Issue & Reason
For background, Avizo 3D delivers 3D images through a proprietary C++ codebase called OpenInventor, which relies on OpenGL for scene management.
Running two overlapping Volume Rendering modules simultaneously is not officially supported. This limitation exists because neither OpenInventor nor OpenGL support it. The application normally prevents users from doing this by disallowing the creation of two Volume Rendering modules for the same dataset. Users may attempt to circumvent this restriction to visualize multiple datasets or effects at once. While this is technically possible, it is considered unsupported usage, and may result in suboptimal or incorrect rendering.
Because this configuration falls outside the supported use of the software, no official documentation is provided for this specific scenario.
Suggested Solutions
1. The most common workaround is to use the Volren module. It relies on a different rendering pipeline than Volume Rendering. However, the rendering is less accurate and may not fit your application.
2. Another practical approach is to combine a Surface View or IsoSurface module with a single Volume Rendering module. Some interactions between shadows and transparency may not render correctly. However, this is a practical way to see two datasets at once.
3. You can also use a shared clipping plane between two Volren (or even Volume Rendering) modules.
For detailed instructions, refer to the following resources: How to Set Up a Two-Sided Clipping.
4. If you wish to run two Volume Rendering modules for the same dataset, you can do so using the Tcl console:
- Open the Tcl console by clicking the ">" icon on the lower-right corner of the interface.
- Create an additional Volume Rendering module and its corresponding Volume Rendering Settings module by running the following commands:
- create HxVolumeRender2
- create HxVolumeRenderingSettings
- Two unattached modules will appear in the Project View. Connect the Common Settings port of the Volume Rendering module to the Volume Rendering Settings module.
- Link the Volume Rendering Settings module to the dataset of your choice.
This bypasses the GUI limitations on attaching two or more Volume Rendering modules to one dataset.