Abstract
Abstract. Many cities order spatial data systematically, in particular aerial nadir images and orthophotomaps. However, only the orthoimages and orthophotomaps are usually used by the city administration, particularly in spatial planning. Some of the users are not aware of the possibilities as to how the aerial images can be used. Spatial data users, who may not be specialists in photogrammetry, are sometimes not aware that it is possible to obtain 3D information from 2D images as a point cloud. The idea of dense image matching (DIM) is well-known and described in the field of photogrammetry. Although dense image matching is a time- and memory-consuming process, this does not present a major drawback with modern computing. Images for the test area – Warsaw – are characterised by Ground Sampling Distance (GSD) equal to 8 cm. These images can be successfully used in change detection processes, comparing the dense image matching point cloud from two different dates. What is important while considering land cover change detection, is that it is not necessary to generate a detailed and high-density point cloud, e.g. in order to detect changes in buildings. The main idea of the article is to present the possibility of using higher levels of images pyramid in dense image matching within the change detection process as a way to optimize the processing time and point cloud accuracy. Which level of pyramid is needed to detect different changes in urban land cover will also be discussed.
Highlights
Many cities and countries order aerial nadir images systematically, mostly to produce orthophotomaps
The point clouds generated from dense image matching (DIM) are mostly used for producing digital surface models (DSMs), which represents the elevation of the ground, as well all objects on the ground
The DSMs from at least two different dates can be successfully used in the change detection process by height comparison, and they can be generated from the aerial images, and from satellite stereopairs (Guerin et al, 2014)
Summary
Many cities and countries order aerial nadir images systematically, mostly to produce orthophotomaps. A number of factors can be identified that positively influence the application of the aerial image in terms of change detection These factors are: growing spatial resolution (GSD - Ground Sampling Distance), growing overlap and automation of the processes. The automation of DIM and DSM generation may lead to popularisation of using the data among national mapping agencies Some of them, such as the Ordnance Survey in Great Britain, implement some solutions in order to perform analyses and products which are useful from their point of view (Gladstone at al., 2012; Holland at al., 2012). The main idea of the article is to present the possibility of using higher levels of image pyramid in the DIM within the change detection process as a way to optimise the processing time and point cloud accuracy. Some problems concerning the comparison of two DSMs from different dates are described, as well as the possible way of solving this problem
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
