SoGVRFirstHitAmbientOcclusion

InventorModule

genre	VolRendExtensions
author	MeVis Medical Solutions AG
package	MeVisLab/Standard
dll	SoGVR
definition	soGVR.def

Purpose

The SoGVRFirstHitAmbientOcclusion module adds ambient occlusion to the first hit ray caster, see SoGVRFirstHitRayCastSettings. The ambient occlusion is implemented as described in GPU-Based Monte-Carlo Volume Raycasting by Christof Rezk Salama. The module casts a number of rays on the hemisphere of each hit point, directed towards the gradient of the hit point and calculates how many rays are occluded. Occluded regions are thus darkened.

Usage

The module needs to be added to a SoGVRVolumeRenderer scene, make sure that a SoGVRRayCastSettings and a SoGVRFirstHitRayCastSettings are part of the scene.

Details

(left) Example rendering with ambient occlusion (right) First hit rendering without ambient occlusion

Windows

Default Panel

Output Fields

self

name: self, type: SoNode

Node to be placed in front of a SoGVRVolumeRenderer, make sure that a SoGVRRayCastSettings and a SoGVRFirstHitRayCastSettings are part of the scene.

Parameter Fields

Field Index

Enabled: Bool

Noise Scale Factor: Integer

Num Ray Steps: Integer

Num Samples: Integer

Ray Step Size: Integer

Visible Fields

Enabled

name: enabled, type: Bool, default: TRUE

If checked, the ambient occlusion is enabled.

Num Samples

name: numSamples, type: Integer, default: 32

Sets the number of occlusion rays that are sampled.

Num Ray Steps

name: numRaySteps, type: Integer, default: 10

Sets the number of steps that each ray is casted.

Ray Step Size

name: rayStepSize, type: Integer, default: 3

Sets the step size of each ray (as a multiple of the step size provided by the sampling rate).

Noise Scale Factor

name: noiseScaleFactor, type: Integer, default: 333

Sets the scale factor for sampling in the noise texture, depending on the volume position.