..  _reference.focal:

*****
Focal
*****

.. caution::

   Focal operations use ``dask.array.map_overlap``.  Each chunk dimension
   must be **larger than the kernel depth** (typically 1 cell for a 3x3
   kernel).  Chunks smaller than the depth produce wrong results.

.. note::

   ``mean`` and ``focal_stats`` output **float32**; ``hotspots`` outputs
   **int8** confidence bands. Both ``mean`` and ``hotspots`` exclude NaN
   neighbours from their neighbourhood computation.

Apply
=====
.. autosummary::
   :toctree: _autosummary

   xrspatial.focal.apply

Hotspots
========
.. autosummary::
   :toctree: _autosummary

   xrspatial.focal.hotspots

Mean
====
.. autosummary::
   :toctree: _autosummary

   xrspatial.focal.mean

Bilateral
=========
.. autosummary::
   :toctree: _autosummary

   xrspatial.bilateral.bilateral


GLCM Texture
=============
.. autosummary::
   :toctree: _autosummary

   xrspatial.glcm.glcm_texture


Edge Detection
==============
.. autosummary::
   :toctree: _autosummary

   xrspatial.edge_detection.sobel_x
   xrspatial.edge_detection.sobel_y
   xrspatial.edge_detection.laplacian
   xrspatial.edge_detection.prewitt_x
   xrspatial.edge_detection.prewitt_y


Focal Statistics
================
.. autosummary::
   :toctree: _autosummary

   xrspatial.convolution.convolution_2d
   xrspatial.convolution.annulus_kernel
   xrspatial.convolution.calc_cellsize
   xrspatial.convolution.circle_kernel
   xrspatial.focal.custom_kernel
   xrspatial.focal.focal_stats