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DTM by M. Varshosaz. An introduction to DTM. Overview of your syllabus Definition Applications Overview of DTM tasks Generation Manipulation Interpretation Visualizations. Definition:. - PowerPoint PPT Presentation
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Digital Terrain Models by M. Varshosaz
1 DTM by M. VarshosazDTM by M. Varshosaz
Digital Terrain Models by M. Varshosaz
2
Digital Terrain Models by M. Varshosaz
3 An introduction to DTMAn introduction to DTM
Overview of your syllabus Definition Applications Overview of DTM tasks
Generation Manipulation Interpretation Visualizations
Digital Terrain Models by M. Varshosaz
4 Definition:Definition:
A statistical representation of the continuous surface of the ground by a large number of selected points with known X, Y, and Z coordinates in an arbitrary co-ordinate field.
Provide the means for representing the continuous surface in a digital form using a finite amount of storage.
Provide the means for representing the earth’s surface in the computer.
Digital Terrain Models by M. Varshosaz
5 TerminologyTerminology
Digital Terrain Model (DTM). Digital Elevation Model (DEM). Digital Height Model (DHM). Digital Ground Model (DGM). Digital Terrain Elevation Data
(DTED). Digital Surface Model (DSM).
Digital Terrain Models by M. Varshosaz
6 TerminologyTerminology
DEM (Digital Elevation Model): Generally refers to a regular array of elevations
(squares or hexagon). The term is in widespread use in the USA.
DHM (Digital Height Model): Similar as DEM but less commonly used. The term originated in Germany.
DGM (Digital Ground Model): More emphasis on the digital model of the
solid/continuous surface of the earth. The term in is general use in the UK.
Digital Terrain Models by M. Varshosaz
7 Terminology (cont.)Terminology (cont.)
DTM (Digital Terrain Model): More complex concept involving elevations and
other GIS features (e.g., rivers, ridges, break lines, etc.).
It encompasses terrain relief, planimetric, and derived data (slope, aspect, visibility, etc.).
DTED (Digital Terrain Elevation Data): Term used by the US National Imaging and
Mapping Agency (NIMA) formerly known as the Defense Mapping Agency (DMA).
Usually refers to girded/regular arrays.
Digital Terrain Models by M. Varshosaz
8 Terminology (cont.)Terminology (cont.)
DSM (Digital Surface Model): The previous terms usually refer to
bare terrain models. DSM refers to digital models including
features above the surface of the earth (e.g., buildings).
Very important for ortho-photo generation.
Digital Terrain Models by M. Varshosaz
9 DTM synonyms: DTM synonyms: conclusionconclusion
Most widely used are DTM and DEM To define a DTM need:
A number of sample points which can define earth with a given degree of accuracy (DATA)
A mathematical model filling the gaps between the sample points
Data and model (MODEL) Data and model stored and worked in digital
Digital Terrain Models by M. Varshosaz
10 DEM productsDEM products
Slope angle Slope aspect Slope convexity Slope length Hillshading 3D display
Digital Terrain Models by M. Varshosaz
11 DTM Application DTM Application DomainsDomains
Civil Engineering: Cut-and-fill problems involved with road
design. Site planning. Volumetric calculations in building dams
and reservoirs.
Digital Terrain Models by M. Varshosaz
12
(Rail) Road design(Rail) Road design
Horizontal alignment
Digital Terrain Models by M. Varshosaz
13
Conventional (rail)road Conventional (rail)road designdesign
Longitudinal Profile
(vertical alignment)
Digital Terrain Models by M. Varshosaz
14
Cross Sections
cut & fill volumes
Concept of
Conventional (rail)road Conventional (rail)road designdesign
Digital Terrain Models by M. Varshosaz
15
SCOP
(Rail)road design with (Rail)road design with DTMDTM
Digital Terrain Models by M. Varshosaz
16 DTM Application DTM Application domains (cont.)domains (cont.)
Earth Sciences: Drainage basin network development
and delineation. Hydrological run-off modeling. Geo-morphological simulation and
classification. Geological mapping. Generating slope and aspect maps.
Digital Terrain Models by M. Varshosaz
17 Applications of DTM Applications of DTM (cont.)(cont.)
Analysis and interpretation of terrain morphology
A vertical view of a computed drainage system
Digital Terrain Models by M. Varshosaz
18 DTM Application DomainsDTM Application Domains
Planning and Resource Management: The management of natural resources. Site location. Support of image classification in
remote sensing by DTM derivatives. Geometric and radiometric correction of
remote sensing images Wind flow and pollution dispersion
models.
