Displaying volumes with volshow

The function volshow can display Medical Volumes directly in live scripts. It's a simpler and faster way to display volumes without launching a separate app like the Medical Volume Viewer.

mmSetUnitDataFolder(3) % cd to unit3 folder
intMV = medicalVolume("CTACardio/CTACardio Crop.nrrd") % load intensity volume as a medicalVolume
volshow(intMV)

medicalVolumes displayed with volshow are transformed into Anatomical Space (LPS). Notice that by default, volshow creates a 3D viewer with a blue background and a black gradient.

You can right-click on the volshow window to bring up a contextual menu with additional options, such as displaying a scale bar or voxel info.

If you uncheck "Always embed Viewer in Live Editor", volshow will display the volume in a separate figure.

Manually adjusting the figure background and render style

If you want to modify the background, you first need to create an empty scene using viewer3D. Here we create a viewer with a white background and no gradient.

hvr = viewer3d(parent=uifigure,BackgroundColor="white",BackgroundGradient="off",CameraZoom=1); % set background color to white and turn off gradient
hvs = volshow(intMV,parent=hvr);

You can adjust the rendering style by modifying the RenderingStyle field in the volshow handle:

hvs.RenderingStyle = "GradientOpacity"; % volshow handle
hvs.GradientOpacityValue = .1; % additional setting for Gradient Opacity

Comparison of Rendering Styles using volshow

We can also modify the Colormap and add a title by modifying the respective fields in the volshow and viewer3d handles, respectively:

hvs.Colormap = parula; % volshow handle
hvr.Title = "CTACardio" % viewer3D handle

Customizing the Render using mmSetVolShowColors

mmSetVolShowColors is a utility function for volshow that simplifies the customization of the display. It automatically changes the background color of the volshow background to white and the applies a Medical alphamap and colormap to the volume render. The alpha- and colormaps are the same options available in the Medical Volume Viewer

To use, first display a volume using volshow and then simply input the handle from volshow into mmSetVolShowColors.

hvs = volshow(intMV);
mapName = mmSetVolShowColors(hvs)

The function displays a list dialog with a choice of alphamap presets.

Select an alphamap to apply.

Here we apply the lung alphamap and colormap.

Overlaying label volumes

Label Maps (or segmentation volumes) can be added as additional elements to the volume rendering using the following syntax:

segMV = medicalVolume("CTACardio/Salcedo Segmentation.seg.nrrd"); % load label map
hvs = volshow(intMV,...
    OverlayData=segMV.Voxels, ... % add label volume
    RenderingStyle="GradientOpacity", ... % change rendering style
    OverlayAlpha=0.4); % adjust overlay transparency
hvs.Parent.BackgroundGradient = 'off'; % modify parent properties (viewer3d)
hvs.Parent.BackgroundColor = 'white'; % modify parent properties (viewer3d)