Module 12: CAD Manager (DXF Import & Export)

Use CAD Manager to import DXF drawings into a Mapplex project or export collected features as DXF files for engineering and drafting teams. Coordinate system selection is important: review the source CRS before importing and the target CRS before exporting.

---

1. Opening the CAD Manager

1. Navigate to the Data & Sync tab.
2. Tap the CAD Manager button (amber gradient with DXF badge).
3. The CAD Manager modal opens with two tabs: Import DXF and Export DXF.

Subscription: CAD Manager is a Pro feature. Free-tier users see a lock icon on the button — tapping it opens the upgrade screen.

---

2. Importing DXF Files

Step 1: Select the Source Coordinate System

Before loading a file, the CRS picker shows a single placeholder card: "Select a DXF file to detect CRS..."

After you load a DXF file (Step 2), the picker populates suggestions based on two sources:

Source	What It Provides
Coordinate Fingerprinting	Analyzes sample entities in your DXF to classify coordinates as WGS84, UTM, Web Mercator, local grid, or projected
Map Position	Uses your last known map center (current session or saved from a previous session) to infer the nearest UTM zone

The CRS picker organizes options into groups:

Group	Icon	Description
🎯 GPS Recommended	my_location	Best match based on your map position — marked with a "Best" badge
📡 Auto-Detected	auto_fix_high	CRS inferred from coordinate patterns in the DXF
📍 Nearby UTM Zones	near_me	Adjacent UTM zones in case the recommended zone is off by one
🌐 Common	public	Web Mercator (EPSG:3857) and other widely-used projections
✏️ Custom	edit	Enter a custom proj4 string for proprietary or legacy coordinate systems

Select a CRS card by tapping it. The selected card highlights in amber.

Tip: If no GPS position is available, a hint appears: "Open the Map tab first so Mapplex can suggest the correct UTM zone based on your location." Open the Map tab near the project area before importing so zone suggestions are more useful.

Step 2: Choose a DXF File

1. Tap the Choose DXF File button.
2. Select a .dxf file from your device.
3. The parser reads the file and displays:
   • CRS detection hint — e.g., "📐 Coordinates look like UTM (Easting/Northing in meters). Select the correct UTM zone above."
   • Projected coordinates badge — Shows easting/northing ranges when non-WGS84 coordinates are detected
   • Layer preview table — Lists every CAD layer with its entity types (LINE, CIRCLE, LWPOLYLINE, etc.) and entity count

Step 3: Import

1. Review the preview table. The import button shows the exact number of convertible entities.
2. Tap Import Convertible CAD Entities (N).
3. A progress bar appears showing import status:
   • Checking permissions...
   • Converting DXF to GeoJSON...
   • Importing layer 1/3 — "Roads LineString" — 247 features
   • Saving features...
   • Generating form fields...
   • Done! — 892 features imported

Cancelling an Import

If a large file is taking too long, tap the Cancel button next to the progress bar. The import stops at the next checkpoint — any layers already fully saved remain in your project.

What Happens After Import

• Each CAD layer becomes a separate Mapplex layer, split by geometry type (e.g., "Roads LineString", "Buildings Polygon")
• Form fields are auto-generated from the imported attributes
• The map view is automatically refreshed to show the new data
• You are navigated back to the Data tab to see the new layers

---

3. Exporting as DXF

Selecting What to Export

1. Switch to the Export DXF tab.
2. Choose a scope from the dropdown:
   • Entire Project — All features from all layers
   • Specific Layer — Only features from one layer

Generating the File

1. Select the target coordinate system for the exported DXF.
2. Tap Export as DXF.
3. The system converts your GeoJSON features to DXF format:
   • Points → DXF POINT entities
   • Lines → DXF POLYLINE entities
   • Polygons → DXF closed POLYLINE entities
   • Multi-geometries are expanded into individual entities
4. The .dxf file downloads automatically, named with the export date, for example mapplex_export_YYYY-MM-DD.dxf.

