Memory housekeeping in Daz3D

Iray is a VRAM hog, but you can drastically cut down memory usage without sacrificing the visual quality of your final print or artwork. Here is a step-by-step optimization workflow to keep your renders firmly planted on your GPU.

Step 1: Global Settings & Diagnostics

Before changing the scene, change how DAZ handles textures globally and look under the hood.

• Turn on the Log File: Go to Help > Troubleshooting > View Log File. Keep this open or check it right after a render starts. Search for CUDA or VRAM. It will tell you exactly how much memory your scene is taking and if it failed to fit on the card.

• Instancing Optimization: Go to Edit > Preferences > CMS. Ensure your Cluster and Content Management Services are running smoothly, as DAZ relies heavily on instancing to save memory.

Step 2: The Biggest Culprit — Texture Compression

Textures take up the vast majority of VRAM. A single 8K texture set on a Genesis 9 character can completely tank a mid-range GPU.

1. Go to the Render Settings pane and navigate to the Advanced tab.

2. Look for the Texture Compression thresholds.

3. Change the Medium Threshold and High Threshold settings.

   • Recommended: Set Medium to 512 and High to 1024 (or 2048 if you need extreme close-ups).

   • What this does: It forces Iray to compress textures that are further away from the camera while keeping your main subject crisp, saving gigabytes of VRAM.

Step 3: Downscale Background Textures

You rarely need 4K or 8K textures for an environment asset that is 20 feet away from your character or blurred out by depth of field.

1. Select background props in your Scene tab.

2. Go to the Surfaces pane.

3. Look for the Base Color, Dual Lobe Roughness, and Normal maps.

4. Click the thumbnail of the image, select Browse…, note the size, and use an image editor to downscale it to 2K or 1K, or use a DAZ plugin like Texture Compressor if you own it.

5. Alternatively, just remove maps you don’t need for background objects (like high-resolution cutout maps or micro-normals).

Step 4: Master the Power of Instances

If you have a scene with multiple identical objects (e.g., a forest of trees, a crowd of people, rows of chairs), do not copy and paste them. 1. Select your target object.

2. Go to Create > New Node Instance...

3. Duplicate this instance as many times as you want.

• Why this works: DAZ only loads the geometry and textures into the GPU memory once. Ten thousand instances of a tree will take up virtually the exact same VRAM as a single tree.

Step 5: Tame SubD (Subdivision) Levels

High subdivision levels smoothly round out geometry, but they exponentially increase polygon counts right before the render fires.

1. Select your characters or complex props.

2. Go to the Parameters tab and look for Mesh Resolution.

3. Check the Subdivision Level Rendering parameter.

4. Often, figures are set to 3 or 4 for rendering. Dropping a Genesis figure from SubD 4 to SubD 2 can slash millions of polygons from the scene with almost zero visible difference in the final render, unless you are doing a macro close-up of their eyelashes.

Step 6: Memory-Efficient Geometry & Hiding Assets

If it’s not in the camera frame, it shouldn’t be in the GPU.

• Don’t just turn off the “Eye” icon: Closing the eye icon in the Scene tab hides it from the viewport, but Iray might still load it into geometry memory.

• Use Scene Subsets: If you have a massive environment, delete the walls, furniture, and props that are completely behind the camera.

• Instance Optimization flags: For items completely out of view, change their Render Powered setting to Off in the Parameters pane under Display.

Step 7: Optimizing Sub-Surface Scattering (SSS)

Skin shaders use Sub-Surface Scattering to look realistic, but SSS calculations are memory and compute-intensive.

1. If you have background characters, select them and go to Surfaces.

2. Find the Lighting Model or SSS settings.

3. Turn down the SSS amount, or switch their skin shader to a simpler plastic/matte shader if they are far away. They will still look fine in the background light, and your VRAM will thank you.