410 research outputs found
Detail-preserving and Content-aware Variational Multi-view Stereo Reconstruction
Accurate recovery of 3D geometrical surfaces from calibrated 2D multi-view
images is a fundamental yet active research area in computer vision. Despite
the steady progress in multi-view stereo reconstruction, most existing methods
are still limited in recovering fine-scale details and sharp features while
suppressing noises, and may fail in reconstructing regions with few textures.
To address these limitations, this paper presents a Detail-preserving and
Content-aware Variational (DCV) multi-view stereo method, which reconstructs
the 3D surface by alternating between reprojection error minimization and mesh
denoising. In reprojection error minimization, we propose a novel inter-image
similarity measure, which is effective to preserve fine-scale details of the
reconstructed surface and builds a connection between guided image filtering
and image registration. In mesh denoising, we propose a content-aware
-minimization algorithm by adaptively estimating the value and
regularization parameters based on the current input. It is much more promising
in suppressing noise while preserving sharp features than conventional
isotropic mesh smoothing. Experimental results on benchmark datasets
demonstrate that our DCV method is capable of recovering more surface details,
and obtains cleaner and more accurate reconstructions than state-of-the-art
methods. In particular, our method achieves the best results among all
published methods on the Middlebury dino ring and dino sparse ring datasets in
terms of both completeness and accuracy.Comment: 14 pages,16 figures. Submitted to IEEE Transaction on image
processin
3D Surface Reconstruction of Underwater Objects
In this paper, we propose a novel technique to reconstruct 3D surface of an
underwater object using stereo images. Reconstructing the 3D surface of an
underwater object is really a challenging task due to degraded quality of
underwater images. There are various reason of quality degradation of
underwater images i.e., non-uniform illumination of light on the surface of
objects, scattering and absorption effects. Floating particles present in
underwater produces Gaussian noise on the captured underwater images which
degrades the quality of images. The degraded underwater images are preprocessed
by applying homomorphic, wavelet denoising and anisotropic filtering
sequentially. The uncalibrated rectification technique is applied to
preprocessed images to rectify the left and right images. The rectified left
and right image lies on a common plane. To find the correspondence points in a
left and right images, we have applied dense stereo matching technique i.e.,
graph cut method. Finally, we estimate the depth of images using triangulation
technique. The experimental result shows that the proposed method reconstruct
3D surface of underwater objects accurately using captured underwater stereo
images.Comment: International Journal of Computer Applications (2012
A CNN Based Approach for the Point-Light Photometric Stereo Problem
Reconstructing the 3D shape of an object using several images under different
light sources is a very challenging task, especially when realistic assumptions
such as light propagation and attenuation, perspective viewing geometry and
specular light reflection are considered. Many of works tackling Photometric
Stereo (PS) problems often relax most of the aforementioned assumptions.
Especially they ignore specular reflection and global illumination effects. In
this work, we propose a CNN-based approach capable of handling these realistic
assumptions by leveraging recent improvements of deep neural networks for
far-field Photometric Stereo and adapt them to the point light setup. We
achieve this by employing an iterative procedure of point-light PS for shape
estimation which has two main steps. Firstly we train a per-pixel CNN to
predict surface normals from reflectance samples. Secondly, we compute the
depth by integrating the normal field in order to iteratively estimate light
directions and attenuation which is used to compensate the input images to
compute reflectance samples for the next iteration.
Our approach sigificantly outperforms the state-of-the-art on the DiLiGenT
real world dataset. Furthermore, in order to measure the performance of our
approach for near-field point-light source PS data, we introduce LUCES the
first real-world 'dataset for near-fieLd point light soUrCe photomEtric Stereo'
of 14 objects of different materials were the effects of point light sources
and perspective viewing are a lot more significant. Our approach also
outperforms the competition on this dataset as well. Data and test code are
available at the project page.Comment: arXiv admin note: text overlap with arXiv:2009.0579
GeoNet: Unsupervised Learning of Dense Depth, Optical Flow and Camera Pose
We propose GeoNet, a jointly unsupervised learning framework for monocular
depth, optical flow and ego-motion estimation from videos. The three components
are coupled by the nature of 3D scene geometry, jointly learned by our
framework in an end-to-end manner. Specifically, geometric relationships are
extracted over the predictions of individual modules and then combined as an
image reconstruction loss, reasoning about static and dynamic scene parts
separately. Furthermore, we propose an adaptive geometric consistency loss to
increase robustness towards outliers and non-Lambertian regions, which resolves
occlusions and texture ambiguities effectively. Experimentation on the KITTI
driving dataset reveals that our scheme achieves state-of-the-art results in
all of the three tasks, performing better than previously unsupervised methods
and comparably with supervised ones.Comment: Accepted to CVPR 2018; Code will be made available at
https://github.com/yzcjtr/GeoNe
Detailed and Practical 3D Reconstruction with Advanced Photometric Stereo Modelling
Object 3D reconstruction has always been one of the main objectives of computer vision. After many decades of research, most techniques are still unsuccessful at recovering high resolution surfaces, especially for objects with limited surface texture. Moreover, most shiny materials are particularly hard to reconstruct.
Photometric Stereo (PS), which operates by capturing multiple images under changing illumination has traditionally been one of the most successful techniques at recovering a large amount of surface details, by exploiting the relationship between shading and local shape. However, using PS has been highly impractical because most approaches are only applicable in a very controlled lab setting and limited to objects experiencing diffuse reflection.