Export Coordinate Systems

CAD Manager can export DXF coordinates in several target CRS options:

Option	When to Use
WGS84 (EPSG:4326)	GPS longitude/latitude workflows or GIS systems that expect decimal degrees
Qatar National / Qatar 1974 grids	Qatar-based engineering or municipal workflows that require these projected systems
GPS-derived UTM	Field projects where the app can infer the likely UTM zone from the current map position
Custom proj4	Projects using a local grid, legacy survey system, or organization-specific projection

Confirm the receiving CAD team's expected CRS before sharing the export.

Compatibility

The exported DXF file is designed for common CAD/GIS tools that support DXF, including:

• AutoCAD
• Civil 3D
• BricsCAD
• QGIS
• MicroStation
• Any software supporting DXF R12/R14

Note: DXF files do not always carry enough CRS metadata for downstream software to infer the coordinate system. Include the selected CRS in your handoff notes when sending the file to a CAD or survey team.

---

4. Supported DXF Entities

Import (DXF → GeoJSON)

DXF Entity	Converts To	Notes
POINT	Point	Direct coordinate mapping
LINE	LineString	2-vertex line
LWPOLYLINE	LineString or Polygon	Closed polylines become Polygons
POLYLINE	LineString or Polygon	Handles 2D vertex-based polylines
CIRCLE	Polygon	Approximated with 64 segments
ARC	LineString	Approximated with segments
ELLIPSE	Polygon	Approximated with segments
SPLINE	LineString	Uses control/fit points
SOLID	Polygon	3/4-vertex filled regions
3DFACE	Polygon	3D triangular/quad faces
INSERT	—	Block references (not yet expanded)

Export (GeoJSON → DXF)

GeoJSON Type	DXF Entity	Notes
Point	POINT
MultiPoint	Multiple POINTs
LineString	POLYLINE
MultiLineString	Multiple POLYLINEs
Polygon	Closed POLYLINE	Outer ring only
MultiPolygon	Multiple closed POLYLINEs

---

5. Understanding Coordinate Systems

Most CAD drawings use local or projected coordinates rather than GPS coordinates. Here's how to identify and handle each type:

Coordinate Type	Typical Values	How to Identify	What to Select
WGS84 (GPS)	Lng: -180 to 180, Lat: -90 to 90	Small decimal values	"Do not reproject"
UTM	E: 100,000–900,000, N: 0–10,000,000	Large 6-7 digit easting values	The correct UTM zone (auto-suggested)
Web Mercator	X/Y: -20M to 20M	Very large values	Web Mercator (EPSG:3857)
Local Grid	X/Y: 0–10,000	Small metric values, no clear pattern	Custom proj4 string from your surveyor

Example: You receive a DXF from a civil engineer. The coordinates show easting values near 500,000 and northing values in the millions, which usually indicates UTM. If the map was last viewed near the project area, CAD Manager can suggest the likely UTM zone. Confirm the CRS with the CAD source when possible before importing.

---

6. Role-Based Access

Role	Import DXF	Export DXF
Owner	✅	✅
Admin	✅	✅
Editor	✅	✅
Collector	❌	✅
Viewer	❌	✅

Note: DXF import creates new project layers, which requires write access. All roles can export.

---

7. Tips for Best Results

• Ask your CAD source for the CRS — If the DXF uses a custom or country-specific projection, get the exact proj4 string from your surveyor or engineer.
• Open the Map tab before importing — Even briefly viewing the map saves your position, enabling automatic UTM zone suggestions.
• Review the preview table — Not all DXF entities convert to GeoJSON. The import button shows the exact count of convertible features.
• Split large DXF files — Files with 100,000+ entities may take longer. The progress bar and cancel button let you manage large imports.
• Check layer names after import — CAD layers with mixed geometry types are automatically split (e.g., "Survey Points" and "Survey LineString") to maintain valid Mapplex layer types.

---

Next: Proceed to Module 13: Engineering Drawing Export to learn how to export schematic drawing pages with your map PDF.