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Spherical Harmonic Gradients for Mid-Range Illumination [article]

Thomas Annen, Jan Kautz, Frédo Durand, Hans-Peter Seidel
2004 Symposium on Rendering  
We show that the gradient of the incident-radiance spherical harmonics can be computed for little additional cost compared to the coefficients alone.  ...  Spherical harmonics are often used for compact description of incident radiance in low-frequency but distant lighting environments.  ...  Acknowledgments We would like to thank Paul Debevec for the light probes and Paul Green for proof-reading the paper.  ... 
doi:10.2312/egwr/egsr04/331-336 fatcat:tzqo5icv5zfklgssetu4v5mqkm

Spherical harmonic gradients

Thomas Annen, Jan Kautz, Frédo Durand, Hans-Peter Seidel
2004 ACM SIGGRAPH 2004 Sketches on - SIGGRAPH '04  
For close-and mid-range illumination, the incident radiance does change at every p. Hence, the above distant-illumination assumption is not valid. The point x has a differential solid area dA(x).  ...  This approach permits the illumination of objects with low-frequency incident lighting represented in spherical harmonics [Edm60] .  ... 
doi:10.1145/1186223.1186361 dblp:conf/siggraph/AnnenKDS04 fatcat:7vuq6u2za5aa7lui5n2tu44ssi

Symmetry of illumination and implosion of hotraum targets for heavy ion inertial fusion

M.M Basko
1993 Nuclear Fusion  
Separate one dimensional (1-D) simulations for the pole and equator target sectors indicate that the t = 2 mode in the asymmetry of fuel implosion vanishes for a" = 36".  ...  Meyer-ter-Vehn and the author is analysed in the case when the target is driven by a non-spherical ensemble of heavy ion beams.  ...  Witkowski for providing an opportunity to work at the Max-Planck-Institut fir Quantenoptik. This work was supported by the Deutsche Bundesministerium fiir Forschung und Technologie.  ... 
doi:10.1088/0029-5515/33/4/i08 fatcat:kpcq53ox65fxfjq3al2gzkw4jm

Precomputation-Based Rendering

Ravi Ramamoorthi
2007 Foundations and Trends in Computer Graphics and Vision  
Complex lighting, reflection, shadow and global illumination effects can be rendered with modern image synthesis algorithms, but those methods are focused on offline computation of a single image.  ...  In this survey, we describe the mathematical foundations, history, current research and future directions for precomputation-based rendering.  ...  I started to work on spherical harmonics and real-time rendering during my PhD at Stanford University with Pat Hanrahan, to whom I owe a significant debt.  ... 
doi:10.1561/0600000021 fatcat:lruiwpvi75bevf5ietum5cn33q

Non-contact XUV metrology of Ru/B4C multilayer optics by means of Hartmann wavefront analysis

Mabel Ruiz-Lopez, Hugo Dacasa, Benoit Mahieu, Magali Lozano, Lu Li, Philippe Zeitoun, Davide Bleiner
2018 Applied Optics  
The results showed that the technique detects the aberrations in the nanometer range.  ...  The experiment was carried out in a tabletop laboratory using a high-order harmonic generation as an XUV source.  ...  The multilayer mirror under test is illuminated with a high harmonic beam with a divergence of approximately 2 mrad.  ... 
doi:10.1364/ao.57.001315 pmid:29469828 fatcat:p6exxzwdmzcabjks5fftinklhu

Illumination Processing in Face Recognition [chapter]

Yongping Li, Chao Wang, Xinyu Ao
2010 Face Recognition  
Spherical Harmonics Ravi Ramamoorthi and Pat Hanrahan (Ramamoorthi & Hanrahan, 2001) presented spherical harmonics method.  ...  With the spherical harmonics illumination representation, the illumination coefficients and texture information can be estimated.  ...  Also a broad range of problems is covered: feature extraction and dimensionality reduction (chapters 1-4), 2D face recognition from the point of view of full system proposal (chapters 5-10), illumination  ... 
doi:10.5772/8937 fatcat:75e3tf6sd5ep3byewjbt2tnx4u

ILLUMINATION PROCESSING IN FACE RECOGNITION

ZHENXUE CHEN, CHENGYUN LIU, FALIANG CHANG, XUZHEN HAN, KAIFANG WANG
2014 International journal of pattern recognition and artificial intelligence  
Spherical Harmonics Ravi Ramamoorthi and Pat Hanrahan (Ramamoorthi & Hanrahan, 2001) presented spherical harmonics method.  ...  With the spherical harmonics illumination representation, the illumination coefficients and texture information can be estimated.  ...  Also a broad range of problems is covered: feature extraction and dimensionality reduction (chapters 1-4), 2D face recognition from the point of view of full system proposal (chapters 5-10), illumination  ... 
doi:10.1142/s0218001414560114 fatcat:ifk7ftontzgrdkz4pe7jjdkuoa

TESS Photometric Mapping of a Terrestrial Planet in the Habitable Zone: Detection of Clouds, Oceans, and Continents [article]

