Hello STEP community,
I’m encountering a persistent error when trying to perform DEM-Assisted Coregistration
with Cross-Correlation on COSMO-SkyMed SLC Stripmap data using SNAP 13 (latest update).
ERROR MESSAGE:
Cannot invoke “org.esa.snap.core.datamodel.RasterDataNode.getSourceImage()” because
“rasterDataNode” is null
SNAP VERSION:
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SNAP 13.0.0 (fully updated via Help → Check for Updates)
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Operating System: Windows [specifica la tua versione]
DATA SPECIFICATIONS:
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Sensor: COSMO-SkyMed (CSK)
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Product Type: SCS_B (Stripmap HImage)
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Polarization: HH
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Processing Level: Level 1A (SLC)
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Master: 07-Sep-2018 (Orbit 60874, Track 99999)
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Slave: 23-Sep-2018 (Orbit 61111, Track 99999)
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Temporal Baseline: 16 days
PROCESSING WORKFLOW:
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Opened both products in SNAP via File → Open Product
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Launched: Radar → Coregistration → DEM-Assisted Coregistration with XCorr
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Added both products to ProductSet-Reader via drag-and-drop
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Configured parameters (see screenshots attached)
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Clicked “Run”
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Error appears immediately at the bottom of the dialog
PARAMETERS USED:
DEM-Assisted-Coregistration Tab:
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Digital Elevation Model: SRTM 3Sec (Auto Download)
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DEM Resampling Method: BILINEAR_INTERPOLATION
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Resampling Type: BILINEAR_INTERPOLATION
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Tile Extension: 100%
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✓ Mask out areas with no elevation
Cross-Correlation Tab:
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Number of GCPs: 20000
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✓ Apply Fine Registration for SLCs
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✓ Estimate Initial Coarse Offset
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Coarse Window Width/Height: 256
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Row/Column Interpolation Factor: 8
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Max Iterations: 5
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GCP Tolerance: 0.25
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Fine Window Width/Height: 64
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Coherence Threshold: 0.1
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Fine Accuracy in Azimuth/Range: 16
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Fine Window oversampling factor: 16
Warp Tab:
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RMS Threshold: 0.05
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Warp Polynomial Order: 1
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Interpolation Method: Bilinear interpolation
WHAT I’VE TRIED:
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Reduced the number of GCPs (from 20000 to 500) → same error
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Changed DEM from SRTM 3Sec to SRTM 1Sec → same error
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Simplified parameters (default values) → same error
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Used Graph Builder instead of GUI → same error with additional Graph XML error
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Restarted SNAP and reloaded products → same error
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Verified products load correctly in Product Explorer (both show bands and metadata)
QUESTIONS:
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Is this a known bug in SNAP 13 with COSMO-SkyMed SLC data?
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Could this be related to the BEAM-DIMAP format or product structure?
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Are there specific requirements for CSK product preprocessing before coregistration?
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Should I try an older SNAP version (e.g., SNAP 10)?
SCREENSHOTS:
[Attach the 4 screenshots showing: ProductSet-Reader, DEM tab, Cross-Correlation tab,
Warp tab - all displaying the error message]
Any help would be greatly appreciated! I need to process this data for InSAR analysis.
Thank you in advance,
