The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
David J. Kriegman - One of the best experts on this subject based on the ideXlab platform.
-
Helmholtz Stereopsis: Exploiting Reciprocity for Surface Reconstruction
International Journal of Computer Vision, 2002Co-Authors: Todd E. Zickler, P.n. Peter N Peter N Belhumeur, David J. KriegmanAbstract:We present a method—termed Helmholtz stereopsis—for reconstructing the geometry of objects from a collection of images. Unlike existing methods for surface reconstruction (e.g., stereo vision, structure from motion, photometric stereopsis), Helmholtz stereopsis makes no assumptions about the nature of the bidirectional reflectance distribution functions (BRDFs) of objects. This new method of multinocular stereopsis exploits Helmholtz reciprocity by choosing pairs of light source and camera positions that guarantee that the ratio of the emitted radiance to the Incident Irradiance is the same for corresponding points in the two images. The method provides direct estimates of both depth and surface normals, and consequently weds the advantages of both conventional stereopsis and photometric stereopsis. Results from our implementation lend empirical support to our technique.
-
ECCV (3) - Helmholtz Stereopsis: Exploiting Reciprocity for Surface Reconstruction
Computer Vision — ECCV 2002, 2002Co-Authors: Todd E. Zickler, P.n. Peter N Peter N Belhumeur, David J. KriegmanAbstract:We present a method - termed Helmholtz stereopsis - for reconstructing the geometry of objects from a collection of images. Unlike most existing methods for surface reconstruction (e.g., stereo vision, structure from motion, photometric stereo), Helmholtz stereopsis makes no assumptions about the nature of the bidirectional reflectance distribution functions (BRDFs) of objects. This new method of multinocular stereopsis exploits Helmholtz reciprocity by choosing pairs of light source and camera positions that guarantee that the ratio of the emitted radiance to the Incident Irradiance is the same for corresponding points in the two images. The method provides direct estimates of both depth and field of surface normals, and consequently weds the advantages of both conventional and photometric stereopsis. Results from our implementations lend empirical support to our technique.
Todd E. Zickler - One of the best experts on this subject based on the ideXlab platform.
-
Helmholtz Stereopsis: Exploiting Reciprocity for Surface Reconstruction
International Journal of Computer Vision, 2002Co-Authors: Todd E. Zickler, P.n. Peter N Peter N Belhumeur, David J. KriegmanAbstract:We present a method—termed Helmholtz stereopsis—for reconstructing the geometry of objects from a collection of images. Unlike existing methods for surface reconstruction (e.g., stereo vision, structure from motion, photometric stereopsis), Helmholtz stereopsis makes no assumptions about the nature of the bidirectional reflectance distribution functions (BRDFs) of objects. This new method of multinocular stereopsis exploits Helmholtz reciprocity by choosing pairs of light source and camera positions that guarantee that the ratio of the emitted radiance to the Incident Irradiance is the same for corresponding points in the two images. The method provides direct estimates of both depth and surface normals, and consequently weds the advantages of both conventional stereopsis and photometric stereopsis. Results from our implementation lend empirical support to our technique.
-
ECCV (3) - Helmholtz Stereopsis: Exploiting Reciprocity for Surface Reconstruction
Computer Vision — ECCV 2002, 2002Co-Authors: Todd E. Zickler, P.n. Peter N Peter N Belhumeur, David J. KriegmanAbstract:We present a method - termed Helmholtz stereopsis - for reconstructing the geometry of objects from a collection of images. Unlike most existing methods for surface reconstruction (e.g., stereo vision, structure from motion, photometric stereo), Helmholtz stereopsis makes no assumptions about the nature of the bidirectional reflectance distribution functions (BRDFs) of objects. This new method of multinocular stereopsis exploits Helmholtz reciprocity by choosing pairs of light source and camera positions that guarantee that the ratio of the emitted radiance to the Incident Irradiance is the same for corresponding points in the two images. The method provides direct estimates of both depth and field of surface normals, and consequently weds the advantages of both conventional and photometric stereopsis. Results from our implementations lend empirical support to our technique.
