Optical physics in voxelized volumes

opengate/engines.py

@@ -415,6 +415,30 @@ def initialize_optical_material_properties(self):
             for (
                 vol
             ) in self.simulation_engine.simulation.volume_manager.volumes.values():
+                if hasattr(vol, "voxel_materials"):
+                    materials = [m[2] for m in vol.voxel_materials]
+                    materials.append(vol.material)
+                    for i in materials:
+                        for mat in g4.G4Material.GetMaterialTable:
+                            if str(mat.GetName()) == i:
+                                mat_prop = load_optical_properties_from_xml(
+                                    self.physics_manager.optical_properties_file,
+                                    mat.GetName(),
+                                )
+                                if mat_prop is not None:
+                                    self.g4_optical_material_tables[
+                                        str(mat.GetName())
+                                    ] = create_g4_optical_properties_table(mat_prop)
+                                    mat.SetMaterialPropertiesTable(
+                                        self.g4_optical_material_tables[
+                                            str(mat.GetName())
+                                        ]
+                                    )
+                                else:
+                                    self.simulation_engine.warn_user(
+                                        f"Could not load the optical material properties for material {mat.GetName()} "
+                                        f"found in volume {vol.name} from file {self.physics_manager.optical_properties_file}"
+                                    )
                 material_name = vol.g4_material.GetName()
                 material_properties = load_optical_properties_from_xml(
                     self.physics_manager.optical_properties_file, material_name

opengate/tests/src/physics/test098_optical_physics_voxelized_vol.py

@@ -0,0 +1,114 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+"""
+Created on Fri Oct  3 15:07:07 2025
+
+@author: mabbas
+"""
+
+import opengate as gate
+from opengate.tests import utility
+from opengate.utility import g4_units
+import SimpleITK as sitk
+import numpy as np
+
+if __name__ == "__main__":
+
+    paths = utility.get_default_test_paths(
+        __file__, "gate_test098", output_folder="gate_test098"
+    )
+
+    cm = g4_units.cm
+    mm = g4_units.mm
+    eV = g4_units.eV
+    nm = g4_units.nm
+
+    sim = gate.Simulation()
+    sim.output_dir = paths.output
+    sim.g4_verbose = False
+    sim.visu = False
+    sim.visu_type = "vrml"
+    sim.check_volumes_overlap = False
+    sim.number_of_threads = 2
+    sim.random_seed = "auto"
+
+    sim.volume_manager.add_material_database(paths.gate_data / "GateMaterials.db")
+
+    sim.physics_manager.special_physics_constructors.G4OpticalPhysics = True
+
+    sim.physics_manager.optical_properties_file = paths.gate_data / "Materials.xml"
+
+    sim.world.size = [6 * cm, 6 * cm, 2 * cm]
+    sim.world.material = "Air"
+
+    img_path = paths.data / "vox_volume.mhd"
+
+    img = sitk.ReadImage(img_path)
+    Spacing = img.GetSpacing()
+    Size = np.array(img.GetSize())  # Image size in number of voxels
+    Size2 = np.array(
+        [Size[i] * Spacing[i] for i in range(len(Size))]
+    )  # Image size in mm
+
+    vox = sim.add_volume("ImageVolume", "image")
+    vox.image = img_path
+    vox.material = "Air"
+    vox.voxel_materials = [
+        [
+            -0.5,
+            0.5,
+            "Fat",
+        ],
+        [0.5, 1.5, "Muscle"],
+    ]
+    vox.translation = [0, 0, 0]
+
+    phsp_plane = sim.add_volume("BoxVolume", "phsp_plane")
+    phsp_plane.material = "Air"
+    phsp_plane.size = [5 * cm, 5 * cm, 1 * nm]
+    phsp_plane.translation = [0, 0, (Size2[2] / 2) * mm + phsp_plane.size[2] / 2]
+
+    phsp = sim.add_actor("PhaseSpaceActor", "phsp")
+    phsp.attached_to = phsp_plane.name
+    phsp.attributes = ["PostPosition"]
+    phsp.steps_to_store = "exiting"
+    phsp.output_filename = "test098_vox_volume.root"
+
+    source = sim.add_source("GenericSource", "source")
+    source.particle = "opticalphoton"
+    source.energy.type = "mono"
+    source.energy.mono = 1.913 * eV
+    source.position.type = "disc"
+    source.position.radius = 1.25 * cm
+    source.direction.type = "momentum"
+    source.direction.momentum = [0, 0, 1]
+    source.position.translation = [0, 0, -(Size2[2] / 2) * mm]
+    source.n = 1e6 / sim.number_of_threads
+
+    sim.run()
+
+    compare = utility.compare_root3
+
+    root_ref_path = paths.data / "test098_box_volume.root"
+    root_output_path = sim.output_dir / phsp.output_filename
+
+    branch = "phsp;1"
+    keys = ["PostPosition_X", "PostPosition_Y", "PostPosition_Z"]
+    tols = [0.3, 0.3, 1e-4]
+    scalings = [1, 1, 1]
+    img = paths.output / "figure.png"
+
+    is_ok = compare(
+        root_ref_path,
+        root_output_path,
+        branch,
+        branch,
+        keys,
+        keys,
+        tols,
+        scalings,
+        scalings,
+        img,
+    )
+
+    utility.test_ok(is_ok)