9 research outputs found
Optoelectronic and photogrammetric measuring systems
Disertace se zabývá analýzou a návrhem optoelektronických a fotogrammetrických měřících systémů. Obsahuje konkrétní návrhy optoelektronických bezdotykových měřičů ploch rovinných objektů, případně plošné projekce 3D objektů včetně analýzy dosažitelné přesnosti měření. V další části věnované stereofotogrammetrii se zabývá principy rekonstrukce prostorových souřadnic snímaných objektů, metodami automatické kalibrace kamer, postupy v ztotožňování bodů na snímcích spolu s analýzou dosažitelné přesnosti v určování sledovaných parametrů. Součástí práce je vyvinutý testovací program v němž jsou uvedené postupy implementovány a který umožňuje praktickou aplikaci stereofotogrammetrického systému pro pořizování prostorových souřadnic trojrozměrných objektů.Dissertation deals with analysis and design of optoelectronic and photogrammetric measuring systems. Specific design of optoelectronic contactless flat object area meters with analysis of attainable measurement accuracy is described. Next part is dedicated to stereophotogrammetry - principles of 3D reconstructions, methods of camera self-calibration and matching points in images are described. The analysis of attainable accuracy of monitored parameters is discussed too. Finally, the test program with implemented described routines is introduced. This test program enables practical aplication of stereophotogrammetric system for taking spatial coordinates of 3D objects.
Remote Sensing for International Stability and Security - Integrating GMOSS Achievements in GMES
The Joint Research Centre of the European Commission hosted a two-day workshop "Remote sensing for international stability and security: integrating GMOSS achievements in GMES". Its aim was to disseminate the scientific and technical achievements of the Global Monitoring for Security and Stability (GMOSS) network of excellence to partners of ongoing and future GMES projects such as RESPOND, LIMES, RISK-EOS,PREVIEW, BOSS4GMES, SAFER, G-MOSAIC.
The objectives of this workshop were:
¿ To bring together scientific and technical people from the GMOSS NoE and from thematically related GMES projects.
¿ To discuss and compare alternative technical solutions (e.g. final experimental understanding from GMOSS, operational procedures applied in projects such as RESPOND, pre-operational application procedures foreseen from LIMES, etc.)
¿ To draft a list of technical and scientific challenges relevant in the next future.
¿ To open GMOSS to a wider forum in the JRC
This report contains abstracts of the fifteen contributions presented by European researchers. The different presentations addressed pre-processing, feature recognition, change detection and applications which represents also the structure of the report. The second part includes poster abstracts presented during a separate poster session.JRC.G.2-Global security and crisis managemen
Stereo vision based on compressed feature correlation and graph cut
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.Includes bibliographical references (p. 131-145).This dissertation has developed a fast and robust algorithm to solve the dense correspondence problem with a good performance in untextured regions by merging Sparse Array Correlation from the computational fluids community into graph cut from the computer vision community. The proposed methodology consists of two independent modules. The first module is named Compressed Feature Correlation which is originated from Particle Image Velocimetry (PIV). The algorithm uses an image compression scheme that retains pixel values in high-intensity gradient areas while eliminating pixels with little correlation information in smooth surface regions resulting in a highly reduced image datasets. In addition, by utilizing an error correlation function, pixel comparisons are made through single integer calculations eliminating time consuming multiplication and floating point arithmetic. Unlike the traditional fixed window sorting scheme, adaptive correlation window positioning is implemented by dynamically placing strong features at the center of each correlation window. A confidence measure is developed to validate correlation outputs. The sparse depth map generated by this ultra-fast Compressed Feature Correlation may either serve as inputs to global methods or be interpolated into dense depth map when object boundaries are clearly defined. The second module enables a modified graph cut algorithm with an improved energy model that accepts prior information by fixing data energy penalties. The image pixels with known disparity values stabilize and speed up global optimization. As a result less iterations are necessary and sensitivity to parameters is reduced.(cont.) An efficient hybrid approach is implemented based on the above two modules. By coupling a simpler and much less expensive algorithm, Compressed Feature Correlation, with a more expensive algorithm, graph cut, the computational expense of the hybrid calculation is one third of performing the entire calculation using the more expensive of the two algorithms, while accuracy and robustness are improved at the same time. Qualitative and quantitative results on both simulated disparities and real stereo images are presented.by Sheng Sarah Tan.Ph.D
A family of stereoscopic image compression algorithms using wavelet transforms
With the standardization of JPEG-2000, wavelet-based image and video
compression technologies are gradually replacing the popular DCT-based methods. In
parallel to this, recent developments in autostereoscopic display technology is now
threatening to revolutionize the way in which consumers are used to enjoying the
traditional 2-D display based electronic media such as television, computer and
movies. However, due to the two-fold bandwidth/storage space requirement of
stereoscopic imaging, an essential requirement of a stereo imaging system is efficient
data compression.
