V SEGINFO - “Recuperando Dados (Data Carving) em Mídias e em Redes”
Finish Adaptive Space Carving Anselmo A. Montenegro †, Marcelo Gattass ‡, Paulo Carvalho † and...
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Finish Adaptive Space Carving Adaptive Space Carving Anselmo A. Montenegro Anselmo A. Montenegro † † , Marcelo Gattass , Marcelo Gattass ‡ ‡ , P , P aulo Carvalho aulo Carvalho † † and L and L uiz Velho uiz Velho † † † † [anselmo,lvelho,pcezar]@visgraf.impa.br, [anselmo,lvelho,pcezar]@visgraf.impa.br, ‡ ‡ [email protected] [email protected] 3D object reconstruction is one of the most 3D object reconstruction is one of the most investigated topics in computer graphics and investigated topics in computer graphics and vision. Among different techniques, image vision. Among different techniques, image based reconstruction is considered one of the based reconstruction is considered one of the most promising as high quality digital cameras most promising as high quality digital cameras are becoming a commodity hardware. are becoming a commodity hardware. Problems with photometric approaches: Problems with photometric approaches: Registration and evaluation of Registration and evaluation of thousands thousands of of individual elements. individual elements. Solution: Solution: Registration based on projective texture Registration based on projective texture mapping. mapping. Photo-consitency evaluation done by GPU Photo-consitency evaluation done by GPU programming programming . . Volumetric carving is a Volumetric carving is a very common technique very common technique use for image based use for image based reconstruction. It may reconstruction. It may use silhouette and/or use silhouette and/or photometric photometric information. information. Silhouette based Silhouette based methods were methods were successfully used in successfully used in real-time real-time reconstructions. This reconstructions. This is not the case when is not the case when we consider photometric we consider photometric approaches. approaches. Still some problems: Still some problems: Too much elements Too much elements Memory waste Memory waste Solution: Solution: Hierarchical Hierarchical representation of representation of scene space scene space Refinement approach Refinement approach Adaptive Carving Adaptive Carving Backgroun d estimatio n Camera calibrati on Image capture Object segmentat ion Reconstruct ion by Adaptive Space Carving Fixed pre-calibrated cameras Fixed pre-calibrated cameras setup setup Calibration by model recongnition Adaptive space carving: Adaptive space carving: • Works on an octree representation of the scene Works on an octree representation of the scene space. space. • The reconstruction is obtained by a refinement The reconstruction is obtained by a refinement process based on photo-consistency tests. process based on photo-consistency tests. • Uses photometric and silhouette information in Uses photometric and silhouette information in multiresolution to detect coarse empty regions multiresolution to detect coarse empty regions as soon as possible. as soon as possible. • Classification of the cells: Classification of the cells: CONSISTENT, INCONSISTENT CONSISTENT, INCONSISTENT and UNDEFINED. and UNDEFINED. • Undefined cells are subdivided and classified Undefined cells are subdivided and classified in later stages. in later stages. Level 5 Segmentation based on intervals of confidence Adaptive Space Carving Adaptive Space Carving Space Carving Space Carving No cell subdivided ? Last registration plane of the level? Subdivide undefined cells and colorize photo-consistent cells. Update visibility maps. Test the consistency of the non- classified cells intersected by the current registration plane Project images on the current registration plane with resolution compatible to the octree level Algorithm Algorithm Levels of Levels of refinement refinement Level 6 Level7 Level 8 Zoom Fixed cameras reconstruction Fixed cameras reconstruction results results Final considerations Final considerations In this work we only explored convencional GPU In this work we only explored convencional GPU hardware accelerated operations, as in the hardware accelerated operations, as in the registration step by projective texture mapping . registration step by projective texture mapping . The mechanism of copying framebuffer information The mechanism of copying framebuffer information to main memory introduces significant overhead to to main memory introduces significant overhead to the overall processing time. We believe that by the overall processing time. We believe that by combining our adaptive approach with photo- combining our adaptive approach with photo- consistency test done by GPU programming we can consistency test done by GPU programming we can obtain considerable gains in efficiency. obtain considerable gains in efficiency. YES YES NO NO YES YES NO NO Process next Process next registration plane registration plane Process next octree Process next octree refinement level refinement level Determine the registration planes at the current level Initialize the octree root cell with the bounding box of the scene Images and segmentat ion Visibility and noise maps
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Transcript of Finish Adaptive Space Carving Anselmo A. Montenegro †, Marcelo Gattass ‡, Paulo Carvalho † and...
