Dear all,
Digging into SNAP functionalities, I found an operator that retained my attention : S-1 Double Difference Interferogram with the description :
The operator computes the double difference interferogram for co-registered Sentinel-1 TOPS product for overlapped area between adjacent bursts.
To be sure : does-it mean that we substract from the interferogram built with burst i the interferogram with burst i+1?
(EDIT : I found my answer here : https://github.com/senbox-org/s1tbx/blob/master/s1tbx-op-sentinel1/src/main/java/org/esa/s1tbx/sentinel1/gpf/DoubleDifferenceInterferogramOp.java)
Related code
final double[][] mIBack = getSourceData(mstBandI, overlapInBurstTwoRectangle);
final double[][] mQBack = getSourceData(mstBandQ, overlapInBurstTwoRectangle);
final double[][] sIBack = getSourceData(slvBandI, overlapInBurstTwoRectangle);
final double[][] sQBack = getSourceData(slvBandQ, overlapInBurstTwoRectangle);
final double[][] mIFor = getSourceData(mstBandI, overlapInBurstOneRectangle);
final double[][] mQFor = getSourceData(mstBandQ, overlapInBurstOneRectangle);
final double[][] sIFor = getSourceData(slvBandI, overlapInBurstOneRectangle);
final double[][] sQFor = getSourceData(slvBandQ, overlapInBurstOneRectangle);
final double[][] backIntReal = new double[h][w];
final double[][] backIntImag = new double[h][w];
complexArrayMultiplication(mIBack, mQBack, sIBack, sQBack, backIntReal, backIntImag);
final double[][] forIntReal = new double[h][w];
final double[][] forIntImag = new double[h][w];
complexArrayMultiplication(mIFor, mQFor, sIFor, sQFor, forIntReal, forIntImag);
final double[][] diffIntReal = new double[h][w];
final double[][] diffIntImag = new double[h][w];
complexArrayMultiplication(forIntReal, forIntImag, backIntReal, backIntImag, diffIntReal, diffIntImag);
final double[][] ddiPhase = new double[h][w];
for (int i = 0; i < h; ++i) {
for (int j = 0; j < w; ++j) {
ddiPhase[i][j] = Math.atan2(diffIntImag[i][j], diffIntReal[i][j]);
}
}
return ddiPhase;[/details]
If yes, what is the point of doing this ? I was thinking about phase closure but it needs 3 interferograms.
Thanks in advance,
QG