Motivation

As if fallen out of time, the Steigerberg surf cliff rises from a disused gravel pit between the villages of Eckelsheim and Wendelsheim in the Rhineland-Palatinate district of Alzey-Worms. The cliff bears witness to a steep coast of the Lower Oligocene Sea that was formed about 30 million years ago and is unique in this form in Germany. Since the cliff is located on the property of the RKS Kies- und Splittwerke, it is to be filled in in the near future. The citizens’ initiative “Eckelsheimer Brandungskliff” therefore decided to have the Flonheim company Expofaktum recreate the cliff in original size and erect it not far from the original site. At the same time, i3mainz is to create a digital copy of the cliff as a textured 3D model.

Activities

The existing cliff has a base area of approx. 10m x 20m and a height extension of approx. 3m. Due to the jagged shape, 14 laser scanner positions were necessary to capture as many corners of the cliff as possible. These could be referenced via previously tachymetrically determined link points. Due to the shape of the cliff, there are many areas where no measurement with the laser scanner is possible. These areas were recorded using Structure from Motion (SfM) in several image composites, which were later processed into a 3D model. The areas captured with this method were also reframed using the tachymetrically determined intersection points.

The individual laser scan points were first registered in the post-processing to create a complete 3D model. The recorded image composites were processed into a 3D point cloud. These individual point clouds are used to fill the gaps in the laser scan point cloud. Since for these composites also tachymetrically measured targets are included, they can be transformed to the laserscan point cloud. The resulting complete 3D model of the reef was then meshed and textured using the image acquisition.

Results

In addition to terrestrial laser scanning (TLS), the i3mainz drone was used, which provided an overview point cloud of the entire cliff area as a result. The information obtained from the aerial photographs can be used for the 3D reconstruction. In addition, these images make it possible to texture the 3D data of the TLS. This gives the calculated 3D model the same colouring as the original surf cliff.

The results were handed over to the company Expofaktum in the form of a high-resolution, textured 3D model, which will be used in the future for interactive viewing of the surf reef. A full-scale 3D print of the surf reef is also to be created on this basis.