toasty cascade

The cascade operation computes lower-resolution tiles from higher-resolution tiles. The same algorithms apply to either studies or all-sky TOAST pyramids.


toasty cascade
   [--parallelism FACTOR]
   [--format FORMAT]
   {--start DEPTH}

The PYRAMID-DIR argument gives the location of a directory containing tile pyramid data files. The --start DEPTH argument gives the depth at which tiles already exist. For instance, with --start 5, the pyramid should contain level-5 tiles, and the cascade will fill in tiles between levels 4 and 0, inclusive.

Each tile pyramid directory may contain multiple data formats (e.g. PNG, FITS). The --type argument specifies which one the cascade operation should apply to. Valid choices are png, jpg, npy, and fits. The default is to try and determine the format automatically.

The --parallelism FACTOR argument specifies the level of parallism to use. On operating systems that support parallel processing, the default is to use all CPUs. To disable parallel processing, explicitly specify a factor of 1.


Currently, parallel processing is only supported on the Linux operating system, because fork()-based multiprocessing is required. MacOS should support this, but there is currently (as of Python 3.8) a bug preventing that.