Volume 532, August 2011
|Number of page(s)||8|
|Section||Numerical methods and codes|
|Published online||19 July 2011|
ARKCoS: artifact-suppressed accelerated radial kernel convolution on the sphere
Institut d’Astrophysique de Paris, UMR 7095, CNRS – Université Pierre et Marie Curie (Univ Paris 06), 98 bis blvd Arago, 75014 Paris, France
2 Departments of Physics and Astronomy, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
Received: 25 March 2011
Accepted: 7 June 2011
We describe a hybrid Fourier/direct space convolution algorithm for compact radial (azimuthally symmetric) kernels on the sphere. For high resolution maps covering a large fraction of the sky, our implementation takes advantage of the inexpensive massive parallelism afforded by consumer graphics processing units (GPUs). Its applications include modeling of instrumental beam shapes in terms of compact kernels, computation of fine-scale wavelet transformations, and optimal filtering for the detection of point sources. Our algorithm works for any pixelization where pixels are grouped into isolatitude rings. Even for kernels that are not bandwidth-limited, ringing features are completely absent on an ECP grid. We demonstrate that they can be highly suppressed on the popular HEALPix pixelization, for which we develop a freely available implementation of the algorithm. As an example application, we show that running on a high-end consumer graphics card our method speeds up beam convolution for simulations of a characteristic Planck high frequency instrument channel by two orders of magnitude compared to the commonly used HEALPix implementation on one CPU core, while typically maintaining a fractional RMS accuracy of about 1 part in 105.
Key words: methods: data analysis / methods: numerical / techniques: image processing / cosmic background radiation
© ESO, 2011
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