Edit Views

Views (also named "Cameras" in other programs) determine the part of the scene that will be displayed in an image.

[View Editing Dialog]

View Setup Diagram

This diagram illustrates the properties of the current view. The graphics area represents the possible image area, or a part of it for perspective and parallel views.

The red rectangle represents the area that is covered by the image with the proportions set to the right. The viewing angle of each image boundary relative to the view direction (or its distance for parallel views) is marked at the border of the diagram, also in red.

The light grey crosshair marks the view center or the view direction. Tick marks on the crosshair are displayed every 15 degrees (or 15 units for parallel views), and the outline of each 30 degree frame is shown as a light grey rectangle or square. In the screenshot above, this principle is best seen on the vertical crosshair line. The 60 degree square is also the outline of the diagram.

Image Proportions

This area of the dialog sets the size and proportions of the view. Some of the fields may not be available for all projection types.

Orientation:
Image Aspect:
Those two options together define proportions of the image with respect to it's width and height. If the image aspect is set to square or a free aspect, then the orientation selection has no effect. Otherwise, it will determine if the width or the height of the image is bigger than the other.

Horizontal Opening Angle:
Vertical Opening Angle:
Diagnoal Opening Angle:
Those three values are the angles of the field of vision in horizontal, vertical, and diagonal direction. They determine how much of the "world" can be seen from the specified point of view. If the image aspect is set to a fixed value, then each change here will also modify the respective other two entries, to maintain that aspect.

Focal Length:
The focal length is determined in terms of the standard 24mm slide format. If the images aspect is set to 2:3, then the image shows exactly what a usual photographic camera would show with a lens of this focal length.

Right Shift:
Up Shift:
The shift values move the frame of the image in the specified direction, without modifying any other of the view properties. This can be used to avoid distortions of perspective, eg. when looking up a tall building from a close distance in the street.

Front Clipping Plane:
Back Clipping Plane:
The clipping planes can be used to cut parts of the geometry away, that would otherwise obstruct the view, without actually removing them for the simulation. A typical application is to look into a room outside, by setting the front clipping plane just behind the front wall, or for floor plan views, looking through the ceiling. The distances are measured from thev view point, so that a zero distance will result in no clipping at all, except with parallel projections. For fisheye projections, the view planes are actually view spheres. A negative front clipping plane may cause objects behind the view point to be displayed in inverted view.

View Specification

Projection Types:
There are several ways to project the world into a two dimensional image:

Perspective: The perspective view projection comes nearest to what we usually consider a "natural" view, as it most closely reproduces the way that the human eyes perceive reality.
Parallel View: The parallel view is equal to an axonometry.
Cylindrical Perspective: The cylindrical perspective is also known as "panorama view".
Hemispherical Fisheye: The hemispherical fisheye projects the hemisphere in front of the viewpoint on a circular image plane.
Angular Fisheye: The angular fisheye projects the full environment around the viewpoint on a circular image plane.

View Point:
The view point is where the eye of the viewer is located in the scene for the view.

View Direction:
The view direction defines the central main axis of the view. Points that lie in this direction are displayed in the center of the image, except when an image shift is applied.

View Up Vector:
The view up vector determines the orientation of the image, and is usually equivalent with the vertical axis of the image plane. In most cases, this axis will point towards positive Z, which means that the viewer holds an upright position. Other directions would imply that the viewer tilts his head to one side, a direction towards negative Z will produce an upside down image.

Buttonbar

Ok - accept the edited view configuration and close the dialog.

Cancel - discard the edited view configuration and close the dialog.

Revert - discard the entered values and reset all fields to the values they had when the dialog opened.

Help... - display this information.

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Simulation Setup