126 research outputs found
Pyramid Semantic Graph-based Global Point Cloud Registration with Low Overlap
Global point cloud registration is essential in many robotics tasks like loop
closing and relocalization. Unfortunately, the registration often suffers from
the low overlap between point clouds, a frequent occurrence in practical
applications due to occlusion and viewpoint change. In this paper, we propose a
graph-theoretic framework to address the problem of global point cloud
registration with low overlap. To this end, we construct a consistency graph to
facilitate robust data association and employ graduated non-convexity (GNC) for
reliable pose estimation, following the state-of-the-art (SoTA) methods.
Unlike previous approaches, we use semantic cues to scale down the dense
point clouds, thus reducing the problem size. Moreover, we address the
ambiguity arising from the consistency threshold by constructing a pyramid
graph with multi-level consistency thresholds. Then we propose a cascaded
gradient ascend method to solve the resulting densest clique problem and obtain
multiple pose candidates for every consistency threshold. Finally, fast
geometric verification is employed to select the optimal estimation from
multiple pose candidates. Our experiments, conducted on a self-collected indoor
dataset and the public KITTI dataset, demonstrate that our method achieves the
highest success rate despite the low overlap of point clouds and low semantic
quality. We have open-sourced our code
https://github.com/HKUST-Aerial-Robotics/Pagor for this project.Comment: Accepted by IROS202
Online Monocular Lane Mapping Using Catmull-Rom Spline
In this study, we introduce an online monocular lane mapping approach that
solely relies on a single camera and odometry for generating spline-based maps.
Our proposed technique models the lane association process as an assignment
issue utilizing a bipartite graph, and assigns weights to the edges by
incorporating Chamfer distance, pose uncertainty, and lateral sequence
consistency. Furthermore, we meticulously design control point initialization,
spline parameterization, and optimization to progressively create, expand, and
refine splines. In contrast to prior research that assessed performance using
self-constructed datasets, our experiments are conducted on the openly
accessible OpenLane dataset. The experimental outcomes reveal that our
suggested approach enhances lane association and odometry precision, as well as
overall lane map quality. We have open-sourced our code1 for this project.Comment: Accepted by IROS202
Multi-Session, Localization-oriented and Lightweight LiDAR Mapping Using Semantic Lines and Planes
In this paper, we present a centralized framework for multi-session LiDAR
mapping in urban environments, by utilizing lightweight line and plane map
representations instead of widely used point clouds. The proposed framework
achieves consistent mapping in a coarse-to-fine manner. Global place
recognition is achieved by associating lines and planes on the Grassmannian
manifold, followed by an outlier rejection-aided pose graph optimization for
map merging. Then a novel bundle adjustment is also designed to improve the
local consistency of lines and planes. In the experimental section, both public
and self-collected datasets are used to demonstrate efficiency and
effectiveness. Extensive results validate that our LiDAR mapping framework
could merge multi-session maps globally, optimize maps incrementally, and is
applicable for lightweight robot localization.Comment: Accepted by IROS202
SeasonDepth: Cross-Season Monocular Depth Prediction Dataset and Benchmark under Multiple Environments
Different environments pose a great challenge to the outdoor robust visual
perception for long-term autonomous driving and the generalization of
learning-based algorithms on different environmental effects is still an open
problem. Although monocular depth prediction has been well studied recently,
there is few work focusing on the robust learning-based depth prediction across
different environments, e.g. changing illumination and seasons, owing to the
lack of such a multi-environment real-world dataset and benchmark. To this end,
the first cross-season monocular depth prediction dataset and benchmark
SeasonDepth is built based on CMU Visual Localization dataset. To benchmark the
depth estimation performance under different environments, we investigate
representative and recent state-of-the-art open-source supervised,
self-supervised and domain adaptation depth prediction methods from KITTI
benchmark using several newly-formulated metrics. Through extensive
experimental evaluation on the proposed dataset, the influence of multiple
environments on performance and robustness is analyzed qualitatively and
quantitatively, showing that the long-term monocular depth prediction is still
challenging even with fine-tuning. We further give promising avenues that
self-supervised training and stereo geometry constraint help to enhance the
robustness to changing environments. The dataset is available on
https://seasondepth.github.io, and benchmark toolkit is available on
