Fine Deformation Monitoring of Ancient Building based on Terrestrial Laser Scanning Technologies Zhou Wei Key Laboratory of Digital Earth, Institute of.

Fine Deformation Monitoring of Ancient Building

based on Terrestrial Laser Scanning Technologies

Zhou WeiKey Laboratory of Digital Earth, Institute of Remote Sensing and Digital

Earth (RADI), Chinese Academy of Sciences;

International Centre on Space Technologies for Natural and Cultural Heritage (HIST), under the Auspices of UNESCO

23 April 2013

Outline

• Introduction

• Data Acquisition & Processing

• Deformation Monitoring

• 3-Dimensional Modeling

• 3D Information Management System

Research Background

World Heritage

Impact on

Land encroachment

Pollution

……

Human Induced

Uncontrolled Tourism

Resource over-exploitation

Deformation

Meteorological Disasters (Storm)

Forest Disasters (Forest Fire)

……

Natural Influence

Floods & Ocean Disasters (Tsunamis)

Global Change (Greenhouse Effect)

Geohazards (Earthquake)

Solution

General Objective

Fine Mapping & Historical Info

Monitoring & Analyzing

Evaluation & Early Warning

Documentation

Restoration

Publicity

PreventativeProtection

SmartManagement

Space Technologies play an important role in the sustainable development of world heritage!

The Summer Palace, located in a northwestern suburb of Beijing, first built in 1750, largely destroyed in the war of 1860 and restored on its original foundations in 1886 – is a masterpiece of Chinese landscape garden design. It is also presently the best-preserved imperial garden.It was inscripted in the World Heritage List in 1998.

Experimental Site – World Cultural Heritage

Quickbird Imagery of the Summer PalaceAcquired on 22 Mar 2009

Longevity Hill

Kunming Lake

West Lake

17-Arch Bridge

South Island

South Lake

Tower of Buddhist Inscense

As the symbol of the Summer Palace, the Tower of Buddhist Incense represents the highest achievement of traditional Chinese architectural art.

The octagonal, three-storied and quadruple-eaves wood-constructed tower is built on a 20-metre-high granite platform with the Longevity Hill in the north and the Kunming Lake in the south. There’re eight solid lignumvitae columns served as pillars supporting the 36.47-metre-high tower.

the Tower of Buddhist Incense

Due to disrepair, natural disasters, climate change and human activities, the tower is facing great threats.

glazed roof tilesroof ridge animals

Ironstand added to the ancient buildingThreaten the Authenticity!

wooden pillars damaged by the pests

Threaten the Integrity!

Threats to the Tower

Outline

• Introduction

• Data Acquisition & Processing

• Deformation Monitoring

• 3-Dimensional Modeling

• 3D Information Management System

Apparatus Parameter

Ambiguity interval 79 m

Min. range 0.4 m

Resolution range 0.1 mm

Max. data acquisition rate 1 016 727 pxl/sec.

Z+F IMAGER 5006i

Terrestrial Laser Scanning Apparatus

Leica ScanStation C10

Apparatus Parameter

Ambiguity interval 300 m

Min. range 0.1m

Resolution range 6 mm

Max. data acquisition rate 50 000 pxl/sec.

obtain relative long-range data

obtain close-range dataHandheld 3D Scanner

obtain data of single cultural relic or areas cannot reached by the above two scanners

3rd storey and the interlayer above it Long-range scanning for

the whole tower

Data Acquisition by Laser Scanning

1st storey 2nd storey on the scaffold and indoor

white points are the artificial targets

Point Clouds Registration

Due to complicated objects overlapping caused by observing from different points of view and the geometric characteristics of the object itself, it’s hard to obtain complete information of a certain target just from one scan station. The solution is to use the same group of artificial targets which are placed in the scene and measured from each of the overlapping scan stations.

indoor point clouds of the 1st storey

registration result of the 1st storey

registration result of the 3 stories

registration result of the whole tower and its surroundings

Point Clouds Registration

In order to improving the registration precision, 92 scan stations were set up for data acquisition. Moreover, some more artificial targets are placed to increase redundant observations.

The registration error of point cloud data is less than 5 millimetres.

Produce CAD Drawings

the slices

of point

clouds

CAD drawings

we get many cross-sections in each storey, and then each cross-sections can outline structural feature of building.

The elevations of the Tower of Buddhist Incense

The sections of the Tower of Buddhist Incense

Produce CAD drawings

Outline

• Introduction

• Data Acquisition & Processing

• Deformation Monitoring

• 3-Dimensional Modeling

• 3D Information Management System

In order to estimate the dip and dip direction of every pillar, we get the cross-sections from the top and the bottom part of the pillar segment in each storey, and then eight cross-sections can be obtained from one integral pillar including the pillar segment inside the double eaves above the third storey.

Cross-Section of the Pillars

Estimate Dip & Dip Direction

cross sections of the pillars’ bottom in each story

The tower has a slight inclination towards the southeast, and the dip

angle is around 0.7 degree.

dip direction of the Pillars Dip angle of the Pillars

the dip and dip direction of every pillar can be worked out by connecting the centre points of each pillar

Estimate Dip & Dip Direction

Outline

• Introduction

• Data Acquisition & Processing

• Deformation Monitoring

• 3-Dimensional Modeling

• 3D Information Management System

Pre-maintenance Under repair After-maintenance

we must record the status quo and history information elaborately and comprehensively. Laser scanning technologies are applied to 3D model building of the tower, and the detail property of the tower components can be recorded based on 3D models.

The Tower of Buddhist Incense has been repaired every few years.

3D Modeling

Roof ridge animal scanned by handheld 3D scanners the lion's model

Eaves scanned by Z+F laser scanners the model of eaves

3D Modeling

3d model of the paintingstexture capture & point clouds of paintings in the 3rd storey

point clouds capture of the xumi support model of the xumi support

3D Modeling

Rendered 3D Model of the Whole Tower

Outline

• Introduction

• Data Acquisition & Processing

• Deformation Monitoring

• 3-Dimensional Modeling

• 3D Information Management System

It turns out that building the database of 3D models and picture archives help to preserve the original data of cultural heritage, including the spatial relationship information and other important types of data.

3D Information Management System

The tower has a complicated structure, so the 3D models of the tower are divided into three stories to manage, and the same kind of components is put in a category in a single storey.

3D Information Management System

maintenance organization

maintenance record

maintenance time

dialog box of component maintenance information

3D Information Management System

shooting time of photo of the tower components

Pre-maintenance

Under repair

After-maintenance

dialog box of component maintenance information

3D Information Management System

Video DisplayFinally

Thank you！