3D Renderer - 3dct/open_iA GitHub Wiki

Up to Core widgets.

This widget shows a 3D rendering of the datasets for which this is activated in the dataset list; rendering settings can be adapted by editing the dataset properties in the dataset list; for volumes, the transfer functions used for rendering can be specified in the Histogram widget for the dataset.

Navigation works mainly via mouse, you can:

  • Mouse Drag (Left-clicking and then moving) the mouse rotates the view around the dataset center
  • Shift + Mouse Drag moves the camera angle
  • Ctrl + Mouse Drag rotates the camera around the place where the datasets are shown

If you have multiple datasets that you want to show in context to one another, you can use the 3D Magic Lens.

In the top section of the rendering widget, there is a button bar:

images/renderer-topbar.png

Via the +X/-X, +Y/-Y, +Z/-Z, Iso buttons you can set the camera direction (the renderer typically starts with camera direction Iso). You can also store a screenshot of the current view, or a movie of the rotation of the shown dataset around one of the three coordinate system axes. The rightmost button enlarges the 3D renderer to take up all the space in the current window.

Key Commands

When the 3D renderer window is highlighted (click on it once to highlight it), several key commands are available:

  • 'r' resets the view
  • 'j' switches to joystick navigation mode
  • 't' switches to trackball navigation mode (the default navigation mode)
  • 'a' switches to actor modification mode (a single volume or polygon will be modified through the interaction)
  • 'c' switches to camera modification mode (interaction will again modify the camera perspective - the default modification mode)

When the "Show slicers" mode is enabled (see rendering settings, above):

  • pressing the 'x', 'y' and 'z' keys will switch the cutting direction of the respective axis ('y' will for example switch the slicing direction in the xz-plane).

Settings

images/renderer-settings.png

The orange "R" button in the toolbar provides access to renderer settings (which are applied to the 3D rendering widget), such as:

  • "Show slicers" (default: false) - determines whether the slice axes are also applied in the 3D renderer, meaning that the 3D volume will be cut along each axis at the position currently selected in the respective slicer. Slice direction can be reversed through 'x', 'y' and 'z' keys when the 3D renderer dockwidget has the focus.
  • "Show slice planes" (default: false) - determines whether the planes of the three axis aligned slicers are visualized as colored planes in the 3D renderer
  • "Show helpers" (default: true) - determines whether to show the cube indicating axis directions as well the colored axes and the logo widget.
  • "Show position" (default: true) - shows a red cube indicating the current position of the mouse in the slicer (only updated when "Link Views" option in slicer settings is also enabled!)
  • "Parallel projection" (default: false) - whether the 3D renderer uses parallel projection or the standard perspective projection.
  • "Background top" (default: #7FAAFF), "Background bottom" (default: #FFFFFF) - colors used for the renderer background (gradient from top to bottom).
  • "Use FXAA" (default: true) - whether the 3D renderer should use (fast approximate) anti-aliasing. This will reduce so-called aliasing effects ("stair-case"-like appearance of straight lines).
  • "Linear interpolation" (default: true) - whether rendering should use linear interploation (less block artefacts, but picture can look blurry).
  • "Shading" (default: true) - whether to use shading in 3D volume rendering (light options below are to a large extent only applicable if shading is enabled).
  • "Sample distance" (default: spacing of the image) - distance of rays used for 3D volume rendering (the smaller the number, the more rays are used, and thus the better the image quality, but also the slower the computation).
  • "Ambient lighting", "Diffuse lighting", "Specular lighting", "Specular power" (default: 0.2, 0.5, 0.7, 10) - parameters to the shading/lighting model used for volume rendering
  • "Renderer type" - mode used for volume rendering. Typically you should use Default/GPU renderer, as it is faster, but in some instances, you may want to try RayCastRenderMode.
  • "Slice plane opacity" - the opacity of the planes shown when checking the box for "Show slice planes".