Find a nearby sensor
Given local positions (0.1, 3) and (0.839, 0.5), calculate their 2D Euclidean distance. The rear garden tap is about 2.6 metres from the first position, so a search with a 5-metre radius includes it. This uses one local coordinate space; it does not require map coordinates. section 4.1.4
Listing 2.8 Using PyProj to simplify transforming UTM coordinates to WGS84
from pyproj import Transformer transformer = Transformer.from_crs( "EPSG:32736", "EPSG:4326", always_xy=True) easting, northing = 471519, 7977628 lon, lat = transformer.transform(easting, northing) print(lon, lat)
The PyProj listing converts a UTM easting and northing in EPSG:32736 to WGS84 longitude and latitude in EPSG:4326. section 2.5.2
A position is not an asset identity. Global coordinates can anchor sensor readings in a 3D scene, but associating those readings with a particular model element may still require matching identifiers or reconciling inconsistent metadata. Where height matters, a 2D position may also need a z-axis. section 7.3.2 section 4.1.4
