python 点云las、laz文件的读取、写入、压缩

1. python las读取与写入

用laspy库： https://pypi.org/project/laspy/

获取las、laz的规格、点数据格式，点数据的具体字段名称，具体的点数据
解析las、laz头文件区、点数据区的所有字段

参考：https://readthedocs.org/projects/laspy/
参考：https://pylas.readthedocs.io/en/latest/installation.html

pip install laspy

from laspy.file import Filedef main():f = File("E:/dataTes/1001140020191217.las", mode='r')# 查看点云的点格式及字段名称print('\nPoint Of Data Format: ', f.header.data_format_id)print("\tExamining Point Format: ", end=" ")for spec in f.point_format:print(spec.name, end=", ")print('\noffset: ', f.header.offset)  # 偏移量print('scale: ', f.header.scale)  # 比例因子print('min: ', f.header.min)  # x、y、z 的最小值print('max: ', f.header.max)  # x、y、z 的最大值print('file_signature: ', f.header.file_signature)  # 文件标识print('Point Of Data Format: ', f.header.data_format_id)  # 点格式print('data_record_length: ', f.header.data_record_length)  # 点个数print('FileCreateDay+Year: ', f.header.date)print()print('f.x: ', f.x)print('f.y: ', f.y)print('f.z: ', f.z)print('f.intensity: ', f.intensity)print('f.gps_time: ', f.gps_time)print('f.raw_classification: ', f.raw_classification)print()# print('f.user_data: ', f.user_data)# print('f.flag_byte: ', f.flag_byte)# print('f.Color: ', f.red, f.green, f.blue)# print('file_source_id: ', f.header.file_source_id)# print('Major_Minor version: ', f.header.version, str(f.header.version_major) + '.' + str(f.header.version_minor))# print('Generation Software: ', f.header.software_id)# print('system_id: ', f.header.system_id)# print('Header Size: ', f.header.header_size)# print('file_global_encoding: ', f.header.global_encoding)# print('gps_time_type: ', f.header.gps_time_type)# print('guid: ', f.header.guid)print()# print('f.edge_flight_line: ', f.edge_flight_line)# print('f.return_num: ', f.return_num)# print('f.classification: ', f.classification)# print('f.scan_angle_rank: ', f.scan_angle_rank)# print('f.scan_dir_flag: ', f.scan_dir_flag)# print('f.num_returns: ', f.num_returns)# print('pt_src_id: ', f.pt_src_id)f.close()if __name__ == "__main__":main()

2. las的压缩，.las转.laz，.laz转.las

las点云的无损压缩：将.las转为.laz，压缩率可达15%，空间占用减少85%；

需要俩个模块

pip install pylas
pip install lazrs

参考：https://gis.stackexchange.com/questions/332366/reading-laz-file-in-python-directly
pylas官方文档： https://pylas.readthedocs.io/en/latest/installation.html

import pylas
import time# laz 转 las
end0 = time.time()
las = pylas.read('E:/dataTes/1001117.laz')
las = pylas.convert(las)
las.write('E:/dataTes/1001117_laz2las.las')
end1 = time.time()
print("laz2las 耗时:%.2f秒" % (end1 - end0))
print('------------end1------------')# las 转 laz
las1 = pylas.read('E:/dataTes/1001147.las')
las1 = pylas.convert(las1)
las1.write('E:/dataTes/1001147_las2laz.laz')
end2 = time.time()
print("las2laz 耗时:%.2f秒" % (end2 - end1))
print('---------end----------')

3. laspy读取.laz

参考：https://stackoverflow.com/questions/49500149/laspy-cannot-find-laszip-when-is-installed-from-source-laszip-is-in-path

