Add option to convolve all generated images/cubes to the same resolution

caracal-pipeline / caracal

Containerized Automated Radio Astronomy Calibration (CARACal) pipeline

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Add option to convolve all generated images/cubes to the same resolution #779

Open gigjozsa opened 4 years ago

gigjozsa commented 4 years ago

If the images/cubes do not have the same resolution mosaicing is problematic (which is sortafn understatement). So we need an option to convolve all cubes or images to the same resolution posteriori in the selfcal and image_line workers. Alternatively, this could be done in the mosaic worker, but my preference would be imaging.

gigjozsa commented 4 years ago

Could we discuss if this may become a requirement for the release?

o-smirnov commented 4 years ago

@landmanbester implemented this (and more) here: https://github.com/ska-sa/codex-africanus/issues/176

gigjozsa commented 4 years ago

Make a histogram of all beam HPBWs (there is one per plane) multiplied by frequency (normalized to lowest frequency F0)
- Select the largest value HPBWt at 2 sigma off the median (one can also attempt to choose the median)
- For each plane convolve to a resolution HPWBt*f0/f by FFT-convolving with an appropriate HPBW along the minor and major axes:
  - Create Gaussian cube with circular HPBW = HPWBt*f0/f for each plane
  - FFT that cube, result Gt_fft
  - Create Gaussian cube with central beam(s) derived from cube HPBWs and PAs per plane
  - FFT that cube, result Go_fft
  - FFT the data cube, result I_fft
  - calculate I_fft x Go_fft / Gt_fft = It_fft
  - Inverse-FFT that data cube

gigjozsa commented 4 years ago

Notice that we may also have a 1/F option in this.

svw26 commented 4 years ago

Yup, see https://github.com/caracal-pipeline/caracal/issues/862#issuecomment-610308433

And I'd like to highlight the 'mirto' label that had been added to this issue... Please could we make it Amarula instead? Much more consistent in quality ;) x

francescaLoi commented 10 months ago

Images and cubes convolution is possibile with the polimager worker. I am still working on it, the branch is called polimager but it only works with a Stimela branch made by @Mulan-94. She added the spimple tool by Landman. @Mulan-94 did you merge that branch on the master version of Stimela?