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This contribution presents concepts and methods to estimate the quality of facade textures taken from a set of overlapping aerial images. It aims at providing a key component for a workflow to derive appearance elements such as facade textures for large-scale virtual 3D city models in an automated way. We describe a technique to project aerial imagery generated by the High Resolution Stereo Camera (HRSC) onto the 3D geometry of a virtual city model. This technique can be applied in real-time using 3D graphics hardware. It is based on rectified images that are extracted for each facade at a fixed spatial resolution along with a quality map encoding the actual effective spatial resolution of the projected aerial image. We demonstrate the potential of this combination of facade images and quality maps for applications such as facade coverage determination.

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Single Sign-On (SSO) is becoming an increasingly popular authentication method for users that leverages a trusted Identity Provider (IdP) to bootstrap secure authentication tokens from a single user password. It alleviates some of the worst security issues of passwords, as users no longer need to memorize individual passwords for all service providers, and it removes the burden of these service to properly protect huge password databases. However, SSO also introduces a single point of failure. If compromised, the IdP can impersonate all users and learn their master passwords. To remedy this risk while preserving the advantages of SSO, Agrawal et al. (CCS'18) recently proposed a distributed realization termed PASTA (password-authenticated threshold authentication) which splits the role of the IdP across n servers. While PASTA is a great step forward and guarantees security as long as not all servers are corrupted, it uses a rather inflexible corruption model: servers cannot be corrupted adaptively and --- even worse --- cannot recover from corruption. The latter is known as proactive security and allows servers to re-share their keys, thereby rendering all previously compromised information useless. In this work, we improve upon the work of PASTA and propose a distributed SSO protocol with proactive and adaptive security (PESTO), guaranteeing security as long as not all servers are compromised at the same time. We prove our scheme secure in the UC framework which is known to provide the best security guarantees for password-based primitives. The core of our protocol are two new primitives we introduce: partially-oblivious distributed PRFs and a class of distributed signature schemes. Both allow for non-interactive refreshs of the secret key material and tolerate adaptive corruptions. We give secure instantiations based on the gap one-more BDH and RSA assumption respectively, leading to a highly efficient 2-round PESTO protocol. We also present an implementation and benchmark of our scheme in Java, realizing OAuth-compatible bearer tokens for SSO, demonstrating the viability of our approach.

This paper is concerned with concepts and techniques that support the automated generation of facade textures. In contrast to terrain textures, which can be derived automatically, capturing and processing facade textures still represent costly and time intensive tasks. In this paper we introduce a number of basic tools that allow us to work with aerial imagery captured by the High Resolution Stereo Camera (HRSC). In addition to the nadir view of standard aerial photography an HRSC image set contains multiple tilted views, in which facades are depicted more prominently. We develop a camera model for OpenGL that approximates the unique imaging sensor used for HRSC. With our tools, we can visually explore original HRSC imagery and synthesize idealized HRSC imagery based on virtual 3D city models. The visual exploration of HRSC images allows us to select regions from real-world images that have special properties useful for algorithm development, whereas the synthesis is used to generate test data and to run simulations.