Felix L Figueroa - One of the best experts on this subject based on the ideXlab platform.
-
photoinhibition of photosynthesis in macrocystis pyrifera phaeophyceae chondrus crispus rhodophyceae and ulva lactuca chlorophyceae in outdoor culture systems
Journal of Photochemistry and Photobiology B-biology, 2000Co-Authors: Alejandro Cabellopasini, Eneas Aguirrevonwobeser, Felix L FigueroaAbstract:Abstract The effect of solar radiation on photosynthesis and chlorophyll fluorescence associated to photosystem II (PS II) was determined in the Phaeophyta Macrocystis pyrifera , the Rhodophyta Chondrus crispus and the Chlorophyta Ulva lactuca by oxygen evolution and pulse-amplitude-modulated (PAM) fluorescence. The algae were maintained in 1.2 m 3 outdoor tanks with constant aeration and at 8, 26 and 100% Incident Irradiance ( E o ). All three species showed a decrease in Δ F / F m ′ values during solar noon compared to values in the morning and afternoon, suggesting a photoinhibition of photosynthesis. In general, photoinhibition was negatively correlated to increasing daily Irradiance in all three species. Photoinhibition in C. crispus occurred in tissue incubated at 8, 26 and 100% E o , while in M. pyrifera and U. lactuca a decrease in Δ F / F m ′ values was only observed in tissue incubated at 100% E o . This suggests that species that naturally grow at greater depths might be more susceptible to excessive light when cultured in shallow waters compared to species that naturally inhabit shallower depths. In M. pyrifera , Δ F / F m ′ values were lower in the afternoon than those in the morning, suggesting slower repair mechanisms of the photosystem II compared to the other species. The results suggest that photoinhibition could be reduced by reducing Incident Irradiance to culture systems or increasing of biomass to promote self-shading. Gross oxygenic photosynthesis increased linearly at low electron transport rates after which it saturated in all three species. This suggests that chlorophyll fluorescence could be used as an indicator of the physiological status of macroalgae maintained in dense aquaculture systems.
F. L. Figueroa - One of the best experts on this subject based on the ideXlab platform.
-
Photoinhibition of photosynthesis in Macrocystis pyrifera (Phaeophyceae), Chondrus crispus (Rhodophyceae) and Ulva lactuca (Chlorophyceae) in outdoor culture systems.
Journal of photochemistry and photobiology. B Biology, 2020Co-Authors: A. Cabello-pasini, E Aguirre-von-wobeser, F. L. FigueroaAbstract:The effect of solar radiation on photosynthesis and chlorophyll fluorescence associated to photosystem II (PS II) was determined in the Phaeophyta Macrocystis pyrifera, the Rhodophyta Chondrus crispus and the Chlorophyta Ulva lactuca by oxygen evolution and pulse-amplitude-modulated (PAM) fluorescence. The algae were maintained in 1.2 m3 outdoor tanks with constant aeration and at 8, 26 and 100% Incident Irradiance (E(o)). All three species showed a decrease in deltaF/F'm values during solar noon compared to values in the morning and afternoon, suggesting a photoinhibition of photosynthesis. In general, photoinhibition was negatively correlated to increasing daily Irradiance in all three species. Photoinhibition in C. crispus occurred in tissue incubated at 8, 26 and 100% E(o), while in M. pyrifera and U. lactuca a decrease in deltaF/F'm values was only observed in tissue incubated at 100% E(o). This suggests that species that naturally grow at greater depths might be more susceptible to excessive light when cultured in shallow waters compared to species that naturally inhabit shallower depths. In M. pyrifera, deltaF/F'm values were lower in the afternoon than those in the morning, suggesting slower repair mechanisms of the photosystem II compared to the other species. The results suggest that photoinhibition could be reduced by reducing Incident Irradiance to culture systems or increasing of biomass to promote self-shading. Gross oxygenic photosynthesis increased linearly at low electron transport rates after which it saturated in all three species. This suggests that chlorophyll fluorescence could be used as an indicator of the physiological status of macroalgae maintained in dense aquaculture systems.
