Enable selection of range spacing or azimuth time interval in the STATIC runconfig

python/packages/nisar/workflows/static.py

@@ -110,20 +110,44 @@ def run_static_layers_workflow(config_file: os.PathLike | str) -> None:
     # parameters than the legacy `geo2rdr` routine that's used by most of the
     # workflow. Exposing both sets of parameters would introduce a lot of
     # additional bookkeeping for seemingly little benefit.
-    logger.info("Estimate maximum required radar grid spacing")
     radar_grid_params = processing_params["radar_grid"]
     look_side = radar_grid_params["look_side"]
     wavelength = radar_grid_params["wavelength"]
-    az_spacing, rg_spacing = \
-        isce3.geometry.infer_radar_grid_spacing_from_geo_grid(
-            geo_grid=geo_grid,
-            dem=dem_interp,
-            orbit=orbit,
-            doppler=img_grid_doppler,
-            look_side=look_side,
-            wavelength=wavelength,
-            **radar_grid_params["spacing"],
-        )
+
+    radar_grid_spacing_params = radar_grid_params["spacing"]
+    az_spacing = radar_grid_spacing_params["az_spacing"]
+    rg_spacing = radar_grid_spacing_params["rg_spacing"]
+    pts_per_side = radar_grid_spacing_params["pts_per_side"]
+
+    if az_spacing is not None and not (az_spacing > 0.0):
+        raise ValueError(f"Runconfig {az_spacing=}, must be > 0")
+
+    if rg_spacing is not None and not (rg_spacing > 0.0):
+        raise ValueError(f"Runconfig {rg_spacing=}, must be > 0")
+
+    logger.info("Estimate radar grid spacing")
+    if rg_spacing is not None:
+        logger.info(f'    range spacing: {rg_spacing}')
+    if az_spacing is not None:
+        logger.info(f'    azimuth time interval: {az_spacing}')
+
+    if rg_spacing is None or az_spacing is None:
+        az_spacing_inferred, rg_spacing_inferred = \
+            isce3.geometry.infer_radar_grid_spacing_from_geo_grid(
+                geo_grid=geo_grid,
+                dem=dem_interp,
+                orbit=orbit,
+                doppler=img_grid_doppler,
+                look_side=look_side,
+                wavelength=wavelength,
+                pts_per_side=pts_per_side
+            )
+        if rg_spacing is None:
+            logger.info(f'   inferred range spacing: {rg_spacing}')
+            rg_spacing = rg_spacing_inferred
+        if az_spacing is None:
+            logger.info(f'   inferred azimuth time interval: {az_spacing}')
+            az_spacing = az_spacing_inferred
 
     # Compute a radar grid whose footprint on the ground encloses the geocoded
     # grid on which each output layer is defined.

share/nisar/defaults/static.yaml

@@ -225,6 +225,16 @@ runconfig:
         # Defaults to 0.24.
         wavelength: 0.24
         spacing:
+          # [OPTIONAL] Azimuth time interval, in seconds. Equivalent to the Pulse
+          # Repetition Interval (PRI).
+          # If not provided, it will be inferred from the specified geographic
+          # grid. If provided, must be a positive value.
+          az_spacing:
+          # [OPTIONAL] Slant-range spacing, in meters, of the radar grid.
+          # Must be a positive value.
+          # If not provided, it will be inferred from the specified geographic
+          # grid. If provided, must be a positive value.
+          rg_spacing:
           # [OPTIONAL] Side length of the NxN grid of samples used to estimate the
           # required radar grid pixel spacing necessary to avoid undersampling the
           # output geocoded grid.

share/nisar/schemas/static.yaml

@@ -94,6 +94,8 @@ radar_grid_options:
   bounding_box: include('radar_grid_bounding_box_options', required=False)
 
 radar_grid_spacing_options:
+  az_spacing: num(min=0.0, required=False)
+  rg_spacing: num(min=0.0, required=False)
   pts_per_side: int(min=2, required=False)
 
 radar_grid_bounding_box_options: