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==================
Examples
==================
Filtering
---------
This example shows how you can extract points from a file and write them into a new one.
We use the classification field to filter points, but this can work with the other fields.
.. code-block:: python
import laspy
las = laspy.read('tests/data/simple.las')
new_file = laspy.create(point_format=las.header.point_format, file_version=las.header.version)
new_file.points = las.points[las.classification == 1]
new_file.write('extracted_points.las')
Creating from scratch
---------------------
There are multiple ways to create new las files.
Creating a new LasData
______________________
.. code-block:: python
import laspy
import numpy as np
# 0. Creating some dummy data
my_data_xx, my_data_yy = np.meshgrid(np.linspace(-20, 20, 15), np.linspace(-20, 20, 15))
my_data_zz = my_data_xx ** 2 + 0.25 * my_data_yy ** 2
my_data = np.hstack((my_data_xx.reshape((-1, 1)), my_data_yy.reshape((-1, 1)), my_data_zz.reshape((-1, 1))))
# 1. Create a new header
header = laspy.LasHeader(point_format=3, version="1.2")
header.add_extra_dim(laspy.ExtraBytesParams(name="random", type=np.int32))
header.offsets = np.min(my_data, axis=0)
header.scales = np.array([0.1, 0.1, 0.1])
# 2. Create a Las
las = laspy.LasData(header)
las.x = my_data[:, 0]
las.y = my_data[:, 1]
las.z = my_data[:, 2]
las.random = np.random.randint(-1503, 6546, len(las.points), np.int32)
las.write("new_file.las")
Using LasWriter
_______________
.. code-block:: python
import laspy
import numpy as np
# 0. Creating some dummy data
my_data_xx, my_data_yy = np.meshgrid(np.linspace(-20, 20, 15), np.linspace(-20, 20, 15))
my_data_zz = my_data_xx ** 2 + 0.25 * my_data_yy ** 2
my_data = np.hstack((my_data_xx.reshape((-1, 1)), my_data_yy.reshape((-1, 1)), my_data_zz.reshape((-1, 1))))
# 1. Create a new header
header = laspy.LasHeader(point_format=3, version="1.2")
header.offsets = np.min(my_data, axis=0)
header.scales = np.array([0.1, 0.1, 0.1])
# 3. Create a LasWriter and a point record, then write it
with laspy.open("somepath.las", mode="w", header=header) as writer:
point_record = laspy.ScaleAwarePointRecord.zeros(my_data.shape[0], header=header)
point_record.x = my_data[:, 0]
point_record.y = my_data[:, 1]
point_record.z = my_data[:, 2]
writer.write_points(point_record)
Using chunked reading & writing
-------------------------------
This example shows how to use the 'chunked' reading and writing feature
to split potentially large LAS/LAZ file into multiple smaller file.
.. literalinclude:: ../examples/recursive-split.py
:language: Python
COPC
----
.. literalinclude:: ../examples/copc.py
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