2,229 research outputs found
Transformer-based Multimodal Change Detection with Multitask Consistency Constraints
Change detection plays a fundamental role in Earth observation for analyzing
temporal iterations over time. However, recent studies have largely neglected
the utilization of multimodal data that presents significant practical and
technical advantages compared to single-modal approaches. This research focuses
on leveraging digital surface model (DSM) data and aerial images captured at
different times for detecting change beyond 2D. We observe that the current
change detection methods struggle with the multitask conflicts between semantic
and height change detection tasks. To address this challenge, we propose an
efficient Transformer-based network that learns shared representation between
cross-dimensional inputs through cross-attention. It adopts a consistency
constraint to establish the multimodal relationship, which involves obtaining
pseudo change through height change thresholding and minimizing the difference
between semantic and pseudo change within their overlapping regions. A
DSM-to-image multimodal dataset encompassing three cities in the Netherlands
was constructed. It lays a new foundation for beyond-2D change detection from
cross-dimensional inputs. Compared to five state-of-the-art change detection
methods, our model demonstrates consistent multitask superiority in terms of
semantic and height change detection. Furthermore, the consistency strategy can
be seamlessly adapted to the other methods, yielding promising improvements
Deep learning in remote sensing: a review
Standing at the paradigm shift towards data-intensive science, machine
learning techniques are becoming increasingly important. In particular, as a
major breakthrough in the field, deep learning has proven as an extremely
powerful tool in many fields. Shall we embrace deep learning as the key to all?
Or, should we resist a 'black-box' solution? There are controversial opinions
in the remote sensing community. In this article, we analyze the challenges of
using deep learning for remote sensing data analysis, review the recent
advances, and provide resources to make deep learning in remote sensing
ridiculously simple to start with. More importantly, we advocate remote sensing
scientists to bring their expertise into deep learning, and use it as an
implicit general model to tackle unprecedented large-scale influential
challenges, such as climate change and urbanization.Comment: Accepted for publication IEEE Geoscience and Remote Sensing Magazin
Automatic Alignment of 3D Multi-Sensor Point Clouds
Automatic 3D point cloud alignment is a major research topic in photogrammetry, computer vision and computer graphics. In this research, two keypoint feature matching approaches have been developed and proposed for the automatic alignment of 3D point clouds, which have been acquired from different sensor platforms and are in different 3D conformal coordinate systems.
The first proposed approach is based on 3D keypoint feature matching. First, surface curvature information is utilized for scale-invariant 3D keypoint extraction. Adaptive non-maxima suppression (ANMS) is then applied to retain the most distinct and well-distributed set of keypoints. Afterwards, every keypoint is characterized by a scale, rotation and translation invariant 3D surface descriptor, called the radial geodesic distance-slope histogram. Similar keypoints descriptors on the source and target datasets are then matched using bipartite graph matching, followed by a modified-RANSAC for outlier removal.
The second proposed method is based on 2D keypoint matching performed on height map images of the 3D point clouds. Height map images are generated by projecting the 3D point clouds onto a planimetric plane. Afterwards, a multi-scale wavelet 2D keypoint detector with ANMS is proposed to extract keypoints on the height maps. Then, a scale, rotation and translation-invariant 2D descriptor referred to as the Gabor, Log-Polar-Rapid Transform descriptor is computed for all keypoints. Finally, source and target height map keypoint correspondences are determined using a bi-directional nearest neighbour matching, together with the modified-RANSAC for outlier removal.
Each method is assessed on multi-sensor, urban and non-urban 3D point cloud datasets. Results show that unlike the 3D-based method, the height map-based approach is able to align source and target datasets with differences in point density, point distribution and missing point data. Findings also show that the 3D-based method obtained lower transformation errors and a greater number of correspondences when the source and target have similar point characteristics. The 3D-based approach attained absolute mean alignment differences in the range of 0.23m to 2.81m, whereas the height map approach had a range from 0.17m to 1.21m. These differences meet the proximity requirements of the data characteristics and the further application of fine co-registration approaches
Recent Advances in Image Restoration with Applications to Real World Problems
In the past few decades, imaging hardware has improved tremendously in terms of resolution, making widespread usage of images in many diverse applications on Earth and planetary missions. However, practical issues associated with image acquisition are still affecting image quality. Some of these issues such as blurring, measurement noise, mosaicing artifacts, low spatial or spectral resolution, etc. can seriously affect the accuracy of the aforementioned applications. This book intends to provide the reader with a glimpse of the latest developments and recent advances in image restoration, which includes image super-resolution, image fusion to enhance spatial, spectral resolution, and temporal resolutions, and the generation of synthetic images using deep learning techniques. Some practical applications are also included
Remote sensing image fusion on 3D scenarios: A review of applications for agriculture and forestry
Three-dimensional (3D) image mapping of real-world scenarios has a great potential to provide the user with a
more accurate scene understanding. This will enable, among others, unsupervised automatic sampling of
meaningful material classes from the target area for adaptive semi-supervised deep learning techniques. This
path is already being taken by the recent and fast-developing research in computational fields, however, some
issues related to computationally expensive processes in the integration of multi-source sensing data remain.
Recent studies focused on Earth observation and characterization are enhanced by the proliferation of Unmanned
Aerial Vehicles (UAV) and sensors able to capture massive datasets with a high spatial resolution. In this scope,
many approaches have been presented for 3D modeling, remote sensing, image processing and mapping, and
multi-source data fusion. This survey aims to present a summary of previous work according to the most relevant
contributions for the reconstruction and analysis of 3D models of real scenarios using multispectral, thermal and
hyperspectral imagery. Surveyed applications are focused on agriculture and forestry since these fields
concentrate most applications and are widely studied. Many challenges are currently being overcome by recent
methods based on the reconstruction of multi-sensorial 3D scenarios. In parallel, the processing of large image
datasets has recently been accelerated by General-Purpose Graphics Processing Unit (GPGPU) approaches that
are also summarized in this work. Finally, as a conclusion, some open issues and future research directions are
presented.European Commission 1381202-GEU
PYC20-RE-005-UJA
IEG-2021Junta de Andalucia 1381202-GEU
PYC20-RE-005-UJA
IEG-2021Instituto de Estudios GiennesesEuropean CommissionSpanish Government UIDB/04033/2020DATI-Digital Agriculture TechnologiesPortuguese Foundation for Science and Technology 1381202-GEU
FPU19/0010
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