Nevertheless, recent advances in differential modelling have made complicated Photometric Stereo models possible and variational optimisations for these kinds of models show remarkable resilience to real world imperfections such as non-Gaussian noise and other outliers. Thus, a highly accurate, photometric-based reconstruction system is now possible.
The contribution of this thesis is threefold. First of all, the Photometric Stereo model is extended in order to be able to deal with arbitrary ambient lighting. This is a step towards acquisition in a non-fully controlled lab setting. Secondly, the need for a priori knowledge of the light source brightness and attenuation characteristics is relaxed as an alternating optimisation procedure is proposed which is able to estimate these parameters. This extension allows for quick acquisition with inexpensive LEDs that exhibit unpredictable illumination characteristics (flickering etc). Finally, a volumetric parameterisation is proposed which allows one to tackle the multi-view Photometric Stereo problem in a similar manner, in a simple unified differential model. This final extension allows for complete object reconstruction merging information from multiple images taken from multiple viewpoints and variable illumination.
The theoretical work in this thesis is experimentally evaluated in a number of challenging real world experiments, with data captured by custom-made hardware. In addition, the applicability of the generality of the proposed models is demonstrated by presenting a differential model for the shape of polarisation problem, which leads to a unified optimisation problem, fusing information from both methods. This allows for the acquisition of geometrical information about objects such as semi-transparent glass, hitherto hard to deal with
cvpaper.challenge in 2016: Futuristic Computer Vision through 1,600 Papers Survey
The paper gives futuristic challenges disscussed in the cvpaper.challenge. In
2015 and 2016, we thoroughly study 1,600+ papers in several
conferences/journals such as CVPR/ICCV/ECCV/NIPS/PAMI/IJCV
Learning non-rigid surface reconstruction from spatio-temporal image patches
We present a method to reconstruct a dense spatio-temporal depth map of a
non-rigidly deformable object directly from a video sequence. The estimation of
depth is performed locally on spatio-temporal patches of the video, and then
the full depth video of the entire shape is recovered by combining them
together. Since the geometric complexity of a local spatio-temporal patch of a
deforming non-rigid object is often simple enough to be faithfully represented
with a parametric model, we artificially generate a database of small deforming
rectangular meshes rendered with different material properties and light
conditions, along with their corresponding depth videos, and use such data to
train a convolutional neural network. We tested our method on both synthetic
and Kinect data and experimentally observed that the reconstruction error is
significantly lower than the one obtained using other approaches like
conventional non-rigid structure from motion
A CNN Based Approach for the Near-Field Photometric Stereo Problem
Reconstructing the 3D shape of an object using several images under different
light sources is a very challenging task, especially when realistic assumptions
such as light propagation and attenuation, perspective viewing geometry and
specular light reflection are considered. Many of works tackling Photometric
Stereo (PS) problems often relax most of the aforementioned assumptions.
Especially they ignore specular reflection and global illumination effects. In
this work, we propose the first CNN based approach capable of handling these
realistic assumptions in Photometric Stereo. We leverage recent improvements of
deep neural networks for far-field Photometric Stereo and adapt them to near
field setup. We achieve this by employing an iterative procedure for shape
estimation which has two main steps. Firstly we train a per-pixel CNN to
predict surface normals from reflectance samples. Secondly, we compute the
depth by integrating the normal field in order to iteratively estimate light
directions and attenuation which is used to compensate the input images to
compute reflectance samples for the next iteration. To the best of our
knowledge this is the first near-field framework which is able to accurately
predict 3D shape from highly specular objects. Our method outperforms competing
state-of-the-art near-field Photometric Stereo approaches on both synthetic and
real experiments
PlaNeRF: SVD Unsupervised 3D Plane Regularization for NeRF Large-Scale Scene Reconstruction
Neural Radiance Fields (NeRF) enable 3D scene reconstruction from 2D images
and camera poses for Novel View Synthesis (NVS). Although NeRF can produce
photorealistic results, it often suffers from overfitting to training views,
leading to poor geometry reconstruction, especially in low-texture areas. This
limitation restricts many important applications which require accurate
geometry, such as extrapolated NVS, HD mapping and scene editing. To address
this limitation, we propose a new method to improve NeRF's 3D structure using
only RGB images and semantic maps. Our approach introduces a novel plane
regularization based on Singular Value Decomposition (SVD), that does not rely
on any geometric prior. In addition, we leverage the Structural Similarity
Index Measure (SSIM) in our loss design to properly initialize the volumetric
representation of NeRF. Quantitative and qualitative results show that our
method outperforms popular regularization approaches in accurate geometry
reconstruction for large-scale outdoor scenes and achieves SoTA rendering
quality on the KITTI-360 NVS benchmark.Comment: 14 pages, 7 figure
Neural apparent BRDF fields for multiview photometric stereo
We propose to tackle the multiview photometric stereo problem using an
extension of Neural Radiance Fields (NeRFs), conditioned on light source
direction. The geometric part of our neural representation predicts surface
normal direction, allowing us to reason about local surface reflectance. The
appearance part of our neural representation is decomposed into a neural
bidirectional reflectance function (BRDF), learnt as part of the fitting
process, and a shadow prediction network (conditioned on light source
direction) allowing us to model the apparent BRDF. This balance of learnt
components with inductive biases based on physical image formation models
allows us to extrapolate far from the light source and viewer directions
observed during training. We demonstrate our approach on a multiview
photometric stereo benchmark and show that competitive performance can be
obtained with the neural density representation of a NeRF.Comment: 9 pages, 6 figures, 1 tabl
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