Direction arrows Wuppertal

The data set (status 02/2022) comprises 4775 directional arrows in the city area of Wuppertal, which have been detected as part of the NRW funding project “bergisch.smart_mobility” via a pattern recognition process automated with the ETL tool FME in the True Orthophoto of the City of Wuppertal (ground resolution 5 cm). The timeliness of the data set is thus determined by the date of the flight (27.03.2020) from which the aerial images for the calculation of the True Orthophoto originate. The data set is necessarily incomplete, as some direction arrows in the orthophoto are covered by motor vehicles and therefore cannot be identified by the pattern recognition process. The same applies to some directional arrows that are rendered unrecognizable by shadows. The lack of reliability can be gradually improved by evaluating orthophotos with other flight times and supplementing the additional directional arrows in the current data set. A statement of how quickly the completeness of this update strategy converges against 100 % is not yet possible. The update is scheduled to take place in the course of two years, during which the City of Wuppertal usually commissions aerial surveys of its urban area, i.e. for the first time in mid 2022. The pattern recognition and processing process developed in the above project is an efficient data collection process for the recording of directional arrows in connection with the construction of a digital traffic sign cadastre. In addition, the data set can be used to train algorithms from the field of artificial intelligence (AI) to detect directional arrows in aerial images. A transfer to other types of road markings is imaginable. The data set includes, on the one hand, a zip archive containing the georeferenced raster image sections (orthophoto snippets in the TIFF format with TIFF World File) in which directional arrows were detected, vector representations in point form (centrally positioned in the baseline of the travel direction arrows) and surface form (synthetic construction of the marking surface based on the standardised dimensions of the traffic arrows and transcribing rectangles corresponding to the orthophoto snippets). The dataset is available under an open data license (CC BY 4.0).