Table C.11.30-1 specifies the Attributes of the Volume Render Geometry Module, which describe the geometry of the volume rendered view.
Table C.11.30-1. Volume Render Geometry Module Attributes
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Position of the viewpoint in volume space. A point (x,y,z) in the Volumetric Presentation State Reference Coordinate System. |
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Point the viewpoint is looking at. A point (x,y,z) in the Volumetric Presentation State Reference Coordinate System. |
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Vertical orientation of the view. A vector (x,y,z) in the Volumetric Presentation State Reference Coordinate System. |
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The field of view specified as a 6-tuple of values (Xleft, Xright, Ytop, Ybottom, Distancenear, Distancefar) in the Viewpoint Coordinate System, in mm. See Section C.11.30.1. |
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The rendering method used during the ray casting compositing operation. Enumerated Values:
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Spacing in mm between samples along each ray in the original volume rendering operation. See Section C.11.30.2. |
The Render Field of View (0070,1606) defines the region of the volume data that is displayed.
The viewpoint is positioned and oriented within the Volumetric Presentation State Reference Coordinate System (VPS-RCS) by Viewpoint Position (0070,1603), Viewpoint LookAt Point (0070,1604) and Viewpoint Up Direction (0070,1605). This position and orientation establish a Viewpoint Coordinate System (VCS), which is a right-hand coordinate system in which the viewpoint is positioned at (0,0,0) and is looking at a point at (0,0,-z) and the up direction is along the +y axis.
Render Field of View (0070,1606) is specified by the following coordinate values in the Viewpoint Coordinate System:
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Distancenear, Distancefar specify the distances from Viewpoint Position (0070,1603) to the near and far depth clipping planes. Both distances shall be positive, and Distancenear shall be less than Distancefar.
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Xleft, Xright specify the coordinates of the left and right vertical clipping planes at Distancefar. Xleft shall be less than Xright.
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Ytop, Ybottom specify the coordinates for the top and bottom horizontal clipping planes at Distancefar. Xleft shall be less than Xright.
Note
Positive values of Distancenear and Distancefar place the near and far rectangles of the field of view on the negative Z axis at Z values of -Distancenear and -Distancefar, respectively.
In the case of a Render Projection (0070,1602) value of ORTHOGRAPHIC, Render Field of View (0070,1606) defines a rectangular cuboid with dimensions (Xright minus Xleft) by (Ytop minus Ybottom) by (Distancefar minus Distancenear), in mm, as shown in Figure C.11.30-1:
In the case of a Render Projection (0070,1602) value of PERSPECTIVE, Render Field of View (0070,1606) defines a frustum in which the far rectangle is larger than the near rectangle. The extent of the far rectangle is established by the points (Xleft, Ytop) and (Xright, Ybottom) at Distancefar. The extent of the near rectangle is established by the four points where rays originating at the viewpoint position to the corners of the far rectangle intersect the plane that is located at Distancenear from the viewpoint, as shown in Figure C.11.30-2.
