An algorithm for upsampling spotlight SAR imagery: a Radarsat-2 SLC perspective
Bibliographic record
Abstract
This paper presents a novel algorithm for upsmapling level-1 processed (i.e., focused) Spotlight SAR imagery. A Spotlight Radarsat-2 single look complex (SLC) image for ground-truthed vehicle targets in Long-Harbour, Newfoundland (Canada) is used to demonstrate the applicability of our proposed algorithm. To achieve a finer resolution in the azimuth direction, the Spotlight imaging mode allows for a controllable steering of the radar antenna towards the same ground position. In effect, this creates a time-varying Doppler centroid system, wherein the Doppler centroid varies almost linearly with the platform velocity. Although the focused Spotlight Radarsat-2 SLC imagery is delivered referenced to zero-Doppler, linear variations in the Doppler frequency are preserved along the range direction around the zero-Doppler line. The impact of this effect on SAR image upsampling is pinpointed and accounted for in our proposed upsampling algorithm.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".