3,467 research outputs found
A Review of Landcover Classification with Very-High Resolution Remotely Sensed Optical Images—Analysis Unit, Model Scalability and Transferability
As an important application in remote sensing, landcover classification remains one of the most challenging tasks in very-high-resolution (VHR) image analysis. As the rapidly increasing number of Deep Learning (DL) based landcover methods and training strategies are claimed to be the state-of-the-art, the already fragmented technical landscape of landcover mapping methods has been further complicated. Although there exists a plethora of literature review work attempting to guide researchers in making an informed choice of landcover mapping methods, the articles either focus on the review of applications in a specific area or revolve around general deep learning models, which lack a systematic view of the ever advancing landcover mapping methods. In addition, issues related to training samples and model transferability have become more critical than ever in an era dominated by data-driven approaches, but these issues were addressed to a lesser extent in previous review articles regarding remote sensing classification. Therefore, in this paper, we present a systematic overview of existing methods by starting from learning methods and varying basic analysis units for landcover mapping tasks, to challenges and solutions on three aspects of scalability and transferability with a remote sensing classification focus including (1) sparsity and imbalance of data; (2) domain gaps across different geographical regions; and (3) multi-source and multi-view fusion. We discuss in detail each of these categorical methods and draw concluding remarks in these developments and recommend potential directions for the continued endeavor
A Review of Landcover Classification with Very-High Resolution Remotely Sensed Optical Images—Analysis Unit, Model Scalability and Transferability
As an important application in remote sensing, landcover classification remains one of the most challenging tasks in very-high-resolution (VHR) image analysis. As the rapidly increasing number of Deep Learning (DL) based landcover methods and training strategies are claimed to be the state-of-the-art, the already fragmented technical landscape of landcover mapping methods has been further complicated. Although there exists a plethora of literature review work attempting to guide researchers in making an informed choice of landcover mapping methods, the articles either focus on the review of applications in a specific area or revolve around general deep learning models, which lack a systematic view of the ever advancing landcover mapping methods. In addition, issues related to training samples and model transferability have become more critical than ever in an era dominated by data-driven approaches, but these issues were addressed to a lesser extent in previous review articles regarding remote sensing classification. Therefore, in this paper, we present a systematic overview of existing methods by starting from learning methods and varying basic analysis units for landcover mapping tasks, to challenges and solutions on three aspects of scalability and transferability with a remote sensing classification focus including (1) sparsity and imbalance of data; (2) domain gaps across different geographical regions; and (3) multi-source and multi-view fusion. We discuss in detail each of these categorical methods and draw concluding remarks in these developments and recommend potential directions for the continued endeavor
Gradient-free activation maximization for identifying effective stimuli
A fundamental question for understanding brain function is what types of
stimuli drive neurons to fire. In visual neuroscience, this question has also
been posted as characterizing the receptive field of a neuron. The search for
effective stimuli has traditionally been based on a combination of insights
from previous studies, intuition, and luck. Recently, the same question has
emerged in the study of units in convolutional neural networks (ConvNets), and
together with this question a family of solutions were developed that are
generally referred to as "feature visualization by activation maximization."
We sought to bring in tools and techniques developed for studying ConvNets to
the study of biological neural networks. However, one key difference that
impedes direct translation of tools is that gradients can be obtained from
ConvNets using backpropagation, but such gradients are not available from the
brain. To circumvent this problem, we developed a method for gradient-free
activation maximization by combining a generative neural network with a genetic
algorithm. We termed this method XDream (EXtending DeepDream with real-time
evolution for activation maximization), and we have shown that this method can
reliably create strong stimuli for neurons in the macaque visual cortex (Ponce
et al., 2019). In this paper, we describe extensive experiments characterizing
the XDream method by using ConvNet units as in silico models of neurons. We
show that XDream is applicable across network layers, architectures, and
training sets; examine design choices in the algorithm; and provide practical
guides for choosing hyperparameters in the algorithm. XDream is an efficient
algorithm for uncovering neuronal tuning preferences in black-box networks
using a vast and diverse stimulus space.Comment: 16 pages, 8 figures, 3 table
DISCO: Adversarial Defense with Local Implicit Functions
The problem of adversarial defenses for image classification, where the goal
is to robustify a classifier against adversarial examples, is considered.
Inspired by the hypothesis that these examples lie beyond the natural image
manifold, a novel aDversarIal defenSe with local impliCit functiOns (DISCO) is
proposed to remove adversarial perturbations by localized manifold projections.
DISCO consumes an adversarial image and a query pixel location and outputs a
clean RGB value at the location. It is implemented with an encoder and a local
implicit module, where the former produces per-pixel deep features and the
latter uses the features in the neighborhood of query pixel for predicting the
clean RGB value. Extensive experiments demonstrate that both DISCO and its
cascade version outperform prior defenses, regardless of whether the defense is
known to the attacker. DISCO is also shown to be data and parameter efficient
and to mount defenses that transfers across datasets, classifiers and attacks.Comment: Accepted to Neurips 202
Towards Monitoring Parkinson's Disease Following Drug Treatment: CGP Classification of rs-MRI Data
Background and Objective: It is commonly accepted that accurate monitoring of
neurodegenerative diseases is crucial for effective disease management and
delivery of medication and treatment. This research develops automatic clinical
monitoring techniques for PD, following treatment, using the novel application
of EAs. Specifically, the research question addressed was: Can accurate
monitoring of PD be achieved using EAs on rs-fMRI data for patients prescribed
Modafinil (typically prescribed for PD patients to relieve physical fatigue)?
Methods: This research develops novel clinical monitoring tools using data from
a controlled experiment where participants were administered Modafinil versus
placebo, examining the novel application of EAs to both map and predict the
functional connectivity in participants using rs-fMRI data. Specifically, CGP
was used to classify DCM analysis and timeseries data. Results were validated
with two other commonly used classification methods (ANN and SVM) and via
k-fold cross-validation. Results: Findings revealed a maximum accuracy of
74.57% for CGP. Furthermore, CGP provided comparable performance accuracy
relative to ANN and SVM. Nevertheless, EAs enable us to decode the classifier,
in terms of understanding the data inputs that are used, more easily than in
ANN and SVM. Conclusions: These findings underscore the applicability of both
DCM analyses for classification and CGP as a novel classification technique for
brain imaging data with medical implications for medication monitoring.
Furthermore, classification of fMRI data for research typically involves
statistical modelling techniques being often hypothesis driven, whereas EAs use
data-driven explanatory modelling methods resulting in numerous benefits. DCM
analysis is novel for classification and advantageous as it provides
information on the causal links between different brain regions.Comment: arXiv admin note: substantial text overlap with arXiv:1910.0537
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