The very high resolution of UAV-based images (better than 5cm ground resolution) opens new possibilities for mapping. The human operator can easily recognize most objects in the imagery. However, for an efficient workflow, ideally objects of interest should be detected and extracted automatically from the imagery: this expedites the surveying and mapping process. Although automatic image interpretation has a long history in research, the very high resolutions faced with nowadays brings new challenges: working on object basis rather than pixel, but at the same time exploit the pixel resolution for the retrieval of land tenure object features, modelling and exploitation of context in several hierarchy levels, and efficient use of prior knowledge. WP5 (Automate It) aims to exploit the imagery captured in the UAV flights of WP4 (Fly and Create) to enable automatic land tenure feature extraction. Such an approach cannot deliver complete matching – as some tenure boundaries are only social and not visible to sensors – however, even 50% matching would radically alter tenure mapping workflow costs and times.
In this work package, we introduce an open source approach that facilitates image-based cadastral mapping. We develop an automated cadastral boundary delineation approach applicable to UAV imagery. It is designed for areas, in which boundaries are demarcated by physical objects and are thus visible.
The tool’s workflow consists of (a) image segmentation, (b) boundary classification, and (c) interactive delineation:
All source code be found on GitHub. (c) is implemented in the BoundaryDelineation QGIS plugin. It can be downloaded via the QGIS plugin repository. All code is open source and can be used free of costs.
The following video demonstrates the use of the BoundaryDelineation QGIS plugin:
Feel free to share your ideas on the current state of the boundary delineation workflow. You can do this by evaluation the workflow in terms of its strengths, weaknesses, opportunities and threats (SWOT analysis) via the following form:
The survey is anonymous and aims to gather ideas and opinions for further development.