CommunicationPublished on 7 February 2025

swissSURFACE3D: Milestone achieved and course set for the future

With the release of data for the Canton of Bern, uniform and highly precise LiDAR data from swissSURFACE^3D is now available for all of Switzerland and the Principality of Liechtenstein. The nationwide survey, launched in spring 2017, was carried out in six stages and took a little more than seven years to complete. Due to high demand and positive experiences, swisstopo has initiated a new LiDAR survey to ensure the continued update of swissSURFACE^3D and swissSURFACE^3D Raster products.

LiDAR data of Thun Castle with Bälliz in the background — LiDAR pointcloud of Thun Castle with Bälliz in the background

What is a classified point cloud? Each point in the cloud has attributes in addition to its coordinates. One important attribute is the class membership. The first version of swissSURFACE^3D includes the following classification:
- Class 1: unclassified and temporary objects
- Class 2: ground
- Clas 3: vegetation
- Class 6: buildings
- Class 9: water
- Class 17: bridges, overpasses and viaducts
This attribute allows filtering by class or combination of classes, enabling various analytical and visualisation possibilities.The following images show point clouds colored by class, depicted as cross-sections and in three dimensions:
Other important attributes include the intensity of the reflected signal and the timestamp of the recording. The intensity provides insights into the texture, color, or material of the surface. The following illustration shows Cointrin airport, with points coloured by class and intensity. Although the entire runway, for example, is classified as class 2 (ground), the intensity values make it possible to distinguish the centerlines, the threshold, and tire marks on the runway. The timestamp allows for precise temporal identification of the recording time, which is crucial for difference calculations between two elevation models to analyze erosion, deposition, glacier melt, or mass movements.

Application examples of LiDAR data at swisstopo

swissALTI3D updates

swisstopo primarily uses LiDAR data to update existing terrain models. Both the point density and the precision of the measurements result in a significant improvement in quality. Additionally, the data now extends farther beyond the Swiss national borders, meaning that, for example, the Matterhorn is now fully covered by swissALTI^3D data. By 2025, the 50 cm raster cell resolution of swissALTI^3D will be fully based on high-resolution LiDAR data across Switzerland. Before-and-after comparisons using shaded relief clearly illustrate these improvements.

New surface model: swissSURFACE3D Raster

A digital surface model (DSM) differs from a digital terrain model in that it represents the terrain along with vegetation and artificial structures such as buildings or bridges. Using LiDAR data from swissSURFACE^3D, swisstopo can derive swissSURFACE^3D Raster. This is a current, high-resolution, and almost fully automated DSM that is released shortly after the LiDAR data collection.

Change Detection for swissTLM3D Production

A frequently used product from swisstopo is swissTLM^3D – the topographic landscape model of Switzerland. It includes both natural and artificial objects and represents them in three dimensions. The landscape is constantly changing, and all modifications must be detected and updated. Classified LiDAR data is also used for this purpose. Buildings or bridges, for example, can be extracted from the LiDAR point cloud based on their classification. These are then compared with the existing TLM dataset, and detected differences ultimately indicate possible changes.

Changes in the buildings on the left, bridges on the right. Green objects have not changed, red objects are missing from the TLM, blue objects are still present in the TLM but no longer in the LiDAR data set.

External Applications

Archaeology

In the fall of 2023, a volunteer detectorist discovered a striking terrain structure in the Colm la Runga area, about 900 meters above an ancient battlefield. He used the shaded relief of the digital terrain model swissALTI^3D, which is based on the high-resolution LiDAR data from swissSURFACE^3D, capable of detecting even the smallest elevation differences in the landscape. Since archaeological finds and sites (including those discovered through LiDAR) belong to the public, the volunteer, who collaborates with various cantonal archaeology offices, reported the discovery to the Archaeological Service of Graubünden. The striking terrain structure turned out to be an artificial fortification on a hilltop with multiple ditches and embankments. Initial findings and investigations indicate that it is indeed a 2,000-year-old Roman military camp. More details: Newly discovered Roman military camp in the Grisons.

Striking terrain structure Colm La Rugna — Drone imagery of the striking terrain structure at Colm La Rugna — © Fotografie Andrea Badrutt, Chur

Shaded relief of the striking terrain structure at Colm la Rugna

Colm La Rugna Site — Initial finds and investigations show that the site on the Colm la Rugna is a 2000-year-old Roman military camp — © Fotografie Andrea Badrutt, Chur

Artifact from Colm La Rugna — One of the artifacts — © Fotografie Andrea Badrutt, Chur

Landscape and Urban Planning

Researchers and architects from the Large Scale Virtualization and Modeling Lab at ETH Zurich use swissSURFACE^3D LiDAR point clouds as a foundation for a holistic approach to landscape and, in particular, urban design. The LiDAR data serves three key components:

Modeling terrain: Terrain models enable a better understanding of spatial structures and the development of site-specific solutions.
Scientific Visualization: Biophysical properties such as elevation differences, slope inclinations, or vegetation patterns can be derived, thereby supporting an analytical and design-oriented engagement with the landscape.
Computation of landscape physics: Terrain models derived from LiDAR data can, for example, be combined with climatic or hydrological data to simulate the effects of urban heat islands or impervious surfaces. Such simulations are essential for sustainable urban development.

The following video illustrates the three components using an example of an urban design for the Carouge municipality in the canton of Geneva.

Outlook

As part of the new campaign, the cantons of Appenzell Innerrhoden and Appenzell Ausserrhoden, Glarus, Schaffhausen, Schwyz, St. Gallen, Thurgau, Zug, and Zürich have already been surveyed. These data are currently being processed and will be continuously published in the coming months. And the work continues: LiDAR data is currently being continuously collected in the Romandie (blue block). By 2030, the data should be available nationwide.

Planning of swissSURFACE3D survey 2024 - 2029 — Planned acquisition stages of swissSURFACE3D. Approximately 12 months after the acquisition, the data will be publicly available

New Features

Considering customer feedback and LiDAR technology advancements, the next version of swissSURFACE^3D will include:

Higher point density: minimum 10 pulses per m².
Additional classes: facades, power poles, power lines, bridge pillars / supporting structures
Synthetic points on water bodies and under bridges
Normalized intensity values for cross-region comparisons
A new data format: cloud-optimized point cloud (.laz) instead of zipped .las files

LiDAR data from 2018 of Eglisau — Eglisau with its railway bridge over the Rhine. The LiDAR point cloud from 2018 is coloured by class. The bridge, power poles and overhead lines are all coloured grey because they belong to the same class. Facades and roofs are also assigned to the same class.

LiDAR data Eglisau 2024 — Eglisau with its railway bridge over the Rhine. The LiDAR point cloud 2024 is coloured according to new classes. Bridge, power poles, overhead lines and facades are coloured in different colours.

For questions or suggestions regarding measurement campaigns, swissSURFACE^3D, or geodata in general, feel free to contact geodata@swisstopo.ch. Stay updated through the geodata newsletter: Subscribe to Geodata Newsletter