Dong Guangyan, BS, Senior Engineer

Outline  1. Summary  2. Basic principle & typical specifications  3. Comparison with traditional surveying technologies  4. Application status  5. Advantages & disadvantages  6. Expectations

1. Summary  A fire-new technical approach  Single point manually collecting data continuously & automatically acquire batch data  Two types---airborne and ground (according to difference of platforms) satellite borne

2. Basic principle and specifications of typical instrument Target Interface Post- processing Signal processing Transmitter Receiver Figure 1 Principle sketch map of 3D laser surveying system The hardcore is a 3D laser scanner ， which mainly consists of the laser transmitter, receiver, scanning system and bracket system ， meanwhile, it integrates with CCD digital camera and internal calibration systems as well.

 Non-contact, high speed laser measurement mode  Acquiring 3D data of terrain and array geometry of surface of complicated object with point cloud.  TOF (Time of Flight) pulse ranging method  Approach to calculation of 3D laser spot coordinate for pulse ranging method Basic principle

Calculation expressions ： S α Z Y P(Xs,Ys,Zs) θ X Figure 2 Spatial coordinate system of 3D laser surveying system Basic principle

Typical instrument  Optech ILRIS-36D Capture Every Dimension

Typical instrument  Leica HDS3000

Typical instrument  Mensi GX RD 200 +

Main specifications of typical instrument ManufacturerOptechLeicaMensi ProductsILRIS-36DHDS3000GX RD200+ Laser SecurityClass nmClass 3Class 3 532nm Ranging Single point point Positioning point Range (min.)1.5m1m Range( max.)1500,1000,800 80% 40% 20% 2600m for DR 200m-90% 350m Scan angle of view110°V×360°H270°V×360°H60°V×360°H Built-in digital camera 6 million pixels1 million pixels 24°×24° 111 pictures Integrative color camera 5.5 × optical zooming Postprocessing softwarePolyworks/InspectorCycloneRealworks Modeling precision3mm2mm

3. Comparison with traditional surveying technologies  Different requirements for measurement accuracy and ambients  Different raw data patching format  Different data combined modes among the sites  Different build modes for TIN models  Different extract modes for grains

4. Application status  3D laser scanning system can rapidly rebuild a 3D solid model of an object.  3D laser point cloud data can also use the complete target data for post processing(such as ： mapping, computation, stress analysis, finite element analysis, simulation analysis, mission analysis, ⋯ etc.)  It is a symmetric application of all kinds of forward engineering tools (e.g. ： CATIA, UG, CAD, PDMS, PDS, GIS, VR, 3DSMAX, MAYA, ERP, etc.)

4. Application status Generate data image by surveying a target’s 3D coordinate ， then process the data to extract 3D information and generate ： a ） Digital elevation model DEM with high accuracy, contour map and orthograph ； b ） 3D solid image of buildings ； c ） Urban 3D diorama ； d ） Height of trees, vegetation

4. Application status Figure 3 Image of 3D laser surveying system

4. Application status Figure 4 Buildings extracted from Figure 3

4. Application status Fields covered ： cultural relic, archaeology, architectonics, spaceflight, aviation, shipping, manufacture, military industries, military, petrifaction, medicine, water conservancy, energy sources, electric power, traffic, machinery, movies & TV, education, scientific research, automobile, public security, city construction ⋯⋯

Application  Historical Preservation

Application  Historical Preservation

Application  Urban Planning

Application  Urban Planning

Application  Industrial Survey

5. Advantages & disadvantages  Advantages ： High speed ， complete measurement, accurate ， multi- angle-of-view observation ； Non-contact measurement ， all-weather ； Shape measurement for completed surfaced object ， color revivification ； Mark and measure relative model data, such as range, altitude difference, volume, surface area, section, 2D picture etc. Build all kinds of geometry shape ， such as elbow, taper tube etc. Convert 3D model into data format of CAD system or different software operating platforms for 3D modeling.

Advantages example  With point cloud of intensity information ， it will support output to CAD environment for editing and analysis.

Advantages example  The point cloud figure with RGB information can revert the environmental information.

 Disadvantages and challenges ： 3D laser scanner is a black box system ， it is hard to calibrate ； Current instrument are still not perfect in miniaturization and price ， and they are top grade equipment in market ； Longer processing time after data scan ； The scan data patch soft wares are not perfect (lack of compatibility) 。 5. Advantages & disadvantages

 Disadvantages and challenges Lack of consideration of standardization ， Lack of soft wares both practical and lower price ； It is hard to use the fruits of 3D modeling for further speciality research ； 3D modeling has certain subjectivity ， and the laypeople usually visually are puzzled by virtual cartoon ， surveyablity and science of 3D model is ignored. 5. Advantages & disadvantages

6. Expectations Future works ： ● Unification of term ● Establish data standard for accuracy requirement ● Data collection and post-processing requirements ● Approach to fruit accuracy assessment

3D laser scanning technique has unexampled advantages in 3D data rapid acquirement and build 3D model. It is prospective with further effort.

Thanks!