Rodrigo Luger, Megan Bedell, Roland Vanderspek, Christopher J. Burke
2019 arXiv   pre-print
Using a spherical harmonic-based reflection model developed as an extension of the STARRY package, we are able to reconstruct the surface features of this rocky world.  ...  We find tentative evidence for variability in Sol d's cloud coverage over the course of Sector 1 observations.  ...  We chose a maximum spherical harmonic degree l max = 10 for our fits.  ... 
arXiv:1903.12182v1 fatcat:bdhtdmcsofcvhn46quu3pbszzi

Requirements for gravity measurements on the anticipated Artemis III mission [article]

Peter James, Anton Ermakov, Michael Sori
2020 arXiv   pre-print
The purpose of this document is to demonstrate the reasoning behind the specific measurement requirements in the white paper by James et al. titled "The value of surface-based gravity and gravity gradient  ...  The induced potential is quantified with the k lm Love numbers, where l is spherical harmonic degree and m is spherical harmonic order.  ...  Again, the tidal response would be purely a function of spherical harmonic degree for simple internal structure models.  ... 
arXiv:2009.03514v1 fatcat:qso27l4iyjed7hsvcwo7x2x7wm

Practical filtering for efficient ray-traced directional occlusion

Kevin Egan, Frédo Durand, Ravi Ramamoorthi
2011 Proceedings of the 2011 SIGGRAPH Asia Conference on - SA '11  
(e) At little extra cost our method can also compute spherical harmonic occlusion for low frequency lighting.  ...  While computing (a) our method also outputs directional occlusion information for 9 spherical harmonic coefficients (green is positive, blue is negative).  ...  We also thank the reviewers for their insightful comments.  ... 
doi:10.1145/2070752.2024214 fatcat:6me2uf5fxnelfpmdp2kjzcwibm

Practical filtering for efficient ray-traced directional occlusion

Kevin Egan, Frédo Durand, Ravi Ramamoorthi
2011 Proceedings of the 2011 SIGGRAPH Asia Conference on - SA '11  
(e) At little extra cost our method can also compute spherical harmonic occlusion for low frequency lighting.  ...  While computing (a) our method also outputs directional occlusion information for 9 spherical harmonic coefficients (green is positive, blue is negative).  ...  We also thank the reviewers for their insightful comments.  ... 
doi:10.1145/2024156.2024214 fatcat:3pfiq2xbsrg7dd2bn5mvh4duc4

Practical filtering for efficient ray-traced directional occlusion

Kevin Egan, Frédo Durand, Ravi Ramamoorthi
2011 ACM Transactions on Graphics  
(e) At little extra cost our method can also compute spherical harmonic occlusion for low frequency lighting.  ...  While computing (a) our method also outputs directional occlusion information for 9 spherical harmonic coefficients (green is positive, blue is negative).  ...  We also thank the reviewers for their insightful comments.  ... 
doi:10.1145/2070781.2024214 fatcat:7ojdth7cebaa7f4shsan4ydlf4

The Horizontal Kinetic Energy Spectrum and Spectral Budget Simulated by a High-Resolution Troposphere–Stratosphere–Mesosphere GCM

John N. Koshyk, Kevin Hamilton
2001 Journal of the Atmospheric Sciences  
The global spectral kinetic energy budget for various height ranges is computed as a function of total horizontal wavenumber.  ...  Tropospheric kinetic energy spectra show the familiar ϳϪ3 power-law dependence on horizontal wavenumber for wavelengths between about 5000 and 500 km and have a slope of ϳϪ5/3 at smaller wavelengths.  ...  spherical harmonics of orders n Ϫ 1 and n ϩ 1.  ... 
doi:10.1175/1520-0469(2001)058<0329:thkesa>2.0.co;2 fatcat:6m77rqwio5bdnowclxefwm6xyy

Dynamics of a vesicle in general flow

J. Deschamps, V. Kantsler, E. Segre, V. Steinberg
2009 Proceedings of the National Academy of Sciences of the United States of America  
The findings are in semiquantitative accord with the recent theory made for a quasi-spherical vesicle, although vesicles with large deviations from spherical shape were studied experimentally.  ...  Another analytical approach based on a quasi-spherical vesicle approximated by a spherical harmonics expansion used a perturbation scheme around the Lamb solution of the Stokes flow near a spherical body  ...  First, the vesicles we observed had large values of ⌬, while the theory was developed for nearly spherical vesicles, i.e., for ⌬Ͻ Ͻ1.  ... 
doi:10.1073/pnas.0902657106 pmid:19553213 pmcid:PMC2710699 fatcat:wrz53myehvdovhc3jr54nodori

Determination of material properties by use of third-harmonic generation microscopy

J. M. Schins, T. Schrama, J. Squier, G. J. Brakenhoff, M. Müller
2002 Journal of the Optical Society of America. B, Optical physics  
to that at the fundamental frequency, and (iii) its thickness and for the identification of a gradient region between two adjacent layers.  ...  Measurements and model calculations have been performed of the third-harmonic yield generated from homogeneous layers.  ...  For all NAs the illumination distribution is close to a hat profile (flat intensity distribution with a hard, circular top), whereas the third-harmonic intensity profile is close to Gaussian.  ... 
doi:10.1364/josab.19.001627 fatcat:tyfeb57duvc3xhkofvf44aobbi
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