LSD PQSL Series 2014 Topographical Surveying and Utility Survyeing

Transcription

1 LSD PQSL Series 2014 Topographical Surveying and Utility Survyeing NG Wai-tak, Victor 18 May 2015

2 Objective Help LSD probationers to prepare for the LSD APC Part I Written Assessment to be held on 13 June LSD APC Part I Written Assessment Date: 13 June 2015 (Saturday) Time: 10:00 am to 12:00 noon Venue: Hong Kong Management Association Room 201, 2/F, First Commercial Building Leighton Road, Causeway Bay Application Deadline: No later than 5:30pm on 15 May 2015 (Friday)

3 Cadastral Surveying Engineering Surveying Photogrammetry and Remote Sensing Topographical Surveying Geographic Information System Utility Surveying Mapping and Cartography Hydrographic Surveying Geodetic Surveying

4 Topographical Surveying Mapping standards and specifications Map updating and change detection Map projection and datum Data collection methods Spatial data management Data integration and alignment Map drawing and presentation

5 Topographical Surveying What is Topographical Survey? to measure the world to map the world So how is the our world?

6 Topographical Surveying Characteristic of the world is three dimensional complex (with overlapping features) covered (with dense vegetation)

7 Topographical Surveying

8 Topographical Surveying Source: GeoInfoMap (

9 Topographical Surveying Source: Explanatory Notes on Geodetic Datums in Hong Kong (SMO, LandsD)

10 Topographical Surveying Data Quality Survey Method Mapping Specifications CAD Standard for Works Projects (CSWP) Drafting Specifications for Engineering Survey (Nov 2014) Others Data Alignment Measures (DAM)

11 Data Quality Model Completeness: commission and omission Logical consistency: conceptual consistency; domain consistency; format consistency; topological consistency Positional accuracy: external accuracy and internal accuracy for both horizontal and vertical accuracy Thematic accuracy: classification correctness

12 Utility Surveying Project management and engineering practice Detail and as-built surveys Buried object positioning methodology Visualisation and Modelling Data interpretation and analysis Data management and retrieval Utility related legislations Site safety and management

13 Utility Surveying What is Utility Surveying? to survey the location of underground utility to survey the condition of underground utility Characteristic of Utility Surveying Unseen but exist Could be very complicated Uncertainty

14 Utility Surveying

15 Utility Surveying an emerging profession in Hong Kong and worldwide. underground utility s spider networks : water supply drainage Sewerage Power Gas Telecommunication pipes and cables

16 Utility Surveying from above ground to characterization of underground or subsurface. increasing awareness of tragedies e.g. landslide which happened in Kwun Lung Lau on 23 July 1994, triggered by constant water seepage due to defective drainage network buried in the slope.

17 Utility Surveying Statutory requirements Gas Safety Ordinance CAP 51B Electricity Supply Lines (Protection) Regulation CAP 406 H

18 Utility Surveying Ground Penetration Radar (GPR) Pipe Cable Location (PCL) Leak Noise Correlator (LNC) CCTV Infrared thermography Gas Leak Detector Visual Inspection Trial Pit

19 Ground Penetration Radar (GPR) Post-acquisition Processing and Interpretation Gain recovery Filtering F-k modeling Modeling Migration Straitigraphic interpretation Time slices Source: Guide to GRP Survey for Detection of Underground Utilities - HKIUS

20 Ground Penetration Radar (GPR) Migration Correct structural placement of dipping events Focus diffractions caused by point scattering centres and subsurface fault bounds Correct amplitudes for geometric focusing effects and spatial smearing Sorting out of crossing events like those produced by sharp synclines Improvement in resolution Source: Guide to GRP Survey for Detection of Underground Utilities - HKIUS

21 THANK YOU