UNDERSTANDING AVAILABLESOURCES OF SURVEY DATA

AND ITS APPLICATION

presented by

Sr. Muhammad Firhat bin Hamidun MISMMember of the Institution of Surveyors Malaysia

OFFICENO.18 & 18-1, JALAN PPS 2, PUSAT PERDAGANGAN SELASEH, 68100 BATU CAVES, SELANGOR.

TEL: 03-61783872/5874 FAX: 03-61782873 E-MAIL: fh6@yahoo.com

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Type of Available Data

Space BorneAirborneLand Survey, GPSHandheld Scanned Detection – RD, GPRHydrographicArchived – topographical sheets, Std Sheets, CP

Space Borne

Data Gathered Using Satellite Radar Sat. False color – Looking for Radiometric

Differential Parameters Imagery LatSAT 2.5m, 5.0m , IKONOS 0.72m ,

QuickBird 0.6m Space Shuttle SRTM (Shuttle Radar Topographic

Mission ) ASTER ( Advanced Spaceborne Thermal Emission and

Reflection Radiometer)

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Imagery

IKONOS Imagery Accuracy Findings on Stereo Pairs

QuickBird Imagery Accuracy Findings on Stereo Pairs

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SRTM

The Shuttle Radar Topography Mission (SRTM) is an international research effort that obtained digital elevation models on a near-global scale from 56° S to 60° N,[2] to generate the most complete high-resolution digital topographic database of Earth prior to the release of the ASTER GDEM in 2009.SRTM consisted of a specially modified radar system that flew on board the Space Shuttle Endeavour during the 11-day STS-99 mission in February 2000, based on the older Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR), previously used on the Shuttle in 1994. To acquire topographic (elevation) data, the SRTM payload was outfitted with two radar antennas.[2] One antenna was located in the Shuttle's payload bay, the other – a critical change from the SIR-C/X-SAR, allowing single-pass interferometry – on the end of a 60-meter (200-foot) mast[2] that extended from the payload bay once the Shuttle was in space. The technique employed is known as Interferometric Synthetic Aperture Radar.

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Airborne

Airborne Laser Mapping – Laser Range Finder incorporated with High Resolution Digital Camera System

IFSAR – Interferrometric Synthetic Aperture Radar Aerial Photogrammetry – being superceded by digital camera technology incorporated with

Laser Mapping System UAV Mapping systems

Land Survey

Conventional Survey with Total Station and Level GPS

Geodetic Control / Static / Fast Static MyRTKNet system with MyGeoid – need cellular coverage Kinematic GPS Realtime systems eg. OmniStar

Utilities Mapping / Geological Study

Radio Detection ( RD ) conductive and metallic GPR ( Ground Penetrating Radar ) - Ground Scanner

Utilities Pavement Integrity Study Geological Study

Magnetic Locator – metallic and conductive

Hydrographic Survey

near shore (< 3km from shoreline ) or depth upto 30m – single frequency Echosounder offshore ( > 3km from shoreline ) or depths more than 30m – dual frequency Echosounder with

Sound Velocity Meter for calibration

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USES OF SATELLITE IMAGES

Satellite image data offer significant capabilities for deriving information integral to human dimensions studies, especially those concerned with the impacts of human activity on land use and land cover. These data inherently contain information that relates to the type and spatial extent of land cover. Major techniques for deriving information from satellite images include 1) Image Interpretation; 2) Digital

Image Classification; 3) Data Transformations; and 4) Change Detection. The information output of these operations may be useful as a final product or can be entered into a geographic information system (GIS) for subsequent integrated analysis and/or model development with other spatial variables.

Wikipedia's suggests that Satellite images have many applications in agriculture, geology, forestry, biodiversity conservation, regional planning, education, intelligence and warfare. Images canbe in visible colours and in other spectra. There are also elevation maps, usually made by radar imaging. Interpretation and analysis of satellite imagery is conducted using software packages like ERDAS

Imagine or ENVI. Some of the first image enhancement of satellite photos was conducted by the U.S. Government and its contractors. For example ESL Incorporated developed some of the earliest two dimensionalFourier transforms applied to digital image processing to address NASA photos as well as national security applications. Satellite imagery is also used in seismology and oceanography in deducing changes to land formation, water depth and sea bed, by color caused by earthquakes, volcanoes, and tsunamis.

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Airborne Laser Mapping

accuracy of data gathered depends on the components and survey control parameters

Components rate of laser pulse per seconds speed of aircraft height of aircraft distance between aircraft and GPS ground control point rate of correction for pitch, roll and heading

Limitations normally cannot penetrate cloud normally cannot penetrate water bodies cannot penetrate very thick canopy – eg. Dense forest or

thick undergrowth ( lallang ) Needs ground team to verify details and under bridges,

culverts etc Need ground team to establish calibration pads in area of

interest

The absolute accuracy of the elevation data is 15 centimeters; relative accuracy can be less than 5 cm. Absolute accuracy of the XY data is dependent on operating parameters such as flight altitude,but accuracy in the range of tens of centimeters to one meter can usually be achieved. The elevation data is generated at thousands of points per second, resulting in elevation point densities far greater than traditional ground survey methods. One hour of data collection can result in over 10,000,000 individually geo-referenced elevation points. With these high sampling rates, it is possible to rapidly complete a large topographic survey and still generate DTMs with a grid spacing of one meter or less.

