Potential research orientation (GEO5010) topics

Web-based CityJSON Extensions generator

CityJSON Extensions are a lesser known, lesser used part of the CityJSON specifications. This is partially due to the complexity of writing an Extension from scratch.

The goal of the assignment is to create a web-based CityJSON Extension generator that guides the user through the process. The extension generator would translate the user’s input into a valid CityJSON extension and provide useful information for each component. The user could provide input by filing out a dynamic form, or providing a sample CityJSON file, or something else entirely. The assignment begins by exploring relevant tools for JSON Schema generation, various options for user input and methods for verifying that the newly generated CityJSON Extension is a valid extension. The assignment can conclude with a written report of the findings, or continue with implementing a proof of concept.

Done in collaboration with Balázs Dukai at 3DGI.

Contact: Hugo Ledoux

Adding trees in City4CFD

City4CFD is an open-source tool that automatically reconstructs 3D city geometries tailored for microscale urban flow simulations. Its capabilities include reconstruction at multiple levels of detail, as well as including semantic surfaces, best practice guidelines set-up, and even multi-level geometry based on distance from point of interest.

This MSc thesis aims to add to City4CFD the automatic reconstruction of trees, this would facilitate their use within microclimate urban flow simulations with OpenFOAM. To start this topic, you would need to delve into the work from De Groot 2020, and explore how his approach to reconstruct trees at a different level of detail could be improved and implemented within City4CFD.

If you choose this topic, you can expect to learn about automatic geometry reconstruction and GIS data handling. To run CFD for testing can be optional. Programming experience and interest is an advantage for this topic. Your work will require the implementation of source code (in C++ preferably, but Python or others could be used).

Contact: Clara Garcia-Sanchez, Hugo Ledoux

Add CityJSON export to QGIS plugin

The current QGIS CityJSON plugin, developed by us, can only import CityJSON files to QGIS.

This project would add an export function to it, or at least explore how it could be done and start the work.

All coding is in Python.

Contact: Hugo Ledoux

Implement a cjio operator to de-triangulate CityJSON files

Files containing objects that are triangulated are often easier work with (the triangle is the primitive for visualisation, and the resulting geometries do not contain inner rings) but some use-cases are hindered by the amount of surfaces.

The aim of this project is simple: add an cjio operator that will de-triangulate (or un-triangulate?) a given CityJSON files, and allows us to store a new file where the same information is stored coplanar triangles are merged into polygons (potentially with inner rings).

Textures and materials (if any) also need to be handled.

If successful, the new operator would be added to cjio. All coding is in Python.

Contact: Hugo Ledoux

Add support for CityJSON in BlueSky

BlueSky is an open Air Traffic Simulator that is being actively used to perform research on Air Traffic Management and Air Traffic Flows. It would be extremely beneficial for such simulations to take advantage of 3D city models by adding support for CityJSON loading.

In this project you’ll have to implement parsing of CityJSON for the needs of BlueSky. The tool is open source and is written in Python. There will be support from the developers of the tool in the process.

You’ll improve your programming skills in the process and learn a lot about manipulating 3D geometry.

Contact: Stelios Vitalis

Automatic underpass height estimation from oblique images

For the 3DBAG project we are working on the addition of underpasses to the 3D building models. This assignment is about determining the correct height of building underpasses from oblique images. Ideally the approach should be automatic and robust so that we can scale it to the national level for the production of the 3DBAG dataset in the future.

Contact: Gina Stavropoulou and Jantien Stoter in collaboration with the company that maintains the 3DBAG with us 3DGI.