The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B7. Beijing 2008
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It is important to note that the fringes are very clear in the
heavily vegetated area, and the phase can still be unwrapped
correctly. A maximum subsidence of approximately 40cm has
been measured at the Appin Mine site between the period 29
Jun 2007-14 Aug 2007. It is observed that the phase
discontinuities and decorrelation problems are much less in the
case of the ALOS PALSAR interferograms compared to the
ENVISAT ASAR interferograms, which is mainly due to the
fact that ALOS PALSAR images have finer spatial resolution
PALSAR has much higher successful rate for generating
displacement maps, especially for pairs with difference of only
1 repeat cycle. With this advantage, six successive subsidence
maps were able to be generated with eight ALOS PALSAR
images from both ascending and descending orbit acquisitions.
The 6 DInSAR results generated from interferograms 2-7
(Table 1) are post-processed and overlaid on the mine plan in
Figure 6. The location has been confirmed by comparison with
the actual mine schedule.
Interferogram
Pair 1
Pair 2
Oribit Heading
Period
(Days)
Perpendicular
Baseline (m)
Date
Mode
Date
Mode
1
27 Dec 2006
FBS
11 Feb 2007
FBS
Ascending
46
530
2
29 Jun 2007
FBD
14 Aug 2007
FBD
Ascending
46
45
3
14 Aug 2007
FBD
29 Sep 2007
FBD
Ascending
46
-501
4
29 Sep 2007
FBD
14 Nov 2007
FBS
Ascending
46
-110
5
14 Nov 2007
FBS
30 Dec 2007
FBS
Ascending
46
-735
6
30 Dec 2007
FBS
14 Feb 2008
FBS
Ascending
46
24
7
06 Feb 2008
FBS
23 Mar 2008
FBS
Descending
46
-127
Table 1. ALOS PALSAR interferogram data used for this study.
Figure 4. (Left) Mine plan overlaid with high resolution optical
image. (Right) ENVISAT ASAR differential interferogram
acquisition during 05 Jul 2007-09 Aug 2007 (35 days) with
Bperp (perpendicular baseline) = 89.94m, ascending pass, IS1
on (upper right) Westcliff Mine and (lower right) Appin Mine.
Figure 5. (Left) Mine plan overlaid with high resolution optical
image. (Right) ALOS PALSAR differential interferogram
acquisition during 29 Jun 2007-14 Aug 2007 (46 days) with
Bperp = 44.75m, ascending pass, on (upper right) Westcliff
Mine and (lower right) Appin Mine.
4.3 Validation
Subsidence (cm)
■i-M MM-»
Figure 6. Colour-coded DInSAR-derived subsidence maps from
ALOS PALSAR data pairs from (a) 29 Jun 2007-14 Aug 2007,
(b) 14 Aug 2007-29 Sep 2007, (c) 29 Sep 2007-14 Nov 2007,
(d) 14 Nov 2007-30 Dec 2007, (e) 30 Dec 2007-14 Feb 2008,
(f) 06 Feb 2008-23 Mar 2008. Positive displacement indicates
subsidence.