Approximate Visibility Grids for Interactive Indirect Illumination

Author(s):  
Thomas Bashford-Rogers ◽  
Kurt Debattista ◽  
Carlo Harvey ◽  
Alan Chalmers
1931 ◽  
Vol 4 (6) ◽  
pp. 559-564 ◽  
Author(s):  
Wallace A. Thomson

A method is described by which illumination intensities were measured by a photo-electric cell and galvanometer, and a continuous photographic record obtained of the variations of intensity over a period of time during which the ground was covered with snow.It was found that a remarkable increase in the illumination was caused by the presence of cloudiness with full sunshine. The percentage increase due to this condition in many cases was 20–30%, and on one occasion it was as high as 40%.When there was a cloud over the sun, with most of the sky clear, the decrease in illumination was found to vary up to 35%, depending on the density of the cloud, and on many occasions it was observed that the increase in indirect illumination due to overhead cloudiness more than balanced the decrease of direct illumination when the sun was partly hidden. From this it is concluded that the intensity may be greater with the sun partly hidden than at the same time of day with a clear sky.


2019 ◽  
Vol 38 (7) ◽  
pp. 449-460
Author(s):  
Takahiro Kuge ◽  
Tatsuya Yatagawa ◽  
Shigeo Morishima

2008 ◽  
Vol 27 (5) ◽  
pp. 1-8 ◽  
Author(s):  
T. Ritschel ◽  
T. Grosch ◽  
M. H. Kim ◽  
H.-P. Seidel ◽  
C. Dachsbacher ◽  
...  

Author(s):  
Everett Lawson ◽  
Jason Boggess ◽  
Siddharth Khullar ◽  
Alex Olwal ◽  
Gordon Wetzstein ◽  
...  

Author(s):  
Yujia Zhang ◽  
Alper Yilmaz

Surface reconstruction using coded structured light is considered one of the most reliable techniques for high-quality 3D scanning. With a calibrated projector-camera stereo system, a light pattern is projected onto the scene and imaged by the camera. Correspondences between projected and recovered patterns are computed in the decoding process, which is used to generate 3D point cloud of the surface. However, the indirect illumination effects on the surface, such as subsurface scattering and interreflections, will raise the difficulties in reconstruction. In this paper, we apply maximum min-SW gray code to reduce the indirect illumination effects of the specular surface. We also analysis the errors when comparing the maximum min-SW gray code and the conventional gray code, which justifies that the maximum min-SW gray code has significant superiority to reduce the indirect illumination effects. To achieve sub-pixel accuracy, we project high frequency sinusoidal patterns onto the scene simultaneously. But for specular surface, the high frequency patterns are susceptible to decoding errors. Incorrect decoding of high frequency patterns will result in a loss of depth resolution. Our method to resolve this problem is combining the low frequency maximum min-SW gray code and the high frequency phase shifting code, which achieves dense 3D reconstruction for specular surface. Our contributions include: (i) A complete setup of the structured light based 3D scanning system; (ii) A novel combination technique of the maximum min-SW gray code and phase shifting code. First, phase shifting decoding with sub-pixel accuracy. Then, the maximum min-SW gray code is used to resolve the ambiguity resolution. According to the experimental results and data analysis, our structured light based 3D scanning system enables high quality dense reconstruction of scenes with a small number of images. Qualitative and quantitative comparisons are performed to extract the advantages of our new combined coding method.


1995 ◽  
Vol 29 (Supplement) ◽  
pp. 61-66
Author(s):  
Takashi KUNITANI ◽  
Hisashi SATO ◽  
Kunio KONDO ◽  
Shisuo SHIMADA

2021 ◽  
Author(s):  
Tina Hollandt ◽  
Markus Baur ◽  
Caroline Wöhr

AbstractConsidering animal welfare, animals should be kept in animal-appropriate and stress-free housing conditions in all circumstances. To assure such conditions, not only basic needs must be met, but also possibilities must be provided that allow animals in captive care to express all species-typical behaviors. Rack housing systems for snakes have become increasingly popular and are widely used; however, from an animal welfare perspective, they are no alternative to furnished terrariums. In this study, we therefore evaluated two types of housing systems for ball pythons (Python regius) by considering the welfare aspect animal behavior. In Part 1 of the study, ball pythons (n = 35) were housed individually in a conventional rack system. The pythons were provided with a hiding place and a water bowl, temperature control was automatic, and the lighting in the room served as indirect illumination. In Part 2 of the study, the same ball pythons, after at least 8 weeks, were housed individually in furnished terrariums. The size of each terrarium was correlated with the body length of each python. The terrariums contained substrate, a hiding place, possibilities for climbing, a water basin for bathing, an elevated basking spot, and living plants. The temperature was controlled automatically, and illumination was provided by a fluorescent tube and a UV lamp. The shown behavior spectrum differed significantly between the two housing systems (p < 0.05). The four behaviors basking, climbing, burrowing, and bathing could only be expressed in the terrarium. Abnormal behaviors that could indicate stereotypies were almost exclusively seen in the rack system. The results show that the housing of ball pythons in a rack system leads to a considerable restriction in species-typical behaviors; thus, the rack system does not meet the requirements for animal-appropriate housing.


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