A volume renderer, made in Unity3D. See slides from presentation here: https://speakerdeck.com/mlavik1/volume-rendering-in-unity3d

• Unity 2018 1.5 or newer (should also work with some older versions, but I haven't tested)

• Open "TestScene.unity"
• Click "Volume Rendering" in the menu bar
• Select "Load Asset"
• Pick a file in the "DataFiles" folder (I recommend manix.dat)
• Click the "import"-button

1. Import model

In the menu bar, click "Volume Rendering" and "Load dataset"

Then select the dataset you wish to import. Currently only raw datasets are supported (you can add your own importer for other datasets).

In the next menu you can optionally set the import setting for the raw dataset. For the sample files you don't need to change anything.

2. Moving the model

You can move the model like any other GameObject. Simply select it in the scene view or scene hierarchy, and move/rotate it like normal.

3. Changing the visualisation

Select the model and find the "Volume Render Object" in the inspector.

Here you can change the "Render mode":

There are 3 render modes:

• Direct Volume Rendering (using transfer functions)
• Maximum Intensity Projection (shows the maximum density)
• Isosurface Rendering

Direct volume rendering is the most standard rendering mode. It sends rays through the dataset, and uses "transfer functions" (1D or 2D) to determine the colour and opacity. Transfer functions map density (2D: also gradient magnitude) to a colour and opacity.

• Modifying transfer functions: Click "Volume Rendering" in the menu bar and select "1D Transfer Function" or "2D Transfer Function"
  • 1D Transfer Function: X-axis represents density and Y-axis represents alpha (opaccity). Move the grey alpha knots to create a curve for opacity by density. Right-click to add new alpha knots. The bottom gradient-coloured panel maps colour to density. Right-click to add new knots and click on an existing colour knot to modify its colour.
  • 2D Transfer Function: X-axis represents density and Y-axis represents gradient magnitude. Click "add rectangle" to add a new rectangle-shape. Move the four sliders (bottom left) to modify size/position. Modify the two sliders to the right to change min/max alpha/opacity. Each rectangle can have one colour (see colour picker).

Isosurface rendering draws the first thing the ray hits, with a density higher than some threshold. You can set this threshold yourself, by opening "DirectVolumeRenderingMaterial" and changing the "Min Val". These can also be used with direct volume rendering mode.

• Create an instance of an importer (for example RawDatasetImporter):
  DatasetImporterBase importer = new RawDatasetImporter(fileToImport, dimX, dimY, dimZ, DataContentFormat.Int16, 6);
• Call the Import()-function, which returns a Dataset:
  VolumeDataset dataset = importer.Import();
• Use VolumeObjectFactory to create an object from the dataset:
  VolumeRenderedObject obj = VolumeObjectFactory.CreateObject(dataset);

See "DatasetImporterEditorWindow.cs" for an example.

The RawDatasetImporter imports raw datasets, where the data is stored sequentially. Some raw datasets contain a header where you can read information about how the data is stored (content format, dimension, etc.), while some datasets expect you to know the layout and format. The importer takes the following parameters:

• filePath: Filepath of the dataset
• dimX: X-dimension (number of samples in the X-axis)
• dimY: Y-dimension
• dimZ: Z-dimension
• contentFormat: Value type of the data (Int8, Uint8, Int16, Uint16, etc..)
• skipBytes: Number of bytes to skip (offset to where the data begins). This is usually the same as the header size, and will be 0 if there is no header.

• DICOM support
• Improve 2D Transfer Function editor: Better GUI, more shapes (triangles)
• Optimise histogram generation
• Support very large datasets (currently we naively try to create 3D textures with the same dimension as the data)
• Volume cross sections