Switching between orthogonal and perspective modes

You can display 3D models in the IFC Model pane and IFC Comparison Model pane in two different modes:

Orthogonal mode, in which a model is drawn with parallel lines (ie lines that do not converge at a distant vanishing point), meaning that objects remain the same size regardless of their distance.
Illustration of a 3D model displayed in orthogonal mode
Perspective mode, in which a model is drawn as it is seen by the eye, with objects appearing smaller as their distance from the observer increases and with the size of the objects' dimensions along the line of sight being relatively shorter than dimensions across the line of sight.
Illustration of a 3D model displayed in perspective mode

To toggle between displaying a 3D model in orthogonal mode and perspective mode in the IFC Model pane, do either of the following:

On the 4D tab, in the 3D Viewer group, click Perspective Mode.
Right-click the IFC Model pane and select Perspective Mode from the menu that appears.

To toggle between displaying a 3D model in orthogonal mode and perspective mode in the IFC Comparison Model pane, right-click the IFC Comparison Model pane and select Perspective Mode from the menu that appears.

Orthogonal and perspective modes are both useful in different situations:

Orthogonal mode enables you to judge dimensions and proportions more accurately, as each line of 1 unit's length appears to have the same length everywhere in a model. When in orthogonal mode, you can rotate 3D models easily to view them from all available angles.
Perspective mode gives you a realistic impression of what a building will actually look like. It has depth, which makes it easier to judge distances. In addition to this, you can "walk through" a building when you view a 3D model in perspective mode, which enables you to see buildings from the inside.

Note that the actions of the mouse and the controls in the 3D Viewer group on the 4D tab of the Ribbon differ depending on the current display mode, and that you must turn on perspective mode if you want to be able to "walk through" a building.