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Adaptive Space CarvingAdaptive Space CarvingAnselmo A. MontenegroAnselmo A. Montenegro††, Marcelo Gattass, Marcelo Gattass‡‡ , P, Paulo Carvalhoaulo Carvalho†† and Land Luiz Velhouiz Velho††
††[anselmo,lvelho,pcezar]@visgraf.impa.br, [anselmo,lvelho,pcezar]@visgraf.impa.br, ‡‡ [email protected] [email protected]
3D object reconstruction is one of the most investigated topics 3D object reconstruction is one of the most investigated topics in computer graphics and vision. Among different techniques, in computer graphics and vision. Among different techniques, image based reconstruction is considered one of the most image based reconstruction is considered one of the most promising as high quality digital cameras are becoming a promising as high quality digital cameras are becoming a commodity hardware.commodity hardware.
Problems with photometric approaches:Problems with photometric approaches:Registration and evaluation of Registration and evaluation of thousandsthousands of individual of individual elements.elements.
Solution: Solution: Registration based on projective texture mapping.Registration based on projective texture mapping.Photo-consitency evaluation done by GPU programmingPhoto-consitency evaluation done by GPU programming..
Volumetric carving is a very Volumetric carving is a very common technique use for common technique use for image based reconstruction. It image based reconstruction. It may use silhouette and/or may use silhouette and/or photometric information. photometric information. Silhouette based methods Silhouette based methods were successfully used in real-were successfully used in real-time reconstructions. This is time reconstructions. This is not the case when we consider not the case when we consider photometric approaches.photometric approaches.
Still some problems:Still some problems: Too much elementsToo much elements Memory wasteMemory waste
Solution:Solution:Hierarchical representation Hierarchical representation of scene spaceof scene spaceRefinement approachRefinement approachAdaptive CarvingAdaptive Carving
Background estimation
Camera calibration
Image capture
Object segmentation
Reconstruction by Adaptive
Space Carving
Fixed pre-calibrated cameras setupFixed pre-calibrated cameras setup
Calibration by model recongnition
Adaptive space carving:Adaptive space carving:
•Works on an octree representation of the scene space.Works on an octree representation of the scene space.
•The reconstruction is obtained by a refinement process based The reconstruction is obtained by a refinement process based on photo-consistency tests.on photo-consistency tests.
•Uses photometric and silhouette information in multiresolution to Uses photometric and silhouette information in multiresolution to detect coarse empty regions as soon as possible.detect coarse empty regions as soon as possible.
•Classification of the cells: Classification of the cells: CONSISTENT, INCONSISTENT and UNDEFINED.CONSISTENT, INCONSISTENT and UNDEFINED.
•Undefined cells are subdivided and classified in later stages.Undefined cells are subdivided and classified in later stages.
Level 5
Segmentation based on intervals of confidence
Adaptive Space CarvingAdaptive Space CarvingSpace CarvingSpace Carving
No cell subdivided ?
Last registration plane of the level?
Subdivide undefined cells and colorize photo-consistent cells. Update visibility maps.
Test the consistency of the non- classified cells intersected by the current registration plane
Project images on the current registration plane with resolution compatible to the octree level
AlgorithmAlgorithm Levels of refinementLevels of refinement
Level 6
Level7 Level 8
Zoom
Fixed cameras reconstruction resultsFixed cameras reconstruction results
Final considerationsFinal considerations
In this work we only explored convencional GPU hardware In this work we only explored convencional GPU hardware accelerated operations, as in the registration step by projective accelerated operations, as in the registration step by projective texture mapping . The mechanism of copying framebuffer texture mapping . The mechanism of copying framebuffer information to main memory introduces significant overhead to the information to main memory introduces significant overhead to the overall processing time. We believe that by combining our adaptive overall processing time. We believe that by combining our adaptive approach with photo-consistency test done by GPU programming approach with photo-consistency test done by GPU programming we can obtain considerable gains in efficiency. we can obtain considerable gains in efficiency.
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NONO
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Determine the registration planes at the current level
Initialize the octree root cell with the bounding box of the scene
Images and
segmentation
Visibility and noise maps
