ready for review

Author: konstntokas

CHANGES.md

@@ -1,6 +1,7 @@
 ## Changes in 0.2.5 (under development)
 
-* Added subsetting in analysis mode via parameter `bbox`.
+* Added subsetting and reprojection in analysis mode via parameters `crs`
+  `resolution` and `bbox`.
 
 ## Changes in 0.2.4 (from 2025-11-17)
 

docs/guide.md

@@ -36,25 +36,30 @@ form. All bands and quality flags are resampled to a unified, user-provided reso
 Parameters `**kwargs`:
 
 - `resolution`: Target resolution for all spatial data variables / bands.
+- `crs`: Coordinate reference system of the output dataset. If not provided, a
+  mission-specific default CRS is used (see the respective mission sections below).
+- `bbox`: Bounding box `[west, south, east, north]` used for spatial subsetting;
+  coordinates must be in the same CRS as `crs`.
 - `interp_methods`: for upsampling / interpolating
-    spatial data variables. Can be a single interpolation method for all
-    variables or a dictionary mapping variable names or dtypes to
-    interpolation method. Supported methods include:
+  spatial data variables. Can be a single interpolation method for all
+  variables or a dictionary mapping variable names or dtypes to
+  interpolation method. Supported methods include:
 
     - `0` (nearest neighbor)
     - `1` (linear / bilinear)
     - `"nearest"`
     - `"triangular"`
     - `"bilinear"`
 
-    The default is `0` for integer arrays (e.g. Sentinel-2 L2A SCL),
-    else `1`.
+  The default is `0` for integer arrays (e.g. Sentinel-2 L2A SCL),
+  else `1`. For more information view [xcube-resampling Documentation](https://xcube-dev.github.io/xcube-resampling/guide/#spatial-resampling-algorithms).
 - `agg_methods`: Optional aggregation methods to be used for downsampling
   spatial data variables / bands. Can be a single method for all variables or 
   a dictionary mapping variable names or dtypes to methods. Supported methods include:
     `"center"`, `"count"`, `"first"`, `"last"`, `"max"`, `"mean"`, `"median"`, 
     `"mode"`, `"min"`, `"prod"`, `"std"`, `"sum"`, and `"var"`.
   Defaults to `"center"` for integer arrays (e.g. Sentinel-2 L2A SCL), else `"mean"`.
+  For more information view [xcube-resampling Documentation](https://xcube-dev.github.io/xcube-resampling/guide/#spatial-resampling-algorithms).
 - `variables`: Variables to include in the dataset. Can be a name or regex pattern 
   or iterable of the latter.
 - `product_type`: Product type name, such as `"MSIL1C"`. 
@@ -90,10 +95,13 @@ bands from multiple resolutions onto the same grid using [affine transformation
 
 **Specific Sentinel-2 parameters `**kwargs`:**
 
-- `variables`: The common spectral band names specified in the [STAC EO extension](https://github.com/stac-extensions/eo?tab=readme-ov-file#common-band-names)
-  are supported for the Sentinel-2 analysis mode.
-- `resolution`: Target resolution for all spatial data variables / bands.
-  Must be one of `10`, `20`, or `60`.  
+- `variables`: Select specific spectral bands using the names listed above.
+  Common spectral band names from the [STAC EO extension](https://github.com/stac-extensions/eo?tab=readme-ov-file#common-band-names) are also supported for Sentinel-2 analysis mode.
+- `crs`: Coordinate reference system of the output dataset.
+  If not specified, the UTM grid of the native data is used.
+- `resolution`: Target resolution for all spatial variables/bands.
+  Choose 10, 20, or 60 meters to minimize resampling and retain some of the native
+  data resolution.
 
 Examples:  
 - [Example notebook - open-sen2.ipynb](https://github.com/EOPF-Sample-Service/xarray-eopf/blob/main/examples/open-sen2.ipynb)  
@@ -128,6 +136,19 @@ for details.
 - [Sentinel-3 SLSTR Level-1 RBT](https://stac.browser.user.eopf.eodc.eu/collections/sentinel-3-slstr-l1-rbt)
 - [Sentinel-3 SLSTR Level-2 LST](https://stac.browser.user.eopf.eodc.eu/collections/sentinel-3-slstr-l2-lst)
 
+**Specific Sentinel-2 parameters `**kwargs`:**
+
+- `crs`: Coordinate reference system of the output dataset.
+  If not specified, [EPSG:4326](https://epsg.io/4326) is used.
+- `resolution`: Target resolution for all spatial variables/bands.
+  If not specified, the default is set per product:
+
+    - Sentinel-3 OLCI Level-1 EFR: 300 meter
+    - Sentinel-3 OLCI Level-1 ERR: 1200 meter
+    - Sentinel-3 OLCI Level-2 LFR: 300 meter
+    - Sentinel-3 SLSTR Level-1 RBT: 500 meter (1000 meter if selected variables come from F- or I-stripe)
+    - Sentinel-3 SLSTR Level-2 LST: 1000 meter
+
 Example:  
 - [Example notebook (open-sen3.ipynb)](https://github.com/EOPF-Sample-Service/xarray-eopf/blob/main/examples/open-sen3.ipynb)