ws 1 - workshop 1 quality management for geodata

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“

http://www.technet-gmbh.com/index.htm

www.technet-gmbh.com Geometrical Improvement of Geodata 2

• Short introduction to technet• Geometrical deficiencies • Geometrical updating

Topic Overview



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



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)



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)



Stressles coordinates Integrative analysis information

Geodetic measurements

Vectorized Cadastre maps

Cadastral field books

Utility geodata with constraints

Introduction

Geodata source examples

Adjustment delivers:

Orthophotos



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



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“



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:



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:



Geometrical deficiencies

Differences between cadastre map and orthophoto

Map and orthophoto do not fit together

Deficiency example 1:



Differences between point list and field book evidence

Field book numbers were (and are mostly still) not used consequently for coordinates calculation







Points have different input accuracies

Differences in the German ALK: point database and graphical database




First of all...

Topological disordance• Identical points between datasets - cannot be detected - are wrongly connected



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


The role of point topology




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




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



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




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



Intial situation Proximity fitting


Test example

Helmert transformationwithout constraintsProximity fitting with constraintsInitial situation

Comparison:



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





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




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!




Updating block

EDBS-Object (Lower Saxony)

Simple example

Calculation areaidentical to



Thank you for your attention.


ws 1 - workshop 1 quality management for geodata

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