The Options menu is as follows:-
|Movie Control||Displays the movie control window|
|Slice Movie Control||Displays the movie control for the threshold window|
|Volume of object||Calculates the volume of the currently displayed object. Tissue below the selected threshold is not included in the volume. The accuracy of this measurement depends upon the selection of an appropriate threshold value.|
|Surface area of object||Calculates the surface area of the currently displayed object. The area of a hollow object includes both the inner and outer surfaces. The accuracy of this measurement depends upon the selection of an appropriate threshold value. The calculation separately displays areas for the rendered surfaces and the cut sections. Incorrect results may occur if the crop controls have been used to edit the object instead of the proper edit facilities,.|
|Painted area||Calculates the area of a region marked on the visible surface. The edit mode can be used to mark a region (without actually editing the data). This can only measure a continuous visible surface and will report errors if it detects a step edge in the surface being measured. This measurement relies upon the screen image and will be more accurate if the feature being measured covers a large fraction of the window and is rendered in HiRes mode.|
|Difference of surfaces||Calculates the shortest distance of each point on one object surface from a second object surface. The two objects must have been created by editing.|
|ZDifference of surfaces||Calculates the distance between surfaces perpendicular to the plane of the screen. This is quicker than the above option but, for surfaces at an angle to the plane of the screen, it can give misleading results.|
|Style||Select interpolation mode, surface/perspective/radiographic , perspective viewing distance, Marker style, cross hair style & threshold style. NOTE: sinc & smooth interpolation modes are ~50x slower than linear!|
|Timing||if tagged, shows rendering time|
|HiRes||if tagged, render at 512*512 resolution, otherwise 256*256. Composite View is affected by the HiRes mode. A depth sorted effect is produced when Hires is not tagged and a translucent effect is produced when HiRes is tagged.|
|Negate data while loading||if tagged, the data will be loaded as a negative with dark parts of the slices bright and the bright parts dark. This allows the thresholding to operate in reverse for imaging the darker parts of the original data.|
|Normal + negated data load||if tagged, the slices will be loaded twice (this doubles the number of slices). The first set will be as normal, the second will be negative (as in the above option). An edit state is automatically set up, which separates the two sets into different objects (0 & 1) and aligns these for mixed imaging. It also sets the threshold style to allow separate thresholding of the two objects.|
This popup allows control of some of the program style options.
The choice of interpolation mode affects image quality, the precision of marker placement and the smoothness of saved depth maps. Linear should be adequate for most practical purposes. Sinc and smooth interpolations are MUCH slower but may give better quality reslicing images depending upon the properties of the loaded data.The smooth option IS appropriate for saving depth maps (Zbuffers) for C.N.C milling control and especially for the creation of stereolithography data for rapid prototyping.
Surface imaging is the default render mode on start up. The threshold window is used to remove all tissue below the selected threshold, allowing viewing of denser tissues. The radiographic mode simulates the generation of a radiograph through the data from the chosen direction. The threshold window is used to remove all tissue above the selected threshold, allowing good renderering of soft tissue detail in CT by removing the dense bone signal. Setting a high threshold still allows rendering of hard tissues. In radiographic mode it is not possible to place markers, back cull, perform 3D editing , compare depth maps or save depth maps.
Rendering defaults to a parallel projection mode (viewpoint at infinity). A perspective view of the surface rendering can be selected. The viewpoint distance edit window will be enabled when perspective is selected, allowing the user to define a viewing distance from the centre of rotation of the viewing window. In perspective mode it is not possible to place markers, back cull, perform 3D editing , ortho reslice , compare depth maps or save depth maps.
Specularity and Depth Enhance allow adjustment of the surface rendering. An increased specularity (default value = 1.0) makes the rendered surface look more metallic. An increased depth enhancement (default value = 0.5) accentuates the sense of depth in the image by darkening the parts of the object further from the viewer.
The threshold setting mode is only significant when the 3d editing option has been used to create multiple objects. These objects are either forced to be rendered at the same threshold or allowed to be set to different thresholds.
Two styles of marker are available when placing landmarks. One is a simple cross, the other provides surface contours which can assist in accurate placement of markers on curved surfaces.
Two styles of cross hair are available when reslicing. One is a set of solid lines, the other provides a small gap at the centre in case the lines obscure the object at the centre of interest.
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