Fixed 2d projection monitor intersection error

CHANGELOG.md

@@ -59,6 +59,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Gradient inaccuracies in `PolySlab.vertices`, `Medium.conductivity`, and `DiffractionData` s-polarization.
 - Adjoint field monitors no longer store H fields, which aren't needed for gradient calculation.
 - `MeshOverrideStructures` in a `Simulation.GridSpec` are properly handled to remove any derivative tracers.
+- Error when field projection monitor intersecting structures outside of the simulation domain in 2D simulations.
 
 ## [2.7.1] - 2024-07-10
 

tests/test_components/test_simulation.py

@@ -2977,3 +2977,35 @@ def test_validate_sources_monitors_in_bounds():
             grid_spec=td.GridSpec(wavelength=1.0),
             monitors=[mode_monitor],
         )
+
+
+def test_2d_projection_monitor_out_sim_domain():
+    # set up a structure interset with far field monitor outside the computational domain
+    cylinder = td.Structure(
+        geometry=td.Cylinder(axis=2, radius=0.5, length=2), medium=td.PECMedium()
+    )
+
+    num_phi = 100
+    theta = np.pi / 2
+    phis = np.linspace(0, np.pi, num_phi)
+    monitor_far = td.FieldProjectionAngleMonitor(
+        size=[2, 2, 0.5],
+        freqs=[1e12],
+        name="far_field",
+        theta=theta,
+        phi=phis,
+    )
+
+    sim2d = td.Simulation(
+        size=(4, 4, 0),
+        run_time=1e-12,
+        grid_spec=td.GridSpec.uniform(dl=0.025),
+        sources=[],
+        structures=[cylinder],
+        monitors=[monitor_far],
+        boundary_spec=td.BoundarySpec(
+            x=td.Boundary.pml(),
+            y=td.Boundary.pml(),
+            z=td.Boundary.periodic(),
+        ),
+    )

tidy3d/components/simulation.py

@@ -136,6 +136,9 @@
 # height of the PML plotting boxes along any dimensions where sim.size[dim] == 0
 PML_HEIGHT_FOR_0_DIMS = inf
 
+# fraction of structure size to monitor along 0 dim in 2D simulations
+FRACTION = 0.9
+
 
 class AbstractYeeGridSimulation(AbstractSimulation, ABC):
     """
@@ -2741,6 +2744,15 @@ def _projection_monitors_homogeneous(cls, val, values):
         if val is None:
             return val
 
+        sim_size = values.get("size")
+
+        # Validation and return zero-dim index of 2D simulations
+        zero_dim_ind = None
+        is_2d_simulation = False
+        if sim_size.count(0.0) == 1:
+            zero_dim_ind = sim_size.index(0.0)
+            is_2d_simulation = True
+
         # list of structures including background as a Box()
         structure_bg = Structure(
             geometry=Box(
@@ -2756,7 +2768,26 @@ def _projection_monitors_homogeneous(cls, val, values):
         with log as consolidated_logger:
             for monitor_ind, monitor in enumerate(val):
                 if isinstance(monitor, (AbstractFieldProjectionMonitor, DiffractionMonitor)):
-                    mediums = Scene.intersecting_media(monitor, total_structures)
+                    if is_2d_simulation:
+                        exclude_surfaces_2d = {
+                            0: ["x-", "x+"],
+                            1: ["y-", "y+"],
+                            2: ["z-", "z+"],
+                        }.get(zero_dim_ind)
+                        monitor_dict = monitor.dict()
+                        # Append exclude surfaces for 2D simulation to existing ones
+                        existing_exclude_surfaces = monitor_dict.get("exclude_surfaces") or []
+                        updated_exclude_surfaces = list(
+                            set(existing_exclude_surfaces + exclude_surfaces_2d)
+                        )
+                        monitor_dict["exclude_surfaces"] = updated_exclude_surfaces
+                        surfaces = monitor.surfaces_with_exclusion(**monitor_dict)
+                        mediums = set()
+                        for surface in surfaces:
+                            _mediums = Scene.intersecting_media(surface, total_structures)
+                            mediums.update(_mediums)
+                    else:
+                        mediums = Scene.intersecting_media(monitor, total_structures)
                     # make sure there is no more than one medium in the returned list
                     if len(mediums) > 1:
                         raise SetupError(