快速上手点云数据模型_云数据库 RDS(RDS)-阿里云帮助中心

点云数据通常是由3D扫描仪扫描资料并以点的形式输出的记录，每一个点包含有三维坐标，有些可能含有颜色信息（RGB）或反射强度信息（Intensity），点云数据含有空间坐标信息，且具有数量众多、属性维度复杂的特点。

概述

Ganos PointCloud是对象关系型数据库PostgreSQL的一个扩展，使PostgreSQL能够有效快速存储和管理点云数据，并提供点云数据压缩、解压缩、属性统计等功能，同时联合Ganos Geometry模块提供点云空间分析的能力。

点云数据类型

点云数据类型主要分为两种，一种是pcpoint数据类型，一个点一行记录存储。点的维度信息在元数据中定义。另一种是pcpatch数据类型，该类型将点以集合的方式进行存储，支持压缩，减少存储空间，支持空间检索。压缩方式由元数据中的“compression”决定。

点云元数据

表pointcloud_formats记录了点云的schema（元数据）信息。元数据包括点云的属性维度，以及每个维度的数据大小、类型、名称以及解释说明等。

快速入门

创建扩展

Create extension ganos_pointcloud with schema public cascade;
Create extension ganos_pointcloud_geometry with schema public cascade;

插入点云schema

INSERT INTO pointcloud_formats (pcid, srid, schema) VALUES (1, 4326,
'<?xml version="1.0" encoding="UTF-8"?>
<pc:PointCloudSchema xmlns:pc="http://example.org/schemas/PC/1.1"
    xmlns:xsi="http://www.example.org/2001/XMLSchema-instance">
  <pc:dimension>
    <pc:position>1</pc:position>
    <pc:size>4</pc:size>
    <pc:description>X coordinate as a long integer. You must use the
                    scale and offset information of the header to
                    determine the double value.</pc:description>
    <pc:name>X</pc:name>
    <pc:interpretation>int32_t</pc:interpretation>
    <pc:scale>0.01</pc:scale>
  </pc:dimension>
  <pc:dimension>
    <pc:position>2</pc:position>
    <pc:size>4</pc:size>
    <pc:description>Y coordinate as a long integer. You must use the
                    scale and offset information of the header to
                    determine the double value.</pc:description>
    <pc:name>Y</pc:name>
    <pc:interpretation>int32_t</pc:interpretation>
    <pc:scale>0.01</pc:scale>
  </pc:dimension>
  <pc:dimension>
    <pc:position>3</pc:position>
    <pc:size>4</pc:size>
    <pc:description>Z coordinate as a long integer. You must use the
                    scale and offset information of the header to
                    determine the double value.</pc:description>
    <pc:name>Z</pc:name>
    <pc:interpretation>int32_t</pc:interpretation>
    <pc:scale>0.01</pc:scale>
  </pc:dimension>
  <pc:dimension>
    <pc:position>4</pc:position>
    <pc:size>2</pc:size>
    <pc:description>The intensity value is the integer representation
                    of the pulse return magnitude. This value is optional
                    and system specific. However, it should always be
                    included if available.</pc:description>
    <pc:name>Intensity</pc:name>
    <pc:interpretation>uint16_t</pc:interpretation>
    <pc:scale>1</pc:scale>
  </pc:dimension>
  <pc:metadata>
    <Metadata name="compression">dimensional</Metadata>
  </pc:metadata>
</pc:PointCloudSchema>');

创建点云表

-- 使用pcpoint数据类型
CREATE TABLE points (
    id SERIAL PRIMARY KEY,
    pt PCPOINT(1)
);

-- 使用pcpatch数据类型
CREATE TABLE patches (
    id SERIAL PRIMARY KEY,
    pa PCPATCH(1)
);

插入pcpoint类型数据

INSERT INTO points (pt)
SELECT ST_MakePoint(1, ARRAY[x,y,z,intensity])
FROM (
  SELECT
  -127+a/100.0 AS x,
    45+a/100.0 AS y,
         1.0*a AS z,
          a/10 AS intensity
  FROM generate_series(1,100) AS a
) AS values;

SELECT ST_MakePoint(1, ARRAY[-127, 45, 124.0, 4.0]);
-------------------------
010100000064CEFFFF94110000703000000400

SELECT ST_AsText('010100000064CEFFFF94110000703000000400'::pcpoint);
-------------------------
{"pcid":1,"pt":[-127,45,124,4]}

插入pcpatch类型数据

INSERT INTO patches (pa)
SELECT ST_Patch(pt) FROM points GROUP BY id/10;

SELECT ST_AsText(ST_MakePatch(1, ARRAY[-126.99,45.01,1,0, -126.98,45.02,2,0, -126.97,45.03,3,0]));
-------------------------
{"pcid":1,"pts":[
 [-126.99,45.01,1,0],[-126.98,45.02,2,0],[-126.97,45.03,3,0]
]}

pcpatch属性平均值计算

SELECT ST_AsText(ST_PatchAvg(pa)) FROM patches WHERE id = 7;
-------------------------
{"pcid":1,"pt":[-126.46,45.54,54.5,5]}

删除扩展

Drop extension ganos_pointcloud_geometry;
Drop extension ganos_pointcloud cascade;

SQL参考

详细SQL手册请参见 PointCloud SQL参考。