Because the rendering process is not interruptible, after you suspend interaction in sub-sampling mode it may be inconvenient to wait for the full resolution image before resuming interaction. Progressive rendering consists of generating several successive smaller images when the viewer is in sub-sampled mode and becomes still. The viewer progressively displays these images with increasing resolution up to full resolution.

This feature is enabled via the SoPreferences SoPreferences SoPreferences DIRECTVIZ_PROGRESSIVE_RENDERING parameter or SoDirectVizManager SoDirectVizManager SoDirectVizManager progressiveRendering field. The number of steps (intermediate images) is set with the SoPreferences SoPreferences SoPreferences DIRECTVIZ_RENDER_STEPS parameter or SoDirectVizManager SoDirectVizManager SoDirectVizManager numProgressiveRenderingSteps field.