有用到（lasTools的laszip.exe以及dll）
windows下需要往Path环境变量里添加自己下载的lasTools的bin目录；
lasTools下载: https://github.com/m-schuetz/LAStools

from laspy.file import File
import osdef main():# 最重要的后边要有 E:\Las\LAStools\bin; lasTools中laszip.exe的路径print(os.environ["PATH"])# E:\python\lib\site-packages\pywin32_system32;C:\Program Files (x86)\Common Files\Oracle\Java\javapath;C:\ProgramData\Oracle\Java\javapath;D:\jdk181\bin;D:\hadoop-common-2.2.0\bin;C:\Windows\vrv\common\vSSLFltSvc;D:\apache-maven-3.5.3\bin;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\WINDOWS\System32\WindowsPowerShell\v1.0\;C:\WINDOWS\System32\OpenSSH\;D:\dnProject\scala-2.11.8\scala-2.11.8\bin;D:\svnSsrver\bin;D:\apache-maven-3.5.3\bin;E:\PCL 1.8.1\bin;E:\PCL 1.8.1\3rdParty\OpenNI2\Tools;E:\PCL 1.8.1\3rdParty\VTK\bin;E:\python\Scripts\;E:\python\;C:\Users\sunmeina\AppData\Local\Microsoft\WindowsApps;E:\PCL 1.8.1\bin;C:\Users\sunmeina\AppData\Local\BypassRuntm;E:\cmake\bin;E:\python\lib\site-packages\numpy\.libs;E:\Las\LAStools\bin;f = File("E:/dataTes/1001140020191217_las2laz.laz", mode='r')# 查看点云的点格式及字段名称print('\nPoint Of Data Format: ', f.header.data_format_id)print("\tExamining Point Format: ", end=" ")for spec in f.point_format:print(spec.name, end=", ")print('\noffset: ', f.header.offset)  # 偏移量print('scale: ', f.header.scale)  # 比例因子print('min: ', f.header.min)  # x、y、z 的最小值print('max: ', f.header.max)  # x、y、z 的最大值print('file_signature: ', f.header.file_signature)  # 文件标识print('Point Of Data Format: ', f.header.data_format_id)  # 点格式print('data_record_length: ', f.header.data_record_length)  # 点个数print('FileCreateDay+Year: ', f.header.date)print()print('f.x: ', f.x)print('f.y: ', f.y)print('f.z: ', f.z)print('f.intensity: ', f.intensity)print('f.gps_time: ', f.gps_time)print('f.raw_classification: ', f.raw_classification)print()f.close()if __name__ == "__main__":main()

4. pylas读取.laz

import pylasdef lazread(path):print('\n\n------------\n\n')laz = pylas.read(path)print(laz)print(laz.header)print(laz.point_format)print(laz.header.version)print(laz.point_format.id)print(laz.header.file_signature)print('offset: ', laz.header.offset_to_point_data)print('version_major: ', laz.header.version_major)print('version_minor: ', laz.header.version_minor)print('point_count: ', laz.header.point_count)print('legacy_point_count: ', laz.header.legacy_point_count)print('file_source_id: ', laz.header.file_source_id)print('global_encoding: ', laz.header.global_encoding)print('date: ', laz.header.date)print('data_record_length: ', laz.points_data.point_size)print('point_size: ', laz.header.point_size)print('point_data_record_length: ', laz.header.point_data_record_length)print('uuid: ', laz.header.uuid)print('are_points_compressed: ', laz.header.are_points_compressed)print('offset: ', laz.header.offsets)print('scale: ', laz.header.scales)print('min: ', laz.header.mins)print('max: ', laz.header.maxs)print('-------\n')print(laz.point_format.dimension_names)print('laz.x: ', laz.x)print('laz.y: ', laz.y)print('laz.z: ', laz.z)print('laz.intensity: ', laz.intensity)print('laz.gps_time: ', laz.gps_time)print('laz.points: ', laz.points)print('laz.points_data: ', laz.points_data)print(laz.points_data.point_format.id)print(laz.points_data.array)print(laz.points_data.point_size)def main():lazread('E:/Las/1001217_las2laz.laz')print('-------------endl-----------')if __name__ == "__main__":main()

以上测试均在windows10中进行，都ok
centos服务器上方式2中读取laz方式的可以支持；方式3中的不支持，报错如下：

raise ValueError(“Unable to read compressed file!”) ValueError: Unable to read compressed file!