SoGVRLitSphereShading

InventorModule

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

Purpose

The SoGVRLitSphereShading module implements lit sphere shading, as described in Style Transfer Functions for Illustrative Volume Rendering by Stefan Bruckner. Instead of using a traditional Blinn-Phong lighting model, this model projects the gradient to a 2D sphere in view space. This allows for modelling complex lighting situations or styled rendering by loading different 2D lit sphere images. In combination with tagged volume rendering, a stack of 2D lit spheres can be connected and each tag can use a different lit sphere.

Usage

Just add this module to a SoGVRVolumeRenderer scene and enable the illumination of the renderer. The lit sphere shading then replaces the traditional lighting. The contour mode only works when used together with SoGVRRayCastSettings, since it detects changes in the gradient along the ray.

Details

For more details, read the paper Style Transfer Functions for Illustrative Volume Rendering by Stefan Bruckner or have a look at the example network.

The example network renders a lit sphere using Open Inventor and the OffscreenRenderer:

This image is then used for lit sphere shading:

Tips

For a nice collection of lit sphere images that can be used, use Google image search with search term lit sphere.

Windows

Default Panel

Input Fields

image

name: image, type: Image

2D RGB or RGBA image (or a 3D stack of 2D images), used for lit sphere shading

Output Fields

self

name: self, type: SoNode

To be placed in front of a SoGVRVolumeRenderer.

Parameter Fields

Field Index

Contour Thickness: Float

Enable Contours: Bool

Enable Enhancement: Bool

Enable Lit Sphere Alpha: Bool

Enabled: Bool

Per Tag Lit Sphere: IntegerList

Use For First Hit: Bool

Visible Fields

Enabled

name: enabled, type: Bool, default: TRUE

If checked, the lit sphere shading is enabled.

Per Tag Lit Sphere

name: perTagLitSphere, type: IntegerList, default: 0

Sets a list of per-tag index into stack of 2D lit spheres. This is only used if per tag shading is enabled and the input lit sphere image is a 3D image.

Enable Contours

name: enableContours, type: Bool, default: FALSE

If checked, contour rendering is enabled (see paper for details).

Contour Thickness

name: contourThickness, type: Float, default: 0.2

Sets the thickness of the contours.

Enable Enhancement

name: enableEnhancement, type: Bool, default: FALSE

If checked, the gradient based enhancement is enabled (see paper).

Enable Lit Sphere Alpha

name: enableLitSphereAlpha, type: Bool, default: FALSE

If checked, using the alpha value of the lit sphere is enabled.

Use For First Hit

name: useForFirstHit, type: Bool, default: FALSE

If checked, the lit sphere shading affects the SoGVRFirstHitRayCastSettings lighting instead of the normal lighting.