ARKCoS: artifact-suppressed accelerated radial kernel convolution on the sphere
Abstract
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.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- August 2011
- DOI:
- 10.1051/0004-6361/201116963
- arXiv:
- arXiv:1104.0672
- Bibcode:
- 2011A&A...532A..35E
- Keywords:
-
- methods: data analysis;
- methods: numerical;
- techniques: image processing;
- cosmic background radiation;
- Astrophysics - Instrumentation and Methods for Astrophysics;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 10 pages, 6 figures. Submitted to Astronomy and Astrophysics. Replaced to match published version. Code can be downloaded at https://github.com/elsner/arkcos