Download - Fitting, portayal and mapping
Artemis Valanis
School of Rural and Surveying Engineering
Laboratory of Photogrammetry
National Technical University of Athens, Greece
FITTING, PORTRAYAL AND MAPPING FOR THE PRODUCTION OF 2nd ORDER SURFACES PHOTOMOSAICS
GENERAL INFORMATION AND OBJECTIVESThis presentation refers to an extensive study that has
been carried out within the framework of a much greater project. The project was assigned to the Laboratory of Photogrammetry and involved the thorough survey and recording of the world famous Byzantine Daphni Monastery of Athens (11th century).
The main objective of this study was the creation of large-scale (1:5) developments of 2nd-order surfaces.
COURSE OF STUDY
Data collectionSurface fittingReference system definitionCreation of the “Intermediary Model”Choice of the most suitable projection Production of the developed images Creation of the photomosaics
PROBLEMS ENCOUNTERED
- The choice of the most suitable model
- The calculation of the approximate values of the unknowns
- The definition of a new reference system
- The fact that the mathematically defined surface generally differs from the real object surface
DATA USED
Photographs of scale: k= 1:25
Scanning resolution: 600 dpi
Geodetically collected point coordinates
Photo orientations
DEMs
SURFACE FITTING
- Choice of a model
- Calculation of the approximate values of the unknowns
- Creation of the least-squares adjustment programs with computational optimization
- Testing of the programs with simulation data
- Implementation with actual data
REFERENCE SYSTEM DEFINITION
MODEL OR REAL OBJECT SURFACE ?
However, the most important problem encountered was the fact that the mathematically defined surface generally differs from the real object surface.
Thus, in order for the photomosaicking to be possible, the one-to-one correspondence between the points of the real and the model surface had to be ensured. This was achieved with the creation of the “Intermediary Model”, which is based on the DEM of the real surface.
THE PROBLEM CAUSED DUE TO THE DIFFERENCE BETWEEN THE MODEL AND THE REAL SURFACE
(PP)
(Xc,Yc,Zc)
ModelReal Surface
(Ph1)
(Ph2)
ERROR PROPAGATION
Least-squares adjustment
σο dR = 3cm
|dR| 3cm (68%)
|dR| 6cm (95%)
|dR| 9cm (99%)
ERROR PROPAGATION
-15-10
-505
1015
-90 -60 -30 0 30 60 90
Longitude (degrees)
Err
or in
the
x po
sitio
n (c
m)
dR = 3cm dR=6cm dR=9cm
ERROR PROPAGATION
-30
-20
-10
0
10
20
30
-90 -60 -30 0 30 60 90
Latitude (degrees)
Err
or
in the
y p
osi
tion
(cm
)
dR = 3cm dR = 6 cm dR = 9cm
PROJECTION Choice of the most proper projection
Criteria:Suitability for the application
Minimization of the distortions Implementation:
Projection-plane (xp, yp) Sphere “Intermediary Model”
Actual object-surface
Geodetical coordinates
Coordinates on the photographic plane
Acquisition of the colour for the corresponding position (xp, yp) on the projection plane
Developed Image creation
RESULTS- Mollweide Conformal Projection -
RESULTS- Oblique Mercator Projection -
CHARACTERISTICS OF THE METHOD DEVELOPED
Accuracy and reliabilityHigh qualityAbility to work with RGB imagesCapability to incorporate numerous images for a
single objectSuccessful mosaickingProgram performance highly dependent on the
platform and the resources of the system used