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COORDINATES AND DATUMS

Coordinates

Most heard-off in Malaysia Cassini – for Standard Sheets, Certified Plans and PT

Lots. Used to be non-metric scale. Being converted

MRSO / BRSO – Topographical sheets and Cadastral in Sabah Sarawak but topographical only in Semenanjung Malaysia

WGS84 Newly derived GDM2000

GDM stands for the Geocentric Datum of Malaysia. It forms the newearth-centred coordinate datum for Malaysia that will ‘gradually’ replace the regional datums of Kertau 1948 in Peninsular Malaysia and Timbalai 1948 in Sabah and Sarawak. GDM2000 is basically realized using Global Positioning System (GPS) to connect the national Zero Order Network (i.e. the Malaysia Active GPS System stations) with some of the global permanent GPS network (i.e. the International GPS Service stations). GDM2000 was officially

launched on 26th of August 2003.

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Datums

LSD ( Land Survey Datum ) ACD ( Admiralty Chart Datum ) MyGeoid

The Malaysian geoid project (MyGEOID) is unique where the whole country is covered by with dense airborne gravity with the aim to make the best possible national geoid model

Land Survey Datum

It is used for engineering project. Usually used the vertical datum from established BM. LSD is differing from MSL because reduced level from

established BM is referring to MSL at Klang Port. Reduced sounding refer to LSD can merge with land details

refer to vertical datum from established BM.

Chart Datum

Mean sea level is the average of high tide and low tide. It is used to determine the elevation of objects on land.

Admiralty chart datum is "mean low water", that is, the averageof all LOW tides. For navigation, that's what you want, becauseyou don't want to run your ship onto any reefs.

Theoretically this should not change with time, although global warming is currently raising sea level by about 3mm per year worldwide. So it's likely that at some time in the future, these standards (along with their maps and charts) will be revised.

The difference between MSL and chart datum varies from placeto place, because different places have different tides.

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Quality Assurance

Cross checks between different surveyorsIndependent Site Surveys eg 100m x 100m at selected locationsDistance calibrationAngle calibrationLevel CalibrationGPS calibration

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SAMPLES

LandSAT

Ikonos

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QuickBird

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LIDAR ACQUISITION SYSTEM

Airborne Laser Meassurement Parameters

Airborne Laser Digital Surface Model

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Karak Town Laser Point Cloud

Isometric View of Karak Town

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Cross Section Extraction

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DESIRED DATA/LIDAR SYSTEM SPECIFICATIONS ?

Laser repetition rate 33 – 167 kHz

Operating altitude 80 – 4,000 m (higher altitude optional )

Horizontal accuracy 1/11,000 x altitude; + 1 sigma

Elevation accuracy 5 – 10 cm typical + 1 sigma

Range capture Up to range measurements for each pulse, including last ?OR40,000 points per second or greater

Intensity capture 4 intensity reading with 12 bit dynamic range for each measurement

Scan frequency Variable to 100Hz

Scan angle Variable from 0 to + 25 deg, in increment of 1 deg

Spot distribution Saw tooth, uniform spot spacing across 96% of scan

Scanner products Scan angle x scan frequency < 1000

Roll compensation 5Hz update rate(Scan angle + roll comp. Angle = 30”, eg + 20” scan allows+10” compensation )

Swath width Variable from 0 to 0.93 x altitude (m)

Beam divergence nominal( 1/e full angle )

Dual divergence 0.15/0.25 mrad or 0.80 mrad

Data storage Ruggerdized removeable media

Position orientation system Appalanix – POS/AV including internal 12 channel dual frequency 10 Hz GPS receiver ORKinematic On-The-Fly (OTF) GPS solution plus the use of laser pulsesof suitable wavelength

Laser classification Class IV ( FDA 21 CFR )

Density level Not less than (1 point / 1m sq)

Do you really understand the above jargon?Did you know that there are more superior system available?

BUT, you know what you want. Why not specify YOUR requirements?

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ACTUALLY, WHAT IS LIDAR ?

I want a vehicle.

IF THE ABOVE ARE CLASSIFIED AS VEHICLES, YOU WILL CHOOSE ACCORDING TO YOUR REQUIREMENT, NOT BECAUSE OF PRICE, LOOKS AND SPECIFICATIONS.

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DATA REQUIREMENT SPECIFICATIONS

USER OF DATA KNOWS WHAT THEY WANT THE DATA TO BE USED FOR.

SPECIFY YOUR REQUIREMENT, NOT THE METHOD OF DATA CAPTURE.

REQUEST FOR QA/QC PROCEDURE TO ENSURE DATA INTEGRITY

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UNDERGROUND SCANNING

Ground Penetrating Radar – Noggin SmartCart System

Sample GPR Data Along Railway Track

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Sample GPR Data for Pavement Integrity Study

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THANK YOU FOR YOUR ATTENTION

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