Brighten default material previews and refresh documentation

docs/source/guides/preview_material.md

@@ -83,13 +83,32 @@ Each renderer must run in a separate process. `--gallery` requires Pillow and
 matplotlib; install those packages if they are absent. Gallery composition runs
 after native renderer cleanup and uses the saved captures.
 
+## Studio lighting
+
+The default `material-studio-v2` recipe uses the same lighting for every preset
+so material appearances can be compared:
+
+| Setting | Value |
+| --- | ---: |
+| Linear exposure multiplier | 1.6 |
+| Environment emission intensity | 48 |
+| Key rectangle light intensity | 150 |
+| Fill rectangle light intensity | 120 |
+
+Light colors, geometry and camera poses are fixed by the preview scene.
+These settings are recorded in `results.json` under `lighting`, alongside the
+`scene` recipe identifier. The catalog images use this recipe at 640×640,
+six accumulation frames and 12 render iterations per frame. Material parameters
+remain the authored preset values.
+
 ## Outputs and direct-native verification
 
 Every render writes `<PresetName>_preset.png` and `results.json` under
 `--output` (default `outputs/default-materials`). Use a separate directory per
 variant or renderer to retain previous results. The report records the scene
-recipe, renderer and DexSim version, capture settings, material source/revision,
-serialized configuration, geometry choice, parameter readback and exclusions.
+recipe and lighting, renderer and DexSim version, capture settings, material
+source/revision, serialized configuration, geometry choice, parameter readback
+and exclusions.
 Unspecified configuration fields stay `null`; authored resource defaults are
 not expanded into explicit overrides.
 

docs/source/overview/sim/sim_manager/rendering/materials.md

@@ -6,9 +6,11 @@ EmbodiChain provides **24 public material presets** through one
 material supplies the inward-facing interface for the bubble preview.
 
 The images below are actual DexSim **0.5.1rc1 OfflineRT** renders. All presets
-use the same studio lighting and exposure; a checkerboard and colored cards
-make reflection, transmission and roughness visible. Click a material name in
-a table to open its individual image.
+use the same `material-studio-v2` lighting recipe: linear exposure 1.6,
+environment intensity 48, key light intensity 150 and fill light intensity 120.
+A checkerboard and colored cards make reflection, transmission and roughness
+visible. Click a material name in a table to open its individual image. See the
+{doc}`preview guide </guides/preview_material>` for reproduction settings.
 
 ## Create and override a material
 

embodichain/lab/scripts/preview_material.py

@@ -38,6 +38,13 @@
 
 __all__ = ["main", "cli"]
 
+_STUDIO_LIGHTING = {
+    "exposure": 1.6,
+    "environment_intensity": 48.0,
+    "key_intensity": 150.0,
+    "fill_intensity": 120.0,
+}
+
 
 def _positive_integer(value: str) -> int:
     number = int(value)
@@ -344,7 +351,7 @@ def _render_materials(
                 min_bounces=3,
                 max_bounces=14,
                 tone_mapping_enabled=True,
-                tone_mapping_exposure=0.9,
+                tone_mapping_exposure=_STUDIO_LIGHTING["exposure"],
                 denoising=DenoisingCfg(window="optix", offscreen="optix"),
             ),
         )
@@ -355,7 +362,9 @@ def _render_materials(
     rows: list[dict[str, Any]] = []
     try:
         sim.enable_physics(False)
-        sim.set_emission_light([0.85, 0.9, 1.0], 24.0)
+        sim.set_emission_light(
+            [0.85, 0.9, 1.0], _STUDIO_LIGHTING["environment_intensity"]
+        )
         # Independent, fixed scene: colored cards reveal transmission, broad
         # rectangular lights reveal roughness and normal-map direction.
         for index, (x, color) in enumerate(
@@ -381,8 +390,20 @@ def _render_materials(
                 texture = env.create_color_texture(pixels, has_alpha=False)
                 card_material.inst.set_base_color_texture(texture_obj=texture)
         for name, location, direction, color, power in (
-            ("key", (-2, -2, 3), (2, 2, -2), (1, 0.85, 0.7), 90),
-            ("fill", (2, 0, 3), (-2, 0, -2), (0.6, 0.8, 1), 60),
+            (
+                "key",
+                (-2, -2, 3),
+                (2, 2, -2),
+                (1, 0.85, 0.7),
+                _STUDIO_LIGHTING["key_intensity"],
+            ),
+            (
+                "fill",
+                (2, 0, 3),
+                (-2, 0, -2),
+                (0.6, 0.8, 1),
+                _STUDIO_LIGHTING["fill_intensity"],
+            ),
         ):
             light = env.create_light(name, render.LightType.RECT)
             light.set_location(*location)
@@ -612,7 +633,8 @@ def capture(label: str) -> Any:
             print(json.dumps(row), flush=True)
         report = {
             "schema_version": 1,
-            "scene": "material-studio-v1",
+            "scene": "material-studio-v2",
+            "lighting": dict(_STUDIO_LIGHTING),
             "renderer": args.renderer,
             "dexsim": version("dexsim-engine"),
             "size": args.size,