Survey Maps Module

The survey maps module handles the ingestion and processing of surveyor DWG files — the starting point for every Xylem project.

Processing Pipeline

Upload DWG
    │
    ▼
┌─────────────────────────────┐
│ 1. DWG → DXF Conversion    │  (ODAFileConverter or LibreDWG)
│    via xvfb-run (headless)  │
└─────────────┬───────────────┘
              │
              ▼
┌─────────────────────────────┐
│ 2. DXF → GeoJSON            │  (ogr2ogr from GDAL)
│    Extracts site boundary   │
└─────────────┬───────────────┘
              │
              ▼
┌─────────────────────────────┐
│ 3. AI Metadata Extraction   │  (Google Gemini)
│    - Site area              │
│    - Owner name             │
│    - Survey number          │
│    - Dimensions             │
└─────────────┬───────────────┘
              │
              ▼
┌─────────────────────────────┐
│ 4. Geocoding                │  (Google Maps API)
│    Address → lat/lon        │
└─────────────┬───────────────┘
              │
              ▼
┌─────────────────────────────┐
│ 5. Zone Analysis            │  (GDAL + GeoTIFF)
│    AAI Color Zone check     │
│    Authority detection      │
└─────────────┬───────────────┘
              │
              ▼
    SurveyMap record saved
    (with all file references)

Endpoints

Method	Path	Description
POST	/survey-maps/upload	Upload a DWG file
GET	/survey-maps/:id	Get survey map details and metadata
GET	/survey-maps/:id/geojson	Get the converted GeoJSON
GET	/survey-maps/:id/pdf	Get the converted PDF

Key Utilities

File	Purpose
dwgReader.ts	DWG → DXF/JSON conversion using LibreDWG CLI
dxfToGeojson.ts	DXF → GeoJSON conversion using ogr2ogr
geocodeAddress.ts	Google Geocoding API wrapper
getSiteElevation.ts	Open-Meteo elevation API
getAuthority.ts	Point-in-polygon authority detection using authorities.geojson
zoneChecker.ts	GDAL-based zone analysis using the AAI Color Zone Map GeoTIFF

Zone Analysis

The zone checker clips the AAI Color-Zone Map GeoTIFF to the site boundary and analyzes pixel colors to determine:

• Which color zone the site falls in (e.g., Yellow, Blue, Red)
• The corresponding height restrictions for that zone
• Uses gdalwarp for clipping and gdal2xyz.py for pixel extraction

Road Width Detection

For sites in Bangalore, the system checks the BDA CDP 2015 road network data (blr_roadWidth.geojson) to determine the abutting road width, which affects FAR and setback calculations.