WS 1 - Workshop 1 Quality Management for Geodata
Bernd Aschofftechnet GmbH, Berlin
Commission: FIG Commission 3, 5 and 7
FIG Congress 2006 Munich
Geometrical Improvement of Geodata„Positional Accuracy Improvement“
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• Short introduction to technet• Geometrical deficiencies • Geometrical updating
Topic Overview
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Introduction
Berlin + Stuttgart
technet GmbHgründig + partner
since 1989
Ingineering company:Software development Project consulting
Scopes:Engineering surveying (railways) Cadastral surveyingCivil engineering (leightweight structures)Photogrammetry (close range)
Central Reference:Adjustment
for geometrical optimizations
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Introduction
Net adjustment and track optimizationfor planning and support of the German
Rails (Deutsche Bahn AG)
Engineering SurveyingRail-Software
Adjusting adaptation of track elements (Actually the changeover to the UTM/ETRS89 reference frame)
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Introduction
Formfinding, statical analysis, cutting pattern generation
and volume adjustment for tent roofs
Lightweight Structures
Proximity fitting of graphical geodata following the Membrane Method
large scaled geometrical geodata improvement
Idea for
Allianz ArenaMunich
Hadj pilgrims accomodation „tent city“ inMina Valley (Mekka, Saudi Arabia)
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Stressles coordinates Integrative analysis information
Geodetic measurements
Vectorized Cadastre maps
Cadastral field books
Utility geodata with constraints
Introduction
Geodata source examples
Adjustment delivers:
Orthophotos
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A well known adjustment model.. X = ([AtPA]-1 At P) L
with A = f (X) Non-linear equations (in general)
X0 ... Approximations for unknowns neccesary A1 = f (X0) X1 = ([A1
tPA1]-1 A1tP ) L
A2 = f (X1)X2 = ([A2
tPA2]-1 A2tP ) L
....
Introduction
Iteration process
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Introduction
„Data-Snooping“ parameter of the adjustment:
Statistical Analysis
= ?
Normalized redidual NV
with
vi .... residual of the observation
mvi .... standard deviation of the residual
„apples and pears are comparable“
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Introduction
Landesbetrieb für Geoinformation und Vermessung Hamburg
Transformation of existing Gauß-Krüger- und Soldner systems into the
UTM / ETRS89 system
Interconnected transformation and
proximity fitting
Project extension up to 250.000 points
Proximity fitting
„Graphical“ coordinates with high input accuracy
Project example 1:
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Point database
Digital map database
Residuals
Introduction
Integration of the point database and the digital map database (ALK in lower saxony)
Geometrical quality improvement of the German Automated real estate map (ALK)
Integration of geometrical constraints
and measurements
Project example 2:
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Geometrical deficiencies
Differences between cadastre map and orthophoto
Map and orthophoto do not fit together
Deficiency example 1:
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Differences between point list and field book evidence
Field book numbers were (and are mostly still) not used consequently for coordinates calculation
Geometrical deficiencies
Deficiency example 2:
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Geometrical deficiencies
Deficiency example 3:
Points have different input accuracies
Differences in the German ALK: point database and graphical database
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Geometrical deficiencies
First of all...
Topological disordance• Identical points between datasets - cannot be detected - are wrongly connected
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Point connection types:
Point identity
Same point number (point ID)
Observation type „Point Identity“
• can be modeled stochastically
• can be directly modeled
• is very suitable for automation
Geometrical deficiencies
The role of point topology
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Geometrical deficiencies
Type differences• Archived and actual terrestrial measurements are relative observations which highly consider neighbourhood relations but follow global error propagation - cadastral measurements as well as - old point reference net measurements• GPS observations are (compared to the above) absolute measurements
Accuracy differences• Measurements have relevant accuracy differences - Map measures up to several meters - Geodetic measures from some millimeters up to several decimeters
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Geometrical deficiencies
What is to be done?
Alternative 1• Throw away all relative measures• Only accept GPS measures• Transform graphical geodata exclusively on the base of GPS measured or other old pointsIs this possible as the cadastral evidence is legally binding?
Alternative 2• Integrate legally binding measures with GPS measures• Connect graphical data with the integrated and improved point coordinates
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Geometrical updating
Measurements
redundant(equivocal)
uncorrelatd
Relative geometryPrimary data
Software engineerSurveyor
$Two different expert views
to geodata
Absolute geometry
Coordinates
unique
correlated
Surveyor
Primary data
Software engineer
Adjustment
?Coordinates view
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Geometrical updating
Straight line constraintsRectangle constraintsParallel constraints
Circle measures Orthogonal offsetsLocal coordinatesDistances
28.37
35.2221.46
17.12
12.14
7.88
4.76
10.95Membrane triangles
- 14.36 - - 20.08 -
Artificial and existing observations
Artificial:
Existing:
Utility data
Cadastre data
Point identities
16.72
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Intial situation Proximity fitting
Geometrical updating
Test example
Helmert transformationwithout constraintsProximity fitting with constraintsInitial situation
Comparison:
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Technical steps to eliminate geometrical deficiencies• Extensive connection of geodata sets
• Introduction of artificial relative measures
(membrane triangles, constraints)
• Introduction of existing measurements
• Adjustment (including proximity fitting)
Data organisation• Phased Partitioning
• Spatial Partitioning
Geometrical updating
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Geometrical updating
Condition at time i
Initial action
Primary data Observations
View Coordinates
l0 xi
1
0
ll
2
1
0
lll
nl
lll
2
1
0
xi+1
xi+2
xi+n
Copy
Adjustment
Adjustment
Adjustment
View 1
View 2
View n
1. Update
2. Update
n. Update
Time
Phased partitioning
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Geometrical updating
1. Update
2. Update
n. Update
Calculation areas are adjoint:
They may have shared elements.
Updating blocks Calculation areas
Updating blocks are disjoint:
They do not have shared elements.
Spatial partitioning
Important:Fixed borders!
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Geometrical updating
Updating block
EDBS-Object (Lower Saxony)
Simple example
Calculation areaidentical to
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Thank you for your attention.