Lidar data visualization

Introduction

Use Lidar data, post analyze it with Python/ Pandas? and use Blender to visualize it.

Theory

The free Lidar data set are available e.g. at Opentopography.org. We use both, the Tif data and LAS data of IT-Ren, Fluxnet site

LAS File Format

LAS@Wikipedia how to print lidar file format las

a) Headers.

b) VLR: Variable Length Record. Include 1) header and 2) payload.

c) Point records. Different point formats 0-10.

LAS in Python

To check if the data points are there

[PyLAS Github]

[Laspy Github] [LasPy]

import numpy as np
import pylas

las = pylas.read( fname )
#np.all(las.user_data == las['user_data'])

point_format = las.point_format
print( point_format )
print( point_format.id )
print( list(point_format.dimension_names) )

from mpl_toolkits import mplot3d
import matplotlib.pyplot as plt
fig = plt.figure()
ax = plt.axes(projection='3d')

N=5000
ax.scatter3D(las.X[:N], las.Y[:N], las.Z[:N], c=las.Z[:N], cmap='Greens');

Lidar Cloud Data to Blender Mesh using Opend3D

Blender need mesh, also nodes, faces and vertices. Thus, the data cloud need to be converted to mesh data. We use the Rolling Ball algorithm of Open3d package.

<syntaxhighlight lang="python"> fname = '20150608_it-ren_nadir_densified_point_cloud_merged.las'

import pylas las = pylas.read( fname ) print('Points from data:', len(las.points))

N=100000 N=25797964 X = np.transpose( [las.X[:N], las.Y[:N], las.Z[:N]] ) cloud = o3d.geometry.PointCloud() cloud.points = o3d.utility.Vector3dVector(X)

o3d.visualization.draw_geometries([cloud]) <syntaxhighlight>

how do i convert a 3d point cloud ply into a mesh with faces and vertices

Cloud to Mesh Tutorial

Interpolate lidar

Render data in Blender

Rendering cloud data in Blender