-
Daily and seasonal variations of optimum quantum yield and phenolic compounds in Cystoseira tamariscifolia (Phaeophyta)
Marine Biology, 2006Co-Authors: R. T. Abdala-díaz, A. Cabello-pasini, E. Pérez-rodríguez, R. M. Conde Álvarez, F. L. FigueroaAbstract:Effects of solar radiation on phenolic compound concentrations and photosynthetic activity, estimated as in vivo chlorophyll fluorescence, in the brown alga Cystoseira tamariscifolia (Hudson) Papenfuss were analyzed in southern Spain from June 1988 to July 2000. Annual and diurnal variations of optimum quantum yield were negatively correlated with Incident Irradiance. Optimum quantum yield decreased as Irradiance increased at noon, and yield values recovered in the afternoon suggesting a dynamic photoinhibition. The annual and daily fluctuations of phenolic compound concentration in the tissue of C. tamariscifolia showed contrasting patterns. There was an annual cycle of phenolic compound concentration in the apical thallus, which was positively correlated with Incident Irradiance. The increase in phenolic compounds, however, was twofold greater in the first half of the year than the decrease during the second half of the year. In contrast to the annual cycle, there appeared to be a negative correlation between phenolic compound concentration and Irradiance in the summer months while no specific relationship was observed in the fall–winter months. Loss of phenolic compounds from the tissue to the surrounding water was increased as irradiation dosage increased. This suggests that the decrease of phenolic compounds during the diurnal cycle might be regulated by the exudation of these compounds at high Irradiances in the field. Collectively, our results suggest that, like dynamic photoinhibition, the rapid synthesis and turnover time of phenolic compounds in the tissue of C. tamariscifolia might serve as photoprotective mechanisms against high Irradiances.
P.n. Peter N Peter N Belhumeur - One of the best experts on this subject based on the ideXlab platform.
-
Helmholtz Stereopsis: Exploiting Reciprocity for Surface Reconstruction
International Journal of Computer Vision, 2002Co-Authors: Todd E. Zickler, P.n. Peter N Peter N Belhumeur, David J. KriegmanAbstract:We present a method—termed Helmholtz stereopsis—for reconstructing the geometry of objects from a collection of images. Unlike existing methods for surface reconstruction (e.g., stereo vision, structure from motion, photometric stereopsis), Helmholtz stereopsis makes no assumptions about the nature of the bidirectional reflectance distribution functions (BRDFs) of objects. This new method of multinocular stereopsis exploits Helmholtz reciprocity by choosing pairs of light source and camera positions that guarantee that the ratio of the emitted radiance to the Incident Irradiance is the same for corresponding points in the two images. The method provides direct estimates of both depth and surface normals, and consequently weds the advantages of both conventional stereopsis and photometric stereopsis. Results from our implementation lend empirical support to our technique.
-
ECCV (3) - Helmholtz Stereopsis: Exploiting Reciprocity for Surface Reconstruction
Computer Vision — ECCV 2002, 2002Co-Authors: Todd E. Zickler, P.n. Peter N Peter N Belhumeur, David J. KriegmanAbstract:We present a method - termed Helmholtz stereopsis - for reconstructing the geometry of objects from a collection of images. Unlike most existing methods for surface reconstruction (e.g., stereo vision, structure from motion, photometric stereo), Helmholtz stereopsis makes no assumptions about the nature of the bidirectional reflectance distribution functions (BRDFs) of objects. This new method of multinocular stereopsis exploits Helmholtz reciprocity by choosing pairs of light source and camera positions that guarantee that the ratio of the emitted radiance to the Incident Irradiance is the same for corresponding points in the two images. The method provides direct estimates of both depth and field of surface normals, and consequently weds the advantages of both conventional and photometric stereopsis. Results from our implementations lend empirical support to our technique.
