Pelatihan :

Techniques in Active Tectonic StudyJuni 20-Juli 2, 2013

Instruktur: Prof. J Ramon Arrowsmith (JRA)Dari Arizona State University (ASU) - US

Tempat Pelaksanaan: Ruang Pangea, Laboratorium Gempabumi (LabEarth) –

Puslit Geoteknologi LIPI dan Kuliah lapangan akan dilakukan disekitar Sesar Lembang, Jawa Barat.

* Lebih jelas baca TOR/KAK dan daftar acara

High resolution topography exercise and discussion

Airborne Laser Swath Mapping (ALSM)

1 5 - 2 0 c m

D irec tio n o f

F lig h t

G P S R e fe re n c eB a se S ta tio n

Laser

L ase r P u lseL ase r

S p o t S ize

S can L in e

1. Laser scanner

2. Inertial Measureme

nt Unit (IMU)

3. GPS

-Phillips, UNAVCO

R. Haugerud, U.S.G.S

D. Harding, NASA

Answer science question

Gridded productsGeodesy and signal processing

Point Cloudxn, yn, zn, in

ALSM workflow:

Survey->Process->Classify->Interpolate/Grid->Analyze

Ecology Applications:

• 3D vegetation information & interactions between vegetation and topography

• 3D vegetation structure:

– estimation of stand height

– total aboveground biomass

– foliage biomass

– basal area

– tree density,

– canopy base height

– canopy bulk density

Stoker et al., 2006

Comparisons of Techniques for measuring surfaces and detecting changes in surfaces*

GPS InSAR ALSM TLSSample

Density

1 site/10 km2 10,000 pixels/ km2

1-10 hits/ m2 1000 hits/ m2

Position

Precision

1-20 mm 2-3 m 5-15 cm 0.6-5 cm

Change

Detection

1 mm 1-2 cm 10 cm 1 cm

Scale Global 100 km 10-100 Km 1 km

* Ball park numbers for typical applications

-Phillips, Meertens, and Jackson, UNAVCO

• x,y,z + attributes

• Filtering algorithms allow classification by return type:– Ground, vegetation, building …

LiDAR “point cloud”

Digital Elevation Models• Digital representation of

topography / terrain– “Raster” format – a grid of

squares or “pixels”– Continuous surface where Z

(elevation) is estimated on a regular X,Y grid

– “2.5D”

• Grid resolution is defined by the size in the horizontal dimension of the pixel– 1 meter DEM has pixels 1 m x 1m assigned a single

elevation value.

Source: http://www.ncgia.ucsb.edu/giscc/extra/e001/e001.html

• 1 meter grid

• LiDAR returns from EarthScope data collection

• Example from flat area with little or no vegetation so ground is sampled approx. 5+ times per square meter

• How do we best fit a continuous surface to these points?

• Ultimately wish to represent irregularly sampled data on a regularized grid.

1 meter1

met

er

Facilitate community access to high-resolution, Earth science-oriented, topography data, and related tools and resources.

http://www.opentopography.org

Let’s tour OpenTopography

http://rapidlasso.com/