In this thesis, seven wavelet-based stereo image compression algorithms are
proposed, to take advantage of the higher data compaction capability and better
flexibility of wavelets. [Continues.
A family of stereoscopic image compression algorithms using wavelet transforms
With the standardization of JPEG-2000, wavelet-based image and video
compression technologies are gradually replacing the popular DCT-based methods. In
parallel to this, recent developments in autostereoscopic display technology is now
threatening to revolutionize the way in which consumers are used to enjoying the
traditional 2D display based electronic media such as television, computer and
movies. However, due to the two-fold bandwidth/storage space requirement of
stereoscopic imaging, an essential requirement of a stereo imaging system is efficient
data compression.
In this thesis, seven wavelet-based stereo image compression algorithms are
proposed, to take advantage of the higher data compaction capability and better
flexibility of wavelets. In the proposed CODEC I, block-based disparity
estimation/compensation (DE/DC) is performed in pixel domain. However, this
results in an inefficiency when DWT is applied on the whole predictive error image
that results from the DE process. This is because of the existence of artificial block
boundaries between error blocks in the predictive error image. To overcome this
problem, in the remaining proposed CODECs, DE/DC is performed in the wavelet
domain. Due to the multiresolution nature of the wavelet domain, two methods of
disparity estimation and compensation have been proposed. The first method is
performing DEJDC in each subband of the lowest/coarsest resolution level and then
propagating the disparity vectors obtained to the corresponding subbands of
higher/finer resolution. Note that DE is not performed in every subband due to the
high overhead bits that could be required for the coding of disparity vectors of all
subbands. This method is being used in CODEC II. In the second method, DEJDC is
performed m the wavelet-block domain. This enables disparity estimation to be
performed m all subbands simultaneously without increasing the overhead bits
required for the coding disparity vectors. This method is used by CODEC III.
However, performing disparity estimation/compensation in all subbands would result
in a significant improvement of CODEC III. To further improve the performance of
CODEC ill, pioneering wavelet-block search technique is implemented in CODEC
IV. The pioneering wavelet-block search technique enables the right/predicted image
to be reconstructed at the decoder end without the need of transmitting the disparity
vectors. In proposed CODEC V, pioneering block search is performed in all subbands
of DWT decomposition which results in an improvement of its performance. Further,
the CODEC IV and V are able to perform at very low bit rates(< 0.15 bpp). In
CODEC VI and CODEC VII, Overlapped Block Disparity Compensation (OBDC) is
used with & without the need of coding disparity vector. Our experiment results
showed that no significant coding gains could be obtained for these CODECs over
CODEC IV & V.
All proposed CODECs m this thesis are wavelet-based stereo image coding
algorithms that maximise the flexibility and benefits offered by wavelet transform
technology when applied to stereo imaging. In addition the use of a baseline-JPEG
coding architecture would enable the easy adaptation of the proposed algorithms
within systems originally built for DCT-based coding. This is an important feature
that would be useful during an era where DCT-based technology is only slowly being
phased out to give way for DWT based compression technology.
In addition, this thesis proposed a stereo image coding algorithm that uses JPEG-2000
technology as the basic compression engine. The proposed CODEC, named RASTER
is a rate scalable stereo image CODEC that has a unique ability to preserve the image
quality at binocular depth boundaries, which is an important requirement in the design
of stereo image CODEC. The experimental results have shown that the proposed
CODEC is able to achieve PSNR gains of up to 3.7 dB as compared to directly
transmitting the right frame using JPEG-2000