Digital Terrain Models by M. Varshosaz
19
Monitoring waste deposits Monitoring waste deposits comparing volumes under comparing volumes under DTM in different timesDTM in different times
100 m
Digital Terrain Models by M. Varshosaz
20 DTM Application DTM Application DomainsDomains
Military Applications: Consumers and producers (e.g., NIMA). End objectives are very specialised and demanding. Inter-visibility analysis for battlefield management. 3-dimensional display for weapons guidance systems and
flight simulation. Radar line-of-sight analyses.
Topographic mapping. Surveying and Photogrammetry:
They are important sources for DTM generation. DTMs are useful for various surveying and
photogrammetric activities: Ortho-photo production, Data quality assessment, and
Digital Terrain Models by M. Varshosaz
21 Applications of DTM Applications of DTM (cont.)(cont.)
Military service 3D visualization
and Flight simulation
Intervisibility analysis
Weapon guidance etc
Digital Terrain Models by M. Varshosaz
22 DTM application areas DTM application areas (cont.)(cont.) Surveying and photogrammetry
Orthophoto production Topographic mapping
Digital Terrain Models by M. Varshosaz
23 What about GIS?What about GIS?
DTM used as base map similar to 2D DTM is 2.5D since includes third
dimension (Z) depending on (X,Y)
H stored as an attribute H stored s a function of (X,Y)
Digital Terrain Models by M. Varshosaz
24 Elements of Digital Terrain Elements of Digital Terrain ModelingModeling
Tasks involved in DTM production and use.
Digital Terrain Models by M. Varshosaz
25 DTM tasks: generationDTM tasks: generation
Buy global or national data set Collect data
Digital Terrain Models by M. Varshosaz
26
Buy global or national data Buy global or national data setset
Digital Terrain Models by M. Varshosaz
27 Examples Topographic Examples Topographic DataData
(*) completed[Eidenbenz et al, 1997]
Examples: 3 ENMAs
Current products Production method
Current activity
OS (GB)
Paper maps 1:1250, 1:2500 2D database ( 1:1250 , 1:2500 ) National DTM ( 1:10k,1:50k)
Road centreline DB
Photogrammetry Map digitizing (*) Map digitizing (*)
DB updating by A.Ph. & monoplot.
Contours updating by A.Photogr.
IGN (F)
Paper maps 1:25,50,100,250 k 2D database (acc. 10m) 2.5D database (acc. 2m) National DTM Road DB
Map digitizing (*) Photogrammetry Map digitizing (*)
Data collection by A.Ph. & D.Ph. Develop prod. line for image matching Develop prod.line for auto road extrac.
SFOT (CH)
Paper maps 25, 50, 100k 2D database (acc. 5m) ( 1:25k)
National DTM ( 1:25,000 )
Photogr. (*) Map digitizing (*) Map digitizing (*)
Map revision Prepare for upgrading to 2.5D Develop prod. line for auto AT Develop prod. line for digital OP from auto AT and national DTM
NCC Paper maps (1/10,000 , 1/25,000 ) DTM of some states (1/25,000 )
Photogrammetry Production/Revision
Digital Terrain Models by M. Varshosaz
28 Data captureData capture
Data acquisition techniques Surveying Photogrammetry and Remote Sensing Laser ranging Using current topographic maps
Model construction Interpolation techniques
Digital Terrain Models by M. Varshosaz
29 DTM tasks: DTM tasks: manipulationmanipulation
Modification and refinement of DTMs, and derivation of intermediate models. This might include: Editing: correcting errors and updating DTMs. Filtering: smoothing, enhancing, compression
and Resampling. Merging and Joining DTMs: combining DTMs
from several sources (possibly at different epochs).
Converting DTM from one data structure to another: for example: TIN to grid conversion.
Digital Terrain Models by M. Varshosaz
30 DTM tasks: DTM tasks: interpretationinterpretation
Extraction of terrain related attributes and features through quantitative analysis
Geomorphometric analysis DTM quality assessment
Error detection Quality control
Planning and engineering applications Visibility analysis
Digital Terrain Models by M. Varshosaz
31 DTM tasks: visualizationDTM tasks: visualization
Orthographic techniques
Contours Hill shading Combination with
2D data Perspective
techniques Block diagrams 3D perspective Virtual Fly
Digital Terrain Models by M. Varshosaz
32 Your feedback Your feedback
Through your reports, term papers, critics
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