Martin Vonheim Larsen

• Larsen, Martin Vonheim & Mathiassen, Kim (2024). Achieving Sub-Pixel Platform Accuracy With Pan-Tilt-Zoom Cameras in Uncertain Times. IEEE Transactions on Robotics. ISSN 1552-3098. doi: 10.1109/TRO.2024.3508141. Full text in Research Archive Show summary

  In this paper, we present a novel method for selfcalibrating a pan-tilt-zoom (PTZ) camera system model, specifically suited for long-range multi-target tracking with maneuvering low-cost PTZ cameras. Traditionally, such camera systems cannot provide accurate mappings from pixels to directions in the platform frame due to imprecise pan/tilt measurements or lacking synchronization between the pan/tilt unit and the video stream. Using a direction-only bundle adjustment (BA) incorporating pan/tilt measurements, we calibrate camera intrinsics, rolling shutter (RS) characteristics and pan/tilt mechanics, and obtain clock synchronization between the video stream and pan/tilt telemetry. We call the resulting method PTCEE (pan/tilt camera extrinsic and intrinsic estimation). In a thorough simulation study, we show that the proposed estimation scheme identifies model parameters with sub-pixel precision across a wide range of camera setups. Leveraging the map of landmarks from the BA, we propose a method for estimating camera orientation in real-time, and demonstrate pixel-level mapping precision on realworld data. Through the proposed calibration and orientation schemes, PTCEE enables high-precision target tracking during camera maneuvers in many low-cost systems, which was previously reserved for high-end systems with specialised hardware. Code is available at github.com/ffi-no/Paper-ptz-subpix-accuracy.

• Larsen, Martin Vonheim; Rolfsjord, Sigmund Johannes Ljosvoll; Gusland, Daniel; Ahlberg, Jörgen & Mathiassen, Kim (2024). BASE: Probably a Better Approach to Visual Multi-Object Tracking. VISIGRAPP. ISSN 2184-5921. doi: 10.5220/0012386600003660. Full text in Research Archive Show summary

  The field of visual object tracking is dominated by methods that combine simple tracking algorithms and ad hoc schemes. Probabilistic tracking algorithms, which are leading in other fields, are surprisingly absent from the leaderboards. We found that accounting for distance in target kinematics, exploiting detector confidence and modelling non-uniform clutter characteristics is critical for a probabilistic tracker to work in visual tracking. Previous probabilistic methods fail to address most or all these aspects, which we believe is why they fall so far behind current state-of-the-art (SOTA) methods (there are no probabilistic trackers in the MOT17 top 100). To rekindle progress among probabilistic approaches, we propose a set of pragmatic models addressing these challenges, and demonstrate how they can be incorporated into a probabilistic framework. We present BASE (Bayesian Approximation Single-hypothesis Estimator), a simple, performant and easily extendible visual tracker, achie (More)

• Larsen, Martin Vonheim; Haavardsholm, Trym Vegard & Mathiassen, Kim (2020). In-operation calibration of clock-bias and intrinsic parameters for pan-tilt-zoom cameras based on keypoint tracking. Proceedings of SPIE, the International Society for Optical Engineering. ISSN 0277-786X. doi: 10.1117/12.2573611. Full text in Research Archive Show summary

  We propose a method for jointly estimating intrinsic calibration and internal clock synchronisation for a pantilt- zoom (PTZ) camera using only data that can be acquired in the field during normal operation. Results show that this method is a promising starting point towards using software to replace costly timing hardware in such cameras. Through experiments we provide calibration and clock synchronisation for an off-the-shelf low-cost PTZ camera, and observe a greatly improved directional accuracy, even during mild manoeuvres.

• Haavardsholm, Trym Vegard; Smestad, Ragnar; Larsen, Martin Vonheim; Thoresen, Marius & Dyrdal, Idar (2016). Scene Understanding for Autonomous Steering, STO-MP-IST-127: Intelligence and Autonomy In Robotics. NATO Science and Technology Organization. ISSN 9789283720683. Full text in Research Archive

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• Bakstad, Lorns Harald; Baksaas, Magnus; Mygland, Katrine; Eikanger, Brage Gerdssønn; Gusland, Daniel & Hauge, Mariann [Show all 23 contributors for this article] (2025). LandX21 – teknologi i framtidas stridsfelt. Forsvarets forskningsinstitutt . Full text in Research Archive Show summary

  Etter suksessen med LandX i 2020 besluttet FFI å holde LandX som et årlig eksperiment. To uker hver høst skal forskere, brukere og industri samles på Rena for å eksperimentere med teknologi og nye løsninger for Forsvaret. Eksperimentukene avsluttes med en demonstrasjon for inviterte fra hele sektoren. Målet med demonstrasjonen er å formidle forskning til relevante brukere i Forsvaret og demonstrere hvordan ny teknologi kan bidra til å endre framtidas stridsfelt i landdomenet. I 2021 var temaet for LandX situasjonsforståelse, og forskningsprosjekter fra fem forskningsprogrammer ved FFI deltok. Eksperimenteringen dekket alt fra ubemannede og autonome systemer på bakken og i lufta til sensorfusjon, målfølging og robust og sikker kommunikasjon. I tillegg markerte LandX21 åpningen av FFIs nye innovasjonsarena, ICE worx Rena. I denne rapporten oppsummerer vi innholdet og resultatene fra eksperimentene helt overordnet og peker på relevante rapporter som kan utdype teknologien ytterligere. LandX21 var en suksess. Forskningsprogrammene rapporterte i ettertid at de hadde kommet lenger og lært mer enn de hadde gjort om de ikke hadde testet i felt. Tilbakemeldingene fra tilskuerne på demonstrasjonsdagen var at forskningsarbeidet hadde høy relevans, og at det ble formidlet på en god måte. LandX skal arrangeres igjen i 2022. Da skal vi utvide omfanget, og målsetningen er å samarbeide tettere med brukere for å få enda bedre kobling mellom forskningen og operativ bruk.

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