FILE INCONSISTENCY error during a coregistration step in SARscape

Sometimes when performing coregistration or any type of interferogram generation (which includes a coregistration) in SARscape, one will receive an error message that says something like:

     SARscape error message

     FILE INCONSISTENCY [EC : 40001]

This can happen for a variety of reasons. Some datasets are just not coherent enough for SARscape to find enough points for a reasonable coregistration. For example, if everything in the scene has changed between datasets, coregistration can fail. This can happen if the area is heavily vegetated (because vegetation changes and moves a lot, and so can look very different from image to image at a particular location). We have also heard of coregistration failing for datasets from before and after a tornado that destroyed and changed everything in the scene. There really is not a solution for that problem. Sometimes if the problem is vegetation, and you are not mostly interested in the vegetated areas, then you can specify a relatively non-vegetated area to analyze. You would do this using the Sample Selections tools under SARscape > General Tools.

Some other problems that can occur:

For some datasets, the orbital data may not be precise enough for an accurate coregistration. SARscape may be able to update the orbital information, with precise orbit files that you get from the data provider. ERS and Radarsat-2 datasets are in this category. Once you have the precise orbit files, you can find the tools to apply them to the datasets under SARscape > General Tools > Orbital Correction > Update to Precise Orbits.

If the datasets have a lot of topography, it can be tricky to find good tie points between the datasets. In this case, you will want to be sure to specify a DEM during the coregistration. It will be necessary in this case to get good results. If you do not have a DEM, you can generate one that matches your master dataset in SARscape, using the tool under SARscape > General Tools > Digital Elevation Model Extraction > SRTM-3 Version 4 (you can extract a DEM for your area from any of the global DEM datasets listed under digital Elevation Model Extraction, but we recommend using an SRTM DEM).

Below are some parameters you might try changing, if you can't get coregistration after updating the orbital information or adding a DEM:

1. In the dialog where you set up the processing parameters, under the Parameters tab, choose Coregistration from the drop down menu near the top. Then try tripling the Range Window Number and Azimuth Window Number parameter values.

2. If that doesn't work, then leave those values at their new larger values and additionally try doubling the Range Window Size and the Azimuth Window Size.

 

Review by MMin, 2015-02-12