International Archives of the Photogrammetry, Remote Sensing and Spatial [Information Sciences, Vol XXXV, Part B2. Istanbul 2004
Photo control processes, possible improvements:
- . Concerning: Automated control of photo-center
accuracy and overlap between neighboring photos.
Suggestion: lt is evident that GPS has already
minimized the number of photo-center errors. Use of
INS/IMU could improve positioning even more and
allow less attention to the photo-center control
- . Concerning: Visual control of the appearance of
photographic end-products. The production line from
2004 will no longer include photographic end-products.
But the in-house control procedures still demand contact
copies, to compensate for loss in detail in the scanned
images of 21 micron.
Suggestion: Need for contact copies disappear with a
better scan solution or by usages of digital cameras
- . Concerning: Manual random check of scanned images.
Suggestion: Automatic control of all images should be
implemented. Future use of digital cameras might make
control of scanned images unnecessary
Object control processes, possible improvements:
- . Concerning: Control of object geometry is currently in
2D, by polynomial rectified photos
Suggestion: Controlling all objects in all three
dimensions is essential, and can be solved by:
- Use of photogrammetric transformation of vector
data (X, Y, Z) into raw image
- Use of orthophotos
- Concerning: Control of object data according to
specifications, is currently by “hard-coded” routines.
Suggestion: Specification rules should be archived and
accessed in a database. This would also make it possible
to control object data according to their setup
specification
- . Concerning: Current control of data completeness is
performed visually by polynomial rectified images.
Suggestion: Automatic change detection or identical
accuracy and better correlation all around the image,
between image-objects and vector-objects is essential -
and can be solved by:
- Use of photogrammetric transformation of vector
data (X, Y, Z) into raw image
- Use of orthophotos.
- . Automatic detection and classification of objects /
changes in a image (Olsen, 2004)
2.4.2 Optimizing, control processes. It was recognized from
this evaluation process (2003), that object-geometry control
did have highest priority for development. A tool for
photogrammetric transformation of vector data to raw image
was therefore decided, as a new control procedure.
3. CONTROL OF 3D-DATA IN 2D-ENVIRONMENT
To illustrate the continuous development of the control
procedure used for TOPIODK, the chronicle steps of
optimizing object-geometry control are listed:
- In the database setup phase: random checks in 3D
- J Overall 2D-control by polynomial rectified images
- In the database update phase: overall 3D control, by
photogrammetric transformation of objects (X, Y, Z)
into the raw image
754
3.1 Photogrammetric transformation of vector data
The developed method for photogrammetric transformation
of vector data is called the “Vector Transformation" module
(VT module). It is implemented by approved photogram-
metric methodologies but is for practical and economical
reasons designed to work on PCs without stereoscopic view.
The VT module projects the vector data photogrammetrically
on top of the raw image, accounting for camera properties
and map-object coordinates (X, Y, Z).
The goal of the method is to develop a tool for the control of
geometric accuracy of individual map-objects in 3D so that:
- . Map-objects that are registered correctly in X, Y and Z —
will be displayed (draped) exactly on top of their
appearances in the raw image (as good as the
photogrammetric parameters allows).
- . The accuracy of the draping will be the same in the
whole image, meaning no need of shifting vector data in
the image periphery to match their appearances (as is
needed for polynomial rectified images — fig.4).
- When single map-objects are displaced from their
position in the image, something is wrong in that
specific object.
- . When all map-objects are displaced from their position
in the image, some fundamental error has occurred.
Error can be from the VT-parameter-calculation or from
the model orientation used by contractors for the object
extraction. Both can and must be checked.
Integrating the technique into production in KMS was done
with guidance from a research-project of the methodology
done by Jon C. Olsen (KMS). Functions were integrated in
the production and control software Mapcheck, and
facilitated with automation features.
3.2 Vector Transformation methodology
The Vector Transformation module is built on the
fundamental equations of photogrammetry. Parameters for
the transformation are calculated through the knowledge of
inner orientation (IO) and rotation (D) of the image. Stating
that coherence between vector map-objects in geographical
coordinates and their coordinates in image pixels, are
calculated for each image, by information about:
- Camera calibration
- Fiducial coordinates
- A number of well distributed ground control points.
The inner orientation is found through an affin transformation
of the six variables, for the coherence between fiducials
measured in image and data from the camera calibration,
solved with a least square calculation.
The rotation matrix (D) is evaluated by :
DX’= M (X-Xo)
D Y! « M(Y-Yy)
D -c = M (Z-Zy)
c
Where: M.
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