https://github.com/SeasonDepth/SeasonDepth.Comment: 19 pages, 13 figure
G3Reg: Pyramid Graph-based Global Registration using Gaussian Ellipsoid Model
This study introduces a novel framework, G3Reg, for fast and robust global
registration of LiDAR point clouds. In contrast to conventional complex
keypoints and descriptors, we extract fundamental geometric primitives
including planes, clusters, and lines (PCL) from the raw point cloud to obtain
low-level semantic segments. Each segment is formulated as a unified Gaussian
Ellipsoid Model (GEM) by employing a probability ellipsoid to ensure the ground
truth centers are encompassed with a certain degree of probability. Utilizing
these GEMs, we then present a distrust-and-verify scheme based on a Pyramid
Compatibility Graph for Global Registration (PAGOR). Specifically, we establish
an upper bound, which can be traversed based on the confidence level for
compatibility testing to construct the pyramid graph. Gradually, we solve
multiple maximum cliques (MAC) for each level of the graph, generating numerous
transformation candidates. In the verification phase, we adopt a precise and
efficient metric for point cloud alignment quality, founded on geometric
primitives, to identify the optimal candidate. The performance of the algorithm
is extensively validated on three publicly available datasets and a
self-collected multi-session dataset, without changing any parameter settings
in the experimental evaluation. The results exhibit superior robustness and
real-time performance of the G3Reg framework compared to state-of-the-art
methods. Furthermore, we demonstrate the potential for integrating individual
GEM and PAGOR components into other algorithmic frameworks to enhance their
efficacy. To advance further research and promote community understanding, we
have publicly shared the source code.Comment: Under revie
Characterization and Expression Patterns of Auxin Response Factors in Wheat
Auxin response factors (ARFs) are important transcription factors involved in both the auxin signaling pathway and the regulatory development of various plant organs. In this study, 23 TaARF members encoded by a total of 68 homeoalleles were isolated from 18 wheat chromosomes (excluding chromosome 4). The TaARFs, including their conserved domains, exon/intron structures, related microRNAs, and alternative splicing (AS) variants, were then characterized. Phylogenetic analysis revealed that members of the TaARF family share close homology with ARFs in other grass species. qRT-PCR analyses revealed that 20 TaARF members were expressed in different organs and tissues and that the expression of some members significantly differed in the roots, stems, and leaves of wheat seedlings in response to exogenous auxin treatment. Moreover, protein network analyses and co-expression results showed that TaTIR1–TaARF15/18/19–TaIAA13 may interact at both the protein and genetic levels. The results of subsequent evolutionary analyses showed that three transcripts of TaARF15 in the A subgenome of wheat exhibited high evolutionary rate and underwent positive selection. Transgenic analyses indicated that TaARF15-A.1 promoted the growth of roots and leaves of Arabidopsis thaliana and was upregulated in the overexpression plants after auxin treatment. Our results will provide reference information for subsequent research and utilization of the TaARF gene family
Development of Sequence-Tagged Site Marker Set for Identification of J, JS, and St Sub-genomes of Thinopyrum intermedium in Wheat Background
Thinopyrum intermedium (2n = 6x = 42, JJJSJSStSt) is one of the important resources for the wheat improvement. So far, a few Th. intermedium (Thi)-specific molecular markers have been reported, but the number is far from enough to meet the need of identifying alien fragments in wheat-Th. intermedium hybrids. In this study, 5,877,409 contigs were assembled using the Th. intermedium genotyping-by-sequencing (GBS) data. We obtained 5,452 non-redundant contigs containing mapped Thi-GBS markers with less than 20% similarity to the wheat genome and developed 2,019 sequence-tagged site (STS) molecular markers. Among the markers designed, 745 Thi-specific markers with amplification products in Th. intermedium but not in eight wheat landraces were further selected. The distribution of these markers in different homologous groups of Th. intermedium varied from 47 (7/12/28 on 6J/6St/6JS) to 183 (54/62/67 on 7J/7St/7JS). Furthermore, the effectiveness of these Thi-specific markers was verified using wheat-Th. intermedium partial amphidiploids, addition lines, substitution lines, and translocation lines. Markers developed in this study provide a convenient, rapid, reliable, and economical method for identifying Th. intermedium chromosomes in wheat. In addition, this set of Thi-specific markers can also be used to estimate genetic and physical locations of Th. intermedium chromatin in the introgression lines, thus providing valuable information for follow-up studies such as alien gene mining
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