The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part Bl. Beijing 2008
rectifided image with RPCs, DEM and GCPs. For ortho-
rectified image produce, the RPCs has to effect to change the
distance depending on height. (See Figure 6)
Figure 6. Height influence according to different height.
Figure 7. Generated ortho-rectified image using RPCs, GCP
and DEM
We also tested ortho-rectified image, the step of ortho-rectified
image is as following
Step 1: Open a FIR product using commercially available
softerware (PCI, ENVI)
I ENVI S/W was used
Step 2: Select RPC tool and read K.2 RPC file
! The RPC has different denominators with 3rd-order
polynomial from KOMPSAT-2
* Step 3: Refined RFM with GCPs ; choose different Z values
for each GCP: check if RMS is consistent with the true Z error.
Used GCPs number for refined KOMPSAT-2 is 8 points and
90m SRTM DEM was used to ortho-rectified image. The
generated product is Figure 5. To evaluate ortho-rectified image
by RPC, we compare the resulted direct sensor model with RPC
result.
In Figure 6 and Figure 7, it is possible to use KOMPSAT-2
RPC instead of KOMPSAT-2 DSM for 3D processes like ortho
rectification, stereo restitution or correlation.
4. CONCLUSION
The KOMPSAT-2 geometric accuracy verification was
successfully evaluated from 2007 through 2008. The 121 test
sites provided excellent condition for geometric verification due
to its flat terrain and a very good grid infrastructure.
This paper investigation is to check and verify the geometrical
performance when KOMPSAT-2 images data with precision
orbit data, precision attitude data are employed and briefly
introduce the direct sensor model and rational function model of
KOMPSAT-2. The ephemeris, attitude, time and image data
from KOMPSAT-2 acquired and direct sensor model or RFM
could be met 51.65m (CE90) geometric accuracy on the flat
ground. For the future research work, we should continue the
calibration and validation of KOMPSAT-2, after KOMPSAT-2
Cal/Val Phase II, more excellent and accurate results can be
come out.
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