| RDB 2

rdb-example-04-update-points.py
1 #!/usr/bin/env python3
2 # -*- coding: utf-8 -*-
3 #
4 #*******************************************************************************
5 #
6 # Copyright 2025 RIEGL Laser Measurement Systems
7 #
8 # Licensed under the Apache License, Version 2.0 (the "License");
9 # you may not use this file except in compliance with the License.
10 # You may obtain a copy of the License at
11 #
12 # http://www.apache.org/licenses/LICENSE-2.0
13 #
14 # Unless required by applicable law or agreed to in writing, software
15 # distributed under the License is distributed on an "AS IS" BASIS,
16 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17 # See the License for the specific language governing permissions and
18 # limitations under the License.
19 #
20 # SPDX-License-Identifier: Apache-2.0
21 #
22 #*******************************************************************************
23 #
24 """
25 rdb-example-04-update-points.py
26
27 This example shows how to open an existing database and modify some points.
28 This example is based on the database of rdb-example-1-create-database.
29 """
30
31 import riegl.rdb
32
33 # Access existing database
34 with riegl.rdb.rdb_open("pointcloud.rdbx") as rdb:
35
36 # Before we can modify the database, we must start a transaction
37 with riegl.rdb.Transaction(
38 rdb, # point cloud object
39 "Update", # transaction title
40 "Point Classifier v1.0" # software name
41 ) as transaction:
42
43 # Prepare point attribute buffers
44 buffer_size = 10000 # point block/chunk size
45 buffer_point_number = riegl.rdb.AttributeBuffer(
46 rdb.point_attributes["riegl.id"], buffer_size
47 )
48 buffer_point_class = riegl.rdb.AttributeBuffer(
49 rdb.point_attributes["riegl.class"], buffer_size
50 )
51
52 # Start new select query to get point id of points with reflectance
53 # below -20 dB
54 with rdb.select("riegl.reflectance < -20.0") as select:
55 select.bind(buffer_point_number)
56
57 # Start new update query and define buffers
58 with rdb.update() as update:
59 update.bind(buffer_point_number)
60 update.bind(buffer_point_class)
61
62 # Process all points block-wise
63 point_count = 1 # actual number of points not yet known
64 while point_count > 0:
65 point_count = select.next(buffer_size)
66
67 # Define new point class
68 for i in range(point_count):
69 buffer_point_class[i] = 7
70
71 # Actually update points
72 update.next(point_count)
73
74 # Finally commit transaction
75 transaction.commit()