21 research outputs found
Cross-Paced Representation Learning with Partial Curricula for Sketch-based Image Retrieval
In this paper we address the problem of learning robust cross-domain
representations for sketch-based image retrieval (SBIR). While most SBIR
approaches focus on extracting low- and mid-level descriptors for direct
feature matching, recent works have shown the benefit of learning coupled
feature representations to describe data from two related sources. However,
cross-domain representation learning methods are typically cast into non-convex
minimization problems that are difficult to optimize, leading to unsatisfactory
performance. Inspired by self-paced learning, a learning methodology designed
to overcome convergence issues related to local optima by exploiting the
samples in a meaningful order (i.e. easy to hard), we introduce the cross-paced
partial curriculum learning (CPPCL) framework. Compared with existing
self-paced learning methods which only consider a single modality and cannot
deal with prior knowledge, CPPCL is specifically designed to assess the
learning pace by jointly handling data from dual sources and modality-specific
prior information provided in the form of partial curricula. Additionally,
thanks to the learned dictionaries, we demonstrate that the proposed CPPCL
embeds robust coupled representations for SBIR. Our approach is extensively
evaluated on four publicly available datasets (i.e. CUFS, Flickr15K, QueenMary
SBIR and TU-Berlin Extension datasets), showing superior performance over
competing SBIR methods
Deep Shape Matching
We cast shape matching as metric learning with convolutional networks. We
break the end-to-end process of image representation into two parts. Firstly,
well established efficient methods are chosen to turn the images into edge
maps. Secondly, the network is trained with edge maps of landmark images, which
are automatically obtained by a structure-from-motion pipeline. The learned
representation is evaluated on a range of different tasks, providing
improvements on challenging cases of domain generalization, generic
sketch-based image retrieval or its fine-grained counterpart. In contrast to
other methods that learn a different model per task, object category, or
domain, we use the same network throughout all our experiments, achieving
state-of-the-art results in multiple benchmarks.Comment: ECCV 201
Sketch-based 3D Shape Retrieval using Convolutional Neural Networks
Retrieving 3D models from 2D human sketches has received considerable
attention in the areas of graphics, image retrieval, and computer vision.
Almost always in state of the art approaches a large amount of "best views" are
computed for 3D models, with the hope that the query sketch matches one of
these 2D projections of 3D models using predefined features.
We argue that this two stage approach (view selection -- matching) is
pragmatic but also problematic because the "best views" are subjective and
ambiguous, which makes the matching inputs obscure. This imprecise nature of
matching further makes it challenging to choose features manually. Instead of
relying on the elusive concept of "best views" and the hand-crafted features,
we propose to define our views using a minimalism approach and learn features
for both sketches and views. Specifically, we drastically reduce the number of
views to only two predefined directions for the whole dataset. Then, we learn
two Siamese Convolutional Neural Networks (CNNs), one for the views and one for
the sketches. The loss function is defined on the within-domain as well as the
cross-domain similarities. Our experiments on three benchmark datasets
demonstrate that our method is significantly better than state of the art
approaches, and outperforms them in all conventional metrics.Comment: CVPR 201
A Novel Medical Freehand Sketch 3D Model Retrieval Method by Dimensionality Reduction and Feature Vector Transformation
To assist physicians to quickly find the required 3D model from the mass medical model, we propose a novel retrieval method, called DRFVT, which combines the characteristics of dimensionality reduction (DR) and feature vector transformation (FVT) method. The DR method reduces the dimensionality of feature vector; only the top M low frequency Discrete Fourier Transform coefficients are retained. The FVT method does the transformation of the original feature vector and generates a new feature vector to solve the problem of noise sensitivity. The experiment results demonstrate that the DRFVT method achieves more effective and efficient retrieval results than other proposed methods
Doodle to Search: Practical Zero-Shot Sketch-based Image Retrieval
In this paper, we investigate the problem of zero-shot sketch-based image
retrieval (ZS-SBIR), where human sketches are used as queries to conduct
retrieval of photos from unseen categories. We importantly advance prior arts
by proposing a novel ZS-SBIR scenario that represents a firm step forward in
its practical application. The new setting uniquely recognizes two important
yet often neglected challenges of practical ZS-SBIR, (i) the large domain gap
between amateur sketch and photo, and (ii) the necessity for moving towards
large-scale retrieval. We first contribute to the community a novel ZS-SBIR
dataset, QuickDraw-Extended, that consists of 330,000 sketches and 204,000
photos spanning across 110 categories. Highly abstract amateur human sketches
are purposefully sourced to maximize the domain gap, instead of ones included
in existing datasets that can often be semi-photorealistic. We then formulate a
ZS-SBIR framework to jointly model sketches and photos into a common embedding
space. A novel strategy to mine the mutual information among domains is
specifically engineered to alleviate the domain gap. External semantic
knowledge is further embedded to aid semantic transfer. We show that, rather
surprisingly, retrieval performance significantly outperforms that of
state-of-the-art on existing datasets that can already be achieved using a
reduced version of our model. We further demonstrate the superior performance
of our full model by comparing with a number of alternatives on the newly
proposed dataset. The new dataset, plus all training and testing code of our
model, will be publicly released to facilitate future researchComment: Oral paper in CVPR 201
Cross-Modal Hierarchical Modelling for Fine-Grained Sketch Based Image Retrieval
Sketch as an image search query is an ideal alternative to text in capturing
the fine-grained visual details. Prior successes on fine-grained sketch-based
image retrieval (FG-SBIR) have demonstrated the importance of tackling the
unique traits of sketches as opposed to photos, e.g., temporal vs. static,
strokes vs. pixels, and abstract vs. pixel-perfect. In this paper, we study a
further trait of sketches that has been overlooked to date, that is, they are
hierarchical in terms of the levels of detail -- a person typically sketches up
to various extents of detail to depict an object. This hierarchical structure
is often visually distinct. In this paper, we design a novel network that is
capable of cultivating sketch-specific hierarchies and exploiting them to match
sketch with photo at corresponding hierarchical levels. In particular, features
from a sketch and a photo are enriched using cross-modal co-attention, coupled
with hierarchical node fusion at every level to form a better embedding space
to conduct retrieval. Experiments on common benchmarks show our method to
outperform state-of-the-arts by a significant margin.Comment: Accepted for ORAL presentation in BMVC 202
Sketch-based 3D Object Retrieval Using Two Views and Visual Part Alignment
International audienceHand drawn figures are the imprints of shapes in human's mind. How a human expresses a shape is a consequence of how he or she visualizes it. A query-by-sketch 3D object retrieval application is closely tied to this concept from two aspects. First, describing sketches must involve elements in a figure that matter most to a human. Second, the representative 2D projection of the target 3D objects must be limited to ''the canonical views'' from a human cognition perspective. We advocate for these two rules by presenting a new approach for sketch-based 3D object retrieval that describes a 2D shape by the visual protruding parts of its silhouette. Furthermore, the proposed approach computes estimations of ''part occlusion'' and ''symmetry'' in 2D shapes in a new paradigm for viewpoint selection that represents 3D objects by only the two views corresponding to the minimum value of each