Orientation Strategies for Aerial Oblique Images

Abstract

ABSTRACT:Oblique aerial images become more and more distributed to fill the gap between vertical aerial images and mobile mapping systems. Different systems are on the market. For some applications, like texture mapping, precise orientation data are required. One point is the stable interior orientation, which can be achieved by stable camera systems, the other a precise exterior orientation. A sufficient exterior orientation can be achieved by a large effort in direct sensor orientation, whereas minor errors in the angles have a larger effect than in vertical imagery. The more appropriate approach is by determine the precise orientation parameters by photogrammetric methods using an adapted aerial triangulation. Due to the different points of view towards the object the traditional aerotriangulation matching tools fail, as they produce a bunch of blunders and require a lot of manual work to achieve a sufficient solution. In this paper some approaches are discussed and results are presented for the most promising approaches. We describe a single step approach with an aerotriangulation using all available images; a two step approach with an aerotriangulation only of the vertical images plus a mathematical transformation of the oblique images using the oblique cameras excentricity; and finally the extended functional model for a bundle block adjustment considering the mechanical connection between vertical and oblique images. Beside accuracy also other aspects like efficiency and required manual work have to be considered.

CHANGING THE PRODUCTION PIPELINE – USE OF OBLIQUE AERIAL CAMERAS FOR MAPPING PURPOSES

“…At scientific level, investigations have focused on the quality of the images, on acquisition geometry, on block triangulation accuracy and Dense Image Matching (DIM). Research topics include optimal viewing angles of the oblique sensor heads (in relation to surface characteristics), optimal overlaps between images and strips, tie point extraction approaches, and image orientation strategies, and have been reported in a number of publications (Jacobsen, 2008;Gerke and Nyaruhuma, 2009;Wiedemann and More, 2012;Rupnik et al, 2013;Rupnik et al, 2015). Given the increased number of oblique cameras on the market and the increased use of oblique imagery, software providers have updated the standard algorithms designed for vertical imagery, e.g.…”

OBLIQUE AERIAL IMAGERY FOR NMA – SOME BEST PRACTICES

“…First experiences with oblique imagery and automated aerial triangulation were presented in Jacobsen (2008) and Wiedemann, and Moré (2012). Yang et al (2012) proposed a multi-stage algorithm based on SIFT matching to improve automatic aerial triangulation results of oblique imagery.…”

Building Footprints Extraction from Oblique Imagery

“…Microsoft Bing) and just recently they have been used for metric purposes using semi-automated and automated solutions. Several papers dealing with oblique images' orientation have been already presented (Wiedemann and More, 2012;Gerke and Nyaruhuma, 2009) proposing the use of additional constraints within bundle adjustment (relative position between images, verticality of lines in the scene, etc. ), or simply aligning the (not adjusted) oblique cameras to the (adjusted) nadir ones with the use of known relative position between images (Wiedemann and More, 2012).…”

“…Several papers dealing with oblique images' orientation have been already presented (Wiedemann and More, 2012;Gerke and Nyaruhuma, 2009) proposing the use of additional constraints within bundle adjustment (relative position between images, verticality of lines in the scene, etc. ), or simply aligning the (not adjusted) oblique cameras to the (adjusted) nadir ones with the use of known relative position between images (Wiedemann and More, 2012). More recently other investigations have succeeded to automatically orient large image blocks with commercial (Fritsch et al, 2012) or open-source packages (Rupnik et al, 2013).…”