base for detailed point processing. The result is a line 3D model of the fortification.
The final point accuracy when using 53 photographs varies from several centimeters’ to 0.5 m depending on point position. Lower accuracy occurs on interior points
and on points with a mall beam intersection angle.
3.3.3.5 Vector Plan Creation
The survey of the entire Citadel interior by classical geodetic measurements is
hardly achievable. Part of it had been surveyed from building roofs; other parts
were processed from satellite images. No convenient images for vector plan
creation were acquired from the army helicopter flight due to its high speed (combat
type helicopter) and low flight height. Even if the flight height had been sufficient
many details were distorted or hidden. Due to this fact, an archived QuickBird
image with four multispectral channels (R, G, B, NIR) and one panchromatic
channel had been used. The resolution was 2.4 m in multispectral and 0.65 m in
panchromatic channel and the image was acquired on 2005-08-23. Pan sharpening
together with filtration methods and resampling to 25 cm pixel size had been
performed. The scene quality was excellent and together with geodetic survey
and PhotoModeller results these data were used for basic plan of the Citadel (see
Fig. 3.10).
The next necessary step was to transform the satellite data to geodetic coordinates using ground control points measured by geodetical survey. Polynomial highlevel transformation based on number of ground control points was performed. Due
to problems with PhotoModeler data transformation, affine transformation had been
used for different type data merging. The deviations vary between 10 and 30 cm,
which are sufficient when the resolution of satellite image is taken into account.
Fig. 3.10 (a) Scheme of control points and measured data: black (Photomodeler), green (total
station), red (control and geodetic points), black lines (vectorisation of satellite image, 8/2007),
red lines (electric line); (b) vector processing of the Al Qala Citadel
54
K. Pavelka and E. Matous ˇkova ´
The final point accuracy when using 53 photographs varies from several centimeters’ to 0.5 m depending on point position. Lower accuracy occurs on interior points
and on points with a mall beam intersection angle.
3.3.3.5 Vector Plan Creation
The survey of the entire Citadel interior by classical geodetic measurements is
hardly achievable. Part of it had been surveyed from building roofs; other parts
were processed from satellite images. No convenient images for vector plan
creation were acquired from the army helicopter flight due to its high speed (combat
type helicopter) and low flight height. Even if the flight height had been sufficient
many details were distorted or hidden. Due to this fact, an archived QuickBird
image with four multispectral channels (R, G, B, NIR) and one panchromatic
channel had been used. The resolution was 2.4 m in multispectral and 0.65 m in
panchromatic channel and the image was acquired on 2005-08-23. Pan sharpening
together with filtration methods and resampling to 25 cm pixel size had been
performed. The scene quality was excellent and together with geodetic survey
and PhotoModeller results these data were used for basic plan of the Citadel (see
Fig. 3.10).
The next necessary step was to transform the satellite data to geodetic coordinates using ground control points measured by geodetical survey. Polynomial highlevel transformation based on number of ground control points was performed. Due
to problems with PhotoModeler data transformation, affine transformation had been
used for different type data merging. The deviations vary between 10 and 30 cm,
which are sufficient when the resolution of satellite image is taken into account.
Fig. 3.10 (a) Scheme of control points and measured data: black (Photomodeler), green (total
station), red (control and geodetic points), black lines (vectorisation of satellite image, 8/2007),
red lines (electric line); (b) vector processing of the Al Qala Citadel
54
K. Pavelka and E. Matous ˇkova ´