Update README.md
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README.md
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@@ -80,9 +80,9 @@ The data preparation involves two major phases: GEE Acquisition and Local Post-P
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| **S1** | **Orbit Priority:** Prioritizes **DESCENDING** orbit images; falls back to **ASCENDING** if no valid DESCENDING image is found. | |
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| | **Data Filters:** $\text{instrumentMode} = \text{'IW'}$, $\text{resolution\_meters} = 10$, $\text{transmitterReceiverPolarisation} = \text{['VV', 'VH']}$. | |
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### 3.2. Local Post-Processing
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The
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1. **Reference Center Calculation:** The geographic coordinates ($\text{lon}$, $\text{lat}$) of the center pixel of the **first image** in the raw sequence are used as the consistent cropping reference point.
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2. **CRS and Transform Alignment:**
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### 4.2. Limitations and Caveats
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* **Temporal Gaps:** The data relies on a $\pm 30$ day window around seasonal peaks. The actual acquisition date can vary widely within this
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* **Resampling Method:** The use of Nearest Neighbor resampling for reprojection preserves original pixel values but may lead to minor geometric imperfections or stair-step effects on boundaries, especially if the raw image CRS significantly differed from the final majority CRS.
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* **Cloud Cover (S2):** Although filtered, the S2 data can still contain up to $20\%$ cloud cover or shadow pixels. Further masking or cloud removal may be necessary for some applications.
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* **S1 Orbit Mix:** While the S1 workflow prioritizes DESCENDING, some time steps may rely on ASCENDING images. Users should account for the potential change in look angle and its effect on SAR backscatter signatures.
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| **S1** | **Orbit Priority:** Prioritizes **DESCENDING** orbit images; falls back to **ASCENDING** if no valid DESCENDING image is found. | |
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| | **Data Filters:** $\text{instrumentMode} = \text{'IW'}$, $\text{resolution\_meters} = 10$, $\text{transmitterReceiverPolarisation} = \text{['VV', 'VH']}$. | |
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### 3.2. Local Post-Processing for Sentinel-1 GRD images
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The following steps were applied to the raw downloaded GeoTIFFs:
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1. **Reference Center Calculation:** The geographic coordinates ($\text{lon}$, $\text{lat}$) of the center pixel of the **first image** in the raw sequence are used as the consistent cropping reference point.
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2. **CRS and Transform Alignment:**
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### 4.2. Limitations and Caveats
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| 105 |
+
* **Temporal Gaps:** The data relies on a $\pm 30$ day window around seasonal peaks. The actual acquisition date can vary widely within this window, leading to some temporal jitter.
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| 106 |
* **Resampling Method:** The use of Nearest Neighbor resampling for reprojection preserves original pixel values but may lead to minor geometric imperfections or stair-step effects on boundaries, especially if the raw image CRS significantly differed from the final majority CRS.
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| 107 |
* **Cloud Cover (S2):** Although filtered, the S2 data can still contain up to $20\%$ cloud cover or shadow pixels. Further masking or cloud removal may be necessary for some applications.
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| 108 |
* **S1 Orbit Mix:** While the S1 workflow prioritizes DESCENDING, some time steps may rely on ASCENDING images. Users should account for the potential change in look angle and its effect on SAR backscatter signatures.
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