82 research outputs found
Detection of ice core particles via deep neural networks
Insoluble particles in ice cores record signatures of past climate parameters like vegetation, volcanic activity or aridity. Their analytical detection depends on intensive bench microscopy investigation and requires dedicated sample preparation steps. Both are laborious, require in-depth knowledge and often restrict sampling strategies. To help overcome these limitations, we present a framework based on Flow Imaging Microscopy coupled to a deep neural network for autonomous image classification of ice core particles. We train the network to classify 7 commonly found classes: mineral dust, felsic and basaltic volcanic ash (tephra), three species of pollen (Corylus avellana, Quercus robur, Quercus suber) and contamination particles that may be introduced onto the ice core surface during core handling operations. The trained network achieves 96.8 % classification accuracy at test time. We present the system’s potentials and limitations with respect to the detection of mineral dust, pollen grains and tephra shards, using both controlled materials and real ice core samples. The methodology requires little sample material, is non destructive, fully reproducible and does not require any sample preparation step. The presented framework can bolster research in the field, by cutting down processing time, supporting human-operated microscopy and further unlocking the paleoclimate potential of ice core records by providing the opportunity to identify an array of ice core particles. Suggestions for an improved system to be deployed within a continuous flow analysis workflow are also presented
Adaptively Transforming Graph Matching
Recently, many graph matching methods that incorporate pairwise constraint
and that can be formulated as a quadratic assignment problem (QAP) have been
proposed. Although these methods demonstrate promising results for the graph
matching problem, they have high complexity in space or time. In this paper, we
introduce an adaptively transforming graph matching (ATGM) method from the
perspective of functional representation. More precisely, under a
transformation formulation, we aim to match two graphs by minimizing the
discrepancy between the original graph and the transformed graph. With a linear
representation map of the transformation, the pairwise edge attributes of
graphs are explicitly represented by unary node attributes, which enables us to
reduce the space and time complexity significantly. Due to an efficient
Frank-Wolfe method-based optimization strategy, we can handle graphs with
hundreds and thousands of nodes within an acceptable amount of time. Meanwhile,
because transformation map can preserve graph structures, a domain
adaptation-based strategy is proposed to remove the outliers. The experimental
results demonstrate that our proposed method outperforms the state-of-the-art
graph matching algorithms
Detection of ice core particles via deep neural networks
Insoluble particles in ice cores record signatures of past climate parameters like vegetation dynamics, volcanic activity, and aridity. For some of them, the analytical detection relies on intensive bench microscopy investigation and requires dedicated sample preparation steps. Both are laborious, require in-depth knowledge, and often restrict sampling strategies. To help overcome these limitations, we present a framework based on flow imaging microscopy coupled to a deep neural network for autonomous image classification of ice core particles. We train the network to classify seven commonly found classes, namely mineral dust, felsic and mafic (basaltic) volcanic ash grains (tephra), three species of pollen (Corylus avellana, Quercus robur, Quercus suber), and contamination particles that may be introduced onto the ice core surface during core handling operations. The trained network achieves 96.8 % classification accuracy at test time. We present the system's potential and its limitations with respect to the detection of mineral dust, pollen grains, and tephra shards, using both controlled materials and real ice core samples. The methodology requires little sample material, is non-destructive, fully reproducible, and does not require any sample preparation procedures. The presented framework can bolster research in the field by cutting down processing time, supporting human-operated microscopy, and further unlocking the paleoclimate potential of ice core records by providing the opportunity to identify an array of ice core particles. Suggestions for an improved system to be deployed within a continuous flow analysis workflow are also presented
A Scale Independent Selection Process for 3D Object Recognition in Cluttered Scenes
During the last years a wide range of algorithms
and devices have been made available to easily acquire range
images. The increasing abundance of depth data boosts
the need for reliable and unsupervised analysis techniques,
spanning from part registration to automated segmentation.
In this context, we focus on the recognition of known objects
in cluttered and incomplete 3D scans. Locating and fitting a
model to a scene are very important tasks in many scenarios
such as industrial inspection, scene understanding, medical
imaging and even gaming. For this reason, these problems
have been addressed extensively in the literature. Several
of the proposed methods adopt local descriptor-based
approaches, while a number of hurdles still hinder the use
of global techniques. In this paper we offer a different
perspective on the topic: We adopt an evolutionary selection
algorithm that seeks global agreement among surface points,
while operating at a local level. The approach effectively
extends the scope of local descriptors by actively selecting
correspondences that satisfy global consistency constraints,
allowing us to attack a more challenging scenario where
model and scene have different, unknown scales. This leads
to a novel and very effective pipeline for 3D object recognition,
which is validated with an extensive set of experiment
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