SALSIT (small area least-squares InSAR tool) is a set of scripts in the octave language, made for InSAR processing of satellite SAR data. The processing is based on the least-squares (LS) method, the ambiguities are estimated based on the similarity with close points. Coherence is not maximized here, but standard deviation of the residues is minimized. Therefore, the resulting coherence is lower than for softwares maximizing the coherence, estimated parameters are similar. Reliable results are achieved for datasets which are long enough. Implementation of standard FFT-based method is planned for the future.
The input of the software is the set of interferograms after the flat-Earth and topo phase subtraction, in the same format as required by the STAMPS software. Data in this format can be achieved by InSAR processing with the DORIS or SNAP software. In the case of Sentinel-1 data it is necessary to coregister the data with the very high accuracy in the azimuth direction (using the ESD method). In addition to the cite, some more easily createble files are needed. System can be used for PS processing of data from all SAR satellites.
Software does not estimate (and subtract) atmospheric delay. Therefore, it is useful for processing of a small area, or, it is possible to estimate and subtract the atmospheric delay from the input data before applying the software.
The output is the estimation of movement velocity, residual height (the DEM used for the topo phase subtraction, is also the part of the input data) and movement time series for the individual processed points. Also the standard deviation of all the parameters.
The software is designed for batch processing (non-interactive), it is easily adjustable and modular, many parameters can be directly changed.
Right now, SB processing (for landslide monitoring and monitoring of movements in vegetated areas) is not possible, but we plan this feature for the future.
Right now the software is not public, even for non-commercial applications. If you would like to help with testing or writing the documentation, cooperation is possible: please write an e-mail to hlavacova@insar.cz and the limited version can be released.
Limited version contains the basic estimation of velocity and heigh correction for points which are close to each other (the network of the points is done by triangulation). For configuration, it is necessary to directly edit the source code. In comparison to the full version, it does not contain automatic estimation of thresholds for filtering points or images, exclusion of problematic images, point densification, point position recalculation based on the adjusted height correction, Shenzen algorithm, and other features.
Changed 6. 02. 2021, hlavacova@insar.cz