P3D Data Processing

Overview

The P3D tool starts with an empty scene. The user can then create SR or VR objects by loading images and applying the available segmentation techniques. As soon as an object is created, it is displayed in the scene with default properties such as color and transparency. If the appearance of an object is not optimal, its properties can be changed and the scene refreshed until the user is satisfied.

Finally, the composition of the objects will show a meaningful scene which can be interactively explored to understand the spatial relationships of the segmented tissue structures. To this end the scene can be rotated in any direction, zoomed, and objects obstructing the view to deeper ones can be temporarily hidden or set to a high degree of transparency. Furthermore, planes showing the original image data can be added, or volumes-of-interest (VOI). To document meaningful results the current rendering can be saved as a screen capture, or a movie of a rotating scene can be generated. It is also possible to save the current configuration into a protocol file, so that it may be reconstructed from the original data at a later time.

Image Data Requirements

There are situations where objects are derived from a single data set, for example the boundary of a brain tumor and the outer brain contour. In this case the spatial alignment of the generated objects will be inherently correct.

However, if objects from different image series are rendered in a single scene, some requirements must be met to ensure that the objects are correctly positioned in the scene. The positioning rules in P3D are as follows:

The generated objects are positioned relative to the center of the scene volume (i.e. the center of the image volume is aligned with the center of the scene).
For the placement and the size of the objects the pixel size is taken into account.

So if the centers of two image volumes are aligned, objects derived from them can be combined, even if the pixel size is not the same.

Note: To ensure this requirement it is highly recommended to match the studies to be combined in the image fusion tool PFUS, save the fused studies, and use them for the 3D rendering.

When importing virtual reality (VRML) objects generated by other programs this behavior may not be adequate. In this case it can be changed in the P3D tool configuration.

Control Tabs

Along the right border there are two control tabs which group the different functions needed for data processing and image rendering. While they are stacked in practice, the graphics below shows them side by side to provide an overview of the user interface elements.

PXMOD Control Tabs

They implement the following functionality.

Input

Loading of the different images which can be used for segmentation or texturing.
Defining the image color tables, window/level settings, and the current slice/frame of the plane images shown in the scene.
Pre-processing of the images, eg. smoothing, masking, scaling.
Loading a volume-of-interest (VOI) definition for restricting a segmentation spatially, or for rendering VOIs as 3D objects.
Defining the segmentation process.
Defining the 3D rendering type (SR, VR, VR HD) to apply.
Starting the creation of 3D objects.

View

Inspecting the available 3D objects which are organized in a tree structure.
Modifying the properties of each object (color, texture, visibility, etc.) to adjust the scene.
Adding a marker to the scene which highlights an important location.
Adding plane images to the scene.
Adding light to the scene.
Cutting parts out of the objects.
Rotating or zooming the scene.
Recording a movie of a rotating scene.
Saving the SR objects of a scene as a VRML file.
Saving screen captures of the scene.

The procedures to generate and manipulate 3D scenes are described in the next sections.

In This Section

Preparation Steps

Visualization Options