> [!abstract] Summary > Practical notes on lighting with Arnold in Maya — covering light types, parameters, filters, light linking, and optimization tips for cleaner renders. > [!info] Related > Intro to render engines: [[../../../OUT OF PUBLISH/RENDERING/RENDERING basics Practice Alfh]] --- # Types of Lights | Light | Use case | | ---------------- | ---------------------------------------------------- | | **Area** | General lighting — several shapes available | | **Mesh Light** | Emissive geometry, useful for neon and practicals | | **Point** | Maya point light + Arnold exposure parameter | | **Skydome** | Environment / overcast lighting with an HDRI | | **Light Portal** | Reduces noise when lighting interiors with a Skydome | | **Photometric** | Real-world light profiles (IES files) | ## Skydome - Right-click **Color → File** to load an HDRI. - If the image is noisy, **increase the Skydome sample count**. > [!tip] Backplate setup (visible HDRI in the background without affecting lighting) > 1. Create > Polygon Primitives > Sphere > 2. Move and scale the sphere around the scene > 3. Mesh Display > Reverse (normals face inward) > 4. Apply an Arnold `aiStandardSurface` material > 5. Plug the HDRI texture into the Color slot > 6. Select the sphere → Attribute Editor → `pSphereShape` > 7. Arnold section → Visibility > 8. Uncheck everything **except Primary Visibility** — sphere shows in the background but does not affect lighting ## Light Portal Used alongside a Skydome to light an interior scene with less noise. | Portal Mode | Behaviour | | ------------------- | ------------------------------------------------------- | | `off` | Portals disabled | | `interior_only` | Blocks all light outside portals (pure interior scenes) | | `interior_exterior` | Lets light through outside portals (mixed scenes) | > [!tip] Blocking all lights except portals significantly reduces interior noise. --- # Light Parameters | Parameter | Effect | | --------------------------- | ---------------------------------------------------------------------------------------------------- | | **Normalize** | Adjust shadow softness by changing the light size (radius) without affecting overall light intensity | | **Cast Volumetric Shadows** | Enables shadows inside volumetric fog | | **Cone Angle** | Controls spot-light spread | | **Falloff** | Controls how light intensity decreases with distance | --- # Light Filters - **Barndoor** — Crops the light area on all axes *(spot light only)* - ![[download.jpg]] - **Gobo** — Projection filter, masks the light with a texture or shape *(spot light only)* - ![[ac-filter-gobo-gobo-blinds-A-without-slide-map-9.jpg|225]] - ![[ac-filter-gobo-gobo-blinds-B-with-slide-map-10 1.jpg|225]] - ![[ac-filter-gobo-gobo-blinds-C-slide-texture-11.jpg|225]] - **Light Blocker** — Blocks light in a specific region without adding geometry to the scene - **Light Decay** — Artistic falloff control, manual attenuation of the light - ![[ac-light-decay-image2019-12-16-13-39-26-1.png]] --- # Light Linking **Windows > Relationship Editor > Light Linking** — can be set per light (light-centric) or per object (object-centric). --- # Optimization > [!important] Shadow & specular noise > Increase **light sample count** when you see noise in shadows or direct specular. This is the sample that can be raised the highest. > **Watch out:** Camera AA multiplies this value — raise carefully. > [!tip] Size vs. noise trade-off > **The larger the light, the softer the shadow — but the more samples you will need to denoise those shadows.** > [!warning] Fireflies > A light too close to an object will create fireflies. Fix by moving the light further away, or use the **Near Distance Falloff** parameter. ---