In 2020, the city of Groningen has stated the objective of having a 3D digital copy of its city developed. For a number of years, the city has been trying to take 3D as the standard for its products and following this, a 3D model of the city would help to implement spatial plans faster, more cost-efficiently and more transparently.
The city of Groningen set high standards for accuracy for their end products. Within the consortium of parties in this project, a collection with high overlap was chosen 80/80% for the center and 80/60% for the other districts. A GSD of 2.5 cm was chosen for the center and 5 cm for the other districts. We have the LiDAR, Nadir & Obliek images in one flight.
The multiple collection also ensures multiple use of the data. The nadir images have been processed into True-Orthofoto which is used as a pad for the model. The True-Ortho is placed over the terrain model which has been reworked from the LiDAR point cloud. The nadir images have also been processed into stereo photos which have been used for the modeling. Aerotriangulation has been carried out on the oblural images, an important element for texturing the buildings. The obligatory images can also be consulted in a viewer.
The assignment was accepted and executed in combination with Future Insight and Avineon. This consortium operates on a frequent basis from the initiative of the Netherlands in 3D! Read more about the Netherlands in 3D on www.nederlandin3d.nl.
The city Groningen has found the collaboration with Kavel 10 and more broadly the consortium very pleasant. Where it can be a challenge in a customer-supplier relationship to find a suitable form of cooperation and to delineate expectations back and forth, this went perfectly from day one. The 3D model of Groningen has opened eyes in our organization. Broader than the Spatial Domain, people are impressed by the quality and possibilities. Now that we have a detailed virtual representation of our city and surrounding area, we have the basics in order and we can realize benefits. That is definitely thanks to Kavel 10!
For the 3D digital copy of the city, we used several collection techniques. The different datasets were collected simultaneously from the aircraft. This ensures that the data can be combined well and is therefore perfect for processing 3D models. Due to the high overlap and low flight heights, it has become an extensive dataset.
LIDAR (Laser Imaging Detection And Ranging) is a technology that determines the distance to an object or surface through the use of laser pulses. The special thing about this technique is that it makes it possible to eliminate the vegetation and vegetation present from the measurements and to measure the actual ground level. We used the LiDAR data to create an up-to-date and accurate terrain model and to model the trees and bridges.
With our metric camera, images are shot simultaneously with 5 lenses. These lenses are both downwards (Nadir) and in 4 wind directions (oblique). The flight planning is planned in such a way that all images with overlap are taken. The collection of these images is used multiple times. For generating a True-Orthophoto, Stereo photos for modeling, Obliek images to texture the buildings and to consult in a viewer.
Prior to the collection, our surveyor measured soil control points spread over the project area. After the collection, we can fit the data at these points with which we can fit the collected data into the Dutch coordinate system.
The term LOD (Level of Detail) model refers to the detail level of the model. In this context we mean object-oriented 3D models. These models are built on the basis of our collected data and enriched with attribute data. This data is linked to the 3D geometry and thus enriched with existing data. The detail level of the model can be coordinated in consultation with the customer. Deliveries of LOD models are often made in line with established guidelines in CityGML.
All processed and modelled products are published in an online environment, in this viewer there are various tools that can be used by the county of Groningen for planning, environmental management and ultimately a more efficient way of working for urban development.
