Importing CAD files (DXF)

3DSC supports import of CAD vector files in DXF format, including georeferenced DXF files exported from desktop GIS or topographic suites. The DXF importer respects the project’s geographic shift values configured at scene level — meaning that an absolute-coordinate DXF will be correctly anchored to the local Blender origin defined by 3DSC (and, transitively, by the EM Tools Georeferencing panel when both add-ons are active).

See also

For the rationale behind coordinate shifting (why absolute-coordinate CAD data needs to be offset on import), see Coordinate shifting in 3DSC.

When to use this recipe

Reach for the DXF import flow when you have:

  • Topographic surveys (contour lines, breaklines) saved as DXF.

  • Architectural restitutions (plans, elevations) shared by colleagues in CAD.

  • Engineering or cadastral overlays that need to coexist with your photogrammetric meshes inside Blender.

For point clouds, photogrammetric meshes or textured assets, use the dedicated 3DSC importers (e.g. Import → 3DSC → Photogrammetric model). The DXF flow is intended for vector CAD content only.

Dependency: ezdxf

The 3DSC DXF importer reads the file with the ezdxf Python library. If it is not already in Blender’s Python, the importer reports an explicit error and points you to the DXF Import panel, which exposes a one-click installer. Install ezdxf once per Blender major version.

How the geographic shift is applied

The DXF importer reads three scene-level scalars set by 3DSC (scene.BL_x_shift, scene.BL_y_shift, scene.BL_z_shift) and subtracts them from the absolute DXF coordinates of each imported entity (LINE, CIRCLE, ARC, POLYLINE, HATCH, TEXT) before instantiating the Blender geometry. The result is that geometries land in the same local frame as the rest of your scene.

Worked example: if your DXF stores absolute Italian UTM coordinates (e.g. X = 312500.0) and your scene shift is BL_x_shift = 312000.0, the line will be created at Blender X = 500.0 — comfortable for the viewport and aligned with any photogrammetric model that was imported with the same shift.

Toggle the shift off (Shift Coordinates checkbox in the import dialog) when the DXF is already in local coordinates, or for sanity-check passes. See Coordinate shifting in 3DSC for the full rationale.

Step-by-step workflow

  1. Set the scene shift — either through the 3DSC import of any other georeferenced asset, through a SHIFT.txt file alongside your DXF, or by configuring the EM Tools Georeferencing panel (which writes the same BL_x/y/z_shift properties).

    See 3DSC4Metashape for the canonical SHIFT.txt format (EPSG::NNNN X Y Z).

  2. Open the DXF importer — File → Import → DXF (or the Import DXF button in the 3DSC sidebar). The dialog summarises the active shift values at the top, under Coordinate Settings.

  3. Choose which entity types to import — by default LINES, CIRCLES, ARCS, POLYLINES, HATCHES and TEXT are all enabled. Disable the ones you do not need to keep the scene clean (typical archaeological pass: LINES + POLYLINES + TEXT, ignoring hatches).

  4. Optional: merge by layer — when Merge by Layer is on, line segments belonging to the same CAD layer are stitched into polylines using a configurable distance tolerance (Merge Distance Tolerance, default 0.001 m). This dramatically reduces the number of Blender objects when importing dense CAD line work.

  5. Run the import — a new collection is created (named after the DXF file) and populated with curve and mesh objects, one per merged polyline / circle / arc / hatch / text. The operator reports the number of imported entities and the shift that was applied.

Coordinate system caveats

  • DXF without embedded CRS — DXF files do not carry a robust CRS declaration. The importer assumes the DXF coordinates are in the same CRS as the scene’s EPSG. If the source used a different CRS, the geometry will appear translated/rotated. Convert the DXF in a desktop GIS tool (or in CAD with a proper coordinate transform) before import.

  • DXF with a hidden offset — some CAD workflows apply a “false origin” to the DXF coordinates internally (e.g. subtract 7,000,000 m from Y to keep CAD precision). The 3DSC importer subtracts the scene shift, not any internal CAD shift; you may need to compose the two manually before import.

  • 3DSC and EM Tools share the same shift — when both add-ons are installed, edits in the EM Tools Georeferencing panel propagate to scene.BL_x/y/z_shift automatically, so the DXF importer sees a single, coherent reference. If only 3DSC is installed, set the shift through the 3DSC properties; the EM Tools panel is not required.

The georeferencing values configured for the scene are the single source of truth. If a DXF appears misaligned, audit the DXF’s CRS metadata first, then the scene’s shift values — in that order.