according to the mapping guidelines of the Korea National
Geographic Information Institute(NGII). Then we compare
plotted features of each image and reference data, analyze the
relation between the number of plotted features and image
quality. The result of experiments will be able to show critical
parameters of image quality on digital map generation.
2. DATASETS AND STUDY AREA
In this experiments, high resolution satellite images, QuickBird,
IKONOS and KOMPSAT-2, were used. The study area was
over Daejeon, Korea. The area included major layers of 1:5000
digital map feature catalogues such as railroad, river, road,
building, type of ground, facilities and topography. Figure 1, 2
and 3 shows QuickBird, IKONOS and KOMPSAT -2 stereo
pair over Daejeon, Korea, and Table 1 , 2 and 3 indicate their
properties.
Figure 1. QuickBird stereo pair over Daejeon, Korea
Table 1. The properties of the used QuickBird stereo pair.
Left ight
Sensor i ird
Date of isition 15 Jan 2005
GSD X(m 0.829
GSD Y(m 0.708
No.GCP 22
Figure 2. IKONOS stereo pair over Daejeon, Korea
Table 2. The properties of the used IKONOS stereo pair.
Left ight
Sensor IKONOS-2
Date of isition 7 Jul 2002
GSD X(m 0.900
GSD Y(m 0.960
No.GCP 10
Figure 3. KOMPSAT-2 stereo pair over Daejeon, Korea
Table 3. The properties of the used KOMPSAT-2 stereo pair.
Left ight
Sensor KOMPSAT-2
Date of isition 10 May 2007
GSD X(m 1.295 1.042
GSD Y(m 1.095 1.013
No.GCP 16 16
3. METHODOLOGY
Estimation of Image Quality
The image quality parameters such as RER(Relative Edge
Response), GSD, SNR, GRD and NIIRS are used widely. As
mentioned above, however, GSD does not reflected image
interpretability sufficiently. SNR, which tells the amount of
noise of images, is not appropriate to explain the overall quality
of image since it can only describe specific aspects of the image
quality. Thus it is issued to use RER, GRD and NIIRS that
indicate image interpretability. RER is estimated as the
difference of edge response at -0.5 pixel and +0.5pixel from the
center of edge. GRD and NIIRS are determined by equations
including image quality parameters that estimated by edge
analysis method. The artificial targets that is needed for edge
analysis have some problems such as high cost to set up. For
these reasons, our previous researches performed to estimate
GRD and NIIRS using natural targets and validated for
reliability of results(Kim et al., 2010; Kim and Kim, 2011).
In this experiment, we measured RER, SNR, GRD and NIIRS
using edge analysis method based on natural targets. NIIRS is
estimated by two versions with different coefficients.
Generation of 1:5000 Scale Digital Map
According to the guidelines of NGII, digital map scaled by
1:5000 is composed of 587 geographic feature layers and this
study area includes 95 layers of these layers. Also, layers
dependant to image acquisition time, required field survey,
reference data and additional editing were excluded because maps
were plotted using only digital photogrammetric workstation
here. After this process, 33 layers of 95 layers were possible to
plot. Figure 4 presents the result of digital map generation using
aerial photograph over study area. This map was used as the
122
es ^——
TM (fj — e 9 US (70 t9 n] (n8