clipping.rst

Cliping data with polygons

Purpose:

• Subset data with a polygon
• Assign attribute data
• Use PDAL pipeline

:ref:`Clipping Workshop Materials <unavco:clipping>`

Clipping (Autzen)

Clipping (setup)

• Polygons as GeoJSON
• Data in two coordinate system
• First use of PDAL Pipeline

Clipping (polygon)

Clipping (reproject)

• GeoJSON in Geographic
• LiDAR in State Plane
• Use OGR VRT

Clipping (vrt)

.. literalinclude:: ../../exercises/analysis/clipping/attributes.vrt
    :linenos:

Clipping (pipeline)

• translate not expressive enough
• Complex operations (merge, filter, write)
• Repeatable operations with substitution

Clipping (pipeline)

.. literalinclude:: ../../exercises/analysis/clipping/clipping.json
    :linenos:

Pipeline

1. :ref:`readers.las`
2. :ref:`filters.overlay`
3. :ref:`filters.range`
4. :ref:`writers.las`

Attribute Filter

• Assign point values
  • Polygon
  • Single value

Range Filter

• Keep or reject values

Pipeline Strategy

1. Assign with filters.overlay
2. Filter with filters.range

Clipping (command)

.. literalinclude:: ../../exercises/analysis/clipping/clipping-run-command.txt
    :linenos:

Clipping (verify)

Next

On to :ref:`colorization`