Import a terrain model (DGM)

What is imported

A height raster is processed into a Toposolid (Revit 3D terrain). The Toposolid can be used for terrain visualization, height studies, sectional cuts, and as a base for terrain-bound concrete or path-construction models.

Accepted source formats

• GeoTIFF DEM (.tif, .tiff) — the official standard. Single-channel 16- or 32-bit elevation values per pixel. Both strip- and tile-organised GeoTIFFs are read (e.g. Lower Saxony 512×512 tiles or Cloud-Optimized GeoTIFF).
• XYZ point file (.xyz, .txt) — ASCII file with three numeric columns per row. Separators are auto-detected (space, tab, semicolon). (XYZ point lists are not available in the Free edition — use a GeoTIFF instead.)

Common raster spacings in Germany: DGM1 (1 m), DGM5 (5 m), DGM10 (10 m), up to DGM50 (50 m).

Anatomy of a geoportal file

AdV-conformant filenames follow this pattern:

dgm{spacing in m}_{UTM zone}_{East-LL in km}_{North-LL in km}_{tile size in km}_{state}_{capture year}.tif

Example:

dgm1_32_662_5650_1_th_2020-2025.tif
└──┘└┘ └─┘ └──┘ └┘ └┘ └───────┘
DGM1  Z32 East North 1km TH Capture
                          (Thuringia)

Companion files per tile:

• .tif — GeoTIFF with elevation raster (or .xyz as alternative without CRS header)
• .meta — AdV metadata as plain text (data origin, accuracy, capture date), not parsed

GeoBridge reads from the GeoTIFF: the coordinate reference system (GeoKey tag or accompanying .prj), the cell size (pixel size in world metres), the PixelIsPoint/PixelIsArea convention, and the elevation value per pixel including the no-data marker (NaN).

Workflow

1. Preparation — download a DGM tile from the geoportal.
2. Click "DGM" in the ribbon.
3. Select file — file picker filtered to the accepted formats.
4. Georeferencing dialog — see Before the first import. On the first import the Survey Point is set; on later imports it is adopted.
5. Polygon filter (optional) — see Define polygon filter. Default "No polygon" imports the entire tile. With a polygon, only points inside the polygon area are used.
6. Choose preparation — Smoothing and Resolution; see next section.
7. Result — Toposolid is created; the TaskDialog reports vertices, triangles, and source file.

Preparation — Smoothing and Resolution

The dialog Terrain — Preparation has two independent axes, each with a live estimate of the resulting triangle count per option:

Smoothing — how calm does the terrain look?

Elevation data contains small measurement noise (typically ±10 cm), which shows up in the Toposolid as "wobbly" triangles. Smoothing averages each height value with its neighbours — terrain becomes softer, small details blur. The point count stays the same; only the Z values are smoothed.

Resolution — how many triangles in the model?

Determines how many of the raw points are passed to the Toposolid — i.e. how fine the triangles become. More triangles = more detail, but Revit reacts slower (especially when rotating large tiles). Resolution acts as stride decimation: every N-th point is kept.

The chosen settings are persisted in the ImportRecord and can be reopened from the Mesh quality… ribbon button — geometry is rebuilt with the new values without re-reading the source file.

In the Free edition the preparation choice is not asked; Light + Standard is fixed.

Import multiple tiles (Pro)

Pro accepts a multi-selection in the file dialog and builds all selected tiles in one run. Pro additionally computes an edge-merge along shared tile boundaries: identical elevation values along common edges are stitched so the finished terrain has no visible seam between tiles. Free imports one tile per click; multiple tiles appear side-by-side without edge-merge.

DOP as material on Toposolid (Pro)

After the preparation step in the DGM wizard, the DOP as material on Toposolid dialog appears whenever at least one previously imported orthophoto exists in the project. Choices:

• No material — the Toposolid keeps the current default material of the chosen Toposolid type (default).
• Use DOP from project — multi-select picker of the existing DOPs. The chosen orthophotos are mapped as textures onto the Toposolid's top face.

When multiple DOPs are selected (multi-pick), they are combined into one composite image and applied as a single material — useful when the terrain spans several DOP tiles. Project North angle and each DOP's SW corner are used per-DOP for the texture alignment, so the composite is placed correctly on rotated projects.

Note: the composite image is stored in the project folder. When the project is moved or copied, take the image folder with it.

Overlap with an existing DGM Toposolid

If a new DGM import spatially overlaps a DGM Toposolid already present in the project, GeoBridge asks before attempting the import:

• Import anyway — edge merge is disabled for this import (overlapping Toposolids do not coexist), auto-fallback engages if Revit rejects the build with InternalException.
• Cancel — delete the existing Toposolid first — safe path. Delete the existing Toposolid in Revit and retry the import.

The default button is "Cancel" because Revit frequently rejects overlapping Toposolids with an opaque exception, and delete-then-retry is the more robust path.

Detection only fires on real overlap of the tile bounding boxes. Tiles directly adjacent (shared edge, no area) do not trigger the dialog.

Concave polygons

A concave clip polygon (with a notch) reliably removes all points outside. Revit's own Toposolid triangulation, however, bridges the notch and produces a convex-hull-like outer outline. Workaround: split the concave polygon into two or more convex sub-pieces and run a separate DGM import per piece.

Pro vs. Free for DGM

Notes

• "Shape changed" warning — this Revit warning may appear when building the Toposolid and is harmless. GeoBridge suppresses it where possible; if it surfaces anyway, it can be closed.
• PixelIsPoint vs PixelIsArea — some GeoTIFF DGMs are written as pixel-as-point (cell centre on the coordinate), others as pixel-as-area (coordinate is the cell corner). GeoBridge auto-detects both; if a discrepancy with another data source appears, compare visually in the site plan.
• Very fine rasters — DGM1 (1 m) over large tiles quickly produces millions of raw points. Resolution "Standard" or pre-clipping in QGIS is recommended for these cases.