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Stephen Johnson

Publications and source records attributed to Stephen Johnson.

3 recordsLinked to original sources

Looks Can be Deceiving: Annotator and Reviewer Performance Across Imagery Sources in Crowd-Sourced Aerial Damage Assessment

This paper presents the first known empirical investigation of annotator and reviewer performance across multi-source remotely sensed imagery, evaluating human labeling across drone, crewed aviation, and satellite views. Because existing aerial imagery datasets rely predominantly on single-source imagery, there is no currently established state of practice for efficiently allocating human labor to curate large-scale, multi-source aerial datasets. This work addresses this limitation by analyzing annotator and reviewer performance within a post-disaster building damage assessment dataset of 9 disasters, where 20041 buildings in drone, 20695 buildings in crewed aviation, and 33392 buildings in satellite imagery were labeled. These labels, provided by 187 annotators, were then refined through two successive quality-control stages: a single-reviewer pass followed by a consensus-committee review. Our analysis reveals two findings that raise questions for standard crowd-sourcing practices. First, initial annotations were revised by the final committee at rates that rise steeply from higher- to lower-resolution sources (25.27% for crewed aviation and 36.95% for satellite), with the same ordering at every observed workflow stage. Second, a single individual review reduced but did not resolve this disagreement: after review, the committee still revised 6.85% of drone, 14.05% of crewed, and 20.86% of satellite labels. These observations suggest that, in workflows like this one, uniform review allocation leaves the most residual disagreement in lower-resolution imagery. Based on this evidence, and consistent with prior work on adaptive task assignment and budget-aware quality control, this paper offers three recommendations for multi-source dataset curation.

cs.CV

Dynamic Reliability: Reliably Sending Unreliable Data

5G and Beyond networks promise low-latency support for applications that need to deliver mission-critical data with strict deadlines. However, innovations on the physical and medium access layers are not sufficient. Additional considerations are needed to support applications under different network topologies, and while network setting and data paths change. Such support could be developed at the transport layer, ensuring end-to-end latency in a dynamic network and connectivity environment. In this paper, we present a partial reliability framework, which governs per-packet reliability through bespoke policies at the transport layer. The framework follows a no-ack and no-retransmit philosophy for unreliable transmission of packets, yet maintains cooperation with its reliable counterpart for arbitrary use of either transmission mode. This can then address latency and reliability fluctuations in a changing network environment, by smartly altering packet reliability. Our evaluations are conducted using mininet to simulate real-world network characteristics, while using a video streaming application as a real-time use-case. The results demonstrate the reduction of session packet volume and backlogged packets, with little to no effect on the freshness of the packet updates.

cs.NI

Rescattering of Vector Meson Daughters in High Energy Heavy Ion Collisions

We consider the role of hadronic rescattering of daughter kaons on the observed mass spectra from $ϕ$ meson decays in ultra-relativistic heavy ion collisions. A hadronic cascade code (RQMD v2.4) shows that $\sim$26% of all $ϕ$'s decaying to $K^+K^-$ in central Pb+Pb collisions at SPS energies ($E_{beam} = 158 GeV/A$) have a rescattered or absorbed daughter. This significantly affects the reconstructed invariant mass of the pair and shifts $ϕ$ mesons out of the mass peak. Kaon rescattering depletes the low velocity region, hardening and broadening the observed phi $m_t$ and rapidity distributions respectively, relative to the dilepton channel. This effect produces an apparent change in the experimentally determined branching ratio not necessarily related to chiral symmetry restoration. Comparisons to recent experimental measures at CERN energies reveal a possible mechanism to account for the shape of the observed spectra, though not their absolute relative magnitude.

nucl-th