【点云无损压缩】python-pcl:点云las、laz文件的读取、写入、压缩
2023-09-27 14:26:27 时间
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 File
def 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
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 os
def 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 pylas
def 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!
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