Mark Hansen's Outputs (48)

Reinforcement learning for a perched landing in the presence of wind (2021)
Presentation / Conference Contribution

Previous research by the University of Bristol's Flight Lab demonstrated the feasibility of using reinforcement learning to generate a controller to perform an agile perched landing flight manoeuvre. However, flight testing demonstrated the limits of... Read More about Reinforcement learning for a perched landing in the presence of wind.

Image segmentation of underfloor scenes using a mask regions convolutional neural network with two-stage transfer learning (2020)
Journal Article

© 2020 Elsevier B.V. Enclosed spaces are common in built structures but pose a challenge to many forms of manual or robotic surveying and maintenance tasks. Part of this challenge is to train robot systems to understand their environment without huma... Read More about Image segmentation of underfloor scenes using a mask regions convolutional neural network with two-stage transfer learning.

Weed classification in grasslands using convolutional neural networks (2019)
Presentation / Conference Contribution

Automatic identification and selective spraying of weeds (such as dock) in grass can provide very significant long-term ecological and cost benefits. Although machine vision (with interface to suitable automation) provides an effective means of achie... Read More about Weed classification in grasslands using convolutional neural networks.

Surface normals based landmarking for 3D face recognition using photometric stereo captures (2019)
Presentation / Conference Contribution

In recent decades, many 3D data acquisition methods have been developed to provide accurate and cost-effective 3D captures of the human face. An example system, which can accommodate both research and commercial applications, is the Photoface device.... Read More about Surface normals based landmarking for 3D face recognition using photometric stereo captures.

Multispectral imaging for presymptomatic analysis of light leaf spot in oilseed rape (2019)
Journal Article

Background: The use of spectral imaging within the plant phenotyping and breeding community has been increasing due its utility as a non-invasive diagnostic tool. However, there is a lack of imaging systems targeted specifically at plant science duti... Read More about Multispectral imaging for presymptomatic analysis of light leaf spot in oilseed rape.

A photometric stereo-based 3D imaging system using computer vision and deep learning for tracking plant growth (2019)
Journal Article

© The Author(s) 2019. Published by Oxford University Press. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distri... Read More about A photometric stereo-based 3D imaging system using computer vision and deep learning for tracking plant growth.

Broad-leaf weed detection in pasture (2018)
Presentation / Conference Contribution

Weed control in pasture is a challenging problem that can be expensive and environmentally unfriendly. This paper proposes a novel method for recognition of broad-leaf weeds in pasture such that precision weed control can be achieved with reduced her... Read More about Broad-leaf weed detection in pasture.

Multispectral contactless 3D handprint acquisition for identification (2018)
Presentation / Conference Contribution

We present and experimentally demonstrate the potential effectiveness of a photometric stereo based high resolution system for capturing 3D handprints using visible light sources. The sub-surface vascular structures are also enhanced through the use... Read More about Multispectral contactless 3D handprint acquisition for identification.

Towards on-farm pig face recognition using convolutional neural networks (2018)
Journal Article

© 2018 Elsevier B.V. Identification of individual livestock such as pigs and cows has become a pressing issue in recent years as intensification practices continue to be adopted and precise objective measurements are required (e.g. weight). Current b... Read More about Towards on-farm pig face recognition using convolutional neural networks.

Innovative 3D and 2D machine vision methods for analysis of plants and crops in the field (2018)
Journal Article

© 2018 Elsevier B.V. Machine vision systems offer great potential for automating crop control, harvesting, fruit picking, and a range of other agricultural tasks. However, most of the reported research on machine vision in agriculture involves a 2D a... Read More about Innovative 3D and 2D machine vision methods for analysis of plants and crops in the field.

Photometric stereo for three-dimensional leaf venation extraction (2018)
Journal Article

© 2018 Elsevier B.V. Leaf venation extraction studies have been strongly discouraged by considerable challenges posed by venation architectures that are complex, diverse and subtle. Additionally, unpredictable local leaf curvatures, undesirable ambie... Read More about Photometric stereo for three-dimensional leaf venation extraction.

Automated monitoring of dairy cow body condition, mobility and weight using a single 3D video capture device (2018)
Journal Article

© 2018 Here we propose a low-cost automated system for the unobtrusive and continuous welfare monitoring of dairy cattle on the farm. We argue that effective and regular monitoring of multiple condition traits is not currently practicable and go on t... Read More about Automated monitoring of dairy cow body condition, mobility and weight using a single 3D video capture device.

Locomotion traits of dairy cows from overhead three-dimensional video (2016)
Presentation / Conference Contribution

We investigate two locomotion traits in dairy cows from overhead 3D video to observe lameness trends. Detecting lameness -particularly at an early stage- is important in order to allow early treatment which maximizes detection benefits. The proposed... Read More about Locomotion traits of dairy cows from overhead three-dimensional video.

Early and non-intrusive lameness detection in dairy cows using 3-dimensional video (2016)
Journal Article

© 2016 IAgrE Lameness is a major issue in dairy herds and its early and automated detection offers animal welfare benefits together with potentially high commercial savings for farmers. Current advancements in automated detection have not achieved a... Read More about Early and non-intrusive lameness detection in dairy cows using 3-dimensional video.

Overhead spine arch analysis of dairy cows from three-dimensional video (2016)
Presentation / Conference Contribution

We present a spine arch analysis method in dairy cows using overhead 3D video data. This method is aimed for early stage lameness detection. That is important in order to allow early treatment; and thus, reduce the animal suffering and minimize the h... Read More about Overhead spine arch analysis of dairy cows from three-dimensional video.

Quadruped locomotion analysis using three-dimensional video (2016)
Presentation / Conference Contribution

Abstract— To date, there has not been a single method
suitable for large-scale or regular-basis implementation to analyze the locomotion of quadruped animals. Existing methods are not sensitive enough for detecting minor deviations from healthy gait... Read More about Quadruped locomotion analysis using three-dimensional video.

Non-intrusive automated measurement of dairy cow body condition using 3D video (2015)
Presentation / Conference Contribution

Regular scoring of a dairy herd in terms of various physical metrics such as Body Condition Score (BCS), mobility and weight are essential for maintaining high animal welfare. This paper presents preliminary results of an automated system capable of... Read More about Non-intrusive automated measurement of dairy cow body condition using 3D video.

Long-range concealed object detection through active covert illumination (2015)
Presentation / Conference Contribution

© 2015 SPIE. When capturing a scene for surveillance, the addition of rich 3D data can dramatically improve the accuracy of object detection or face recognition. Traditional 3D techniques, such as geometric stereo, only provide a coarse grained recon... Read More about Long-range concealed object detection through active covert illumination.

BRDF estimation for faces from a sparse dataset using a neural network (2013)
Presentation / Conference Contribution

We present a novel �ve source near-infrared photometric
stereo 3D face capture device. The accuracy of the system is demonstrated by a comparison with ground truth from a commercial 3D scanner. We also use the data from the �ve captured images to mo... Read More about BRDF estimation for faces from a sparse dataset using a neural network.

Face recognition and verification using photometric stereo: The photoface database and a comprehensive evaluation (2013)
Journal Article

This paper presents a new database suitable for both 2-D and 3-D face recognition based on photometric stereo (PS): the Photoface database. The database was collected using a custom-made four-source PS device designed to enable data capture with mini... Read More about Face recognition and verification using photometric stereo: The photoface database and a comprehensive evaluation.