Placing a character on a rolling terrain
To place a single object, you do not need to select it first. When this tool is active, clicking an object selects it and dragging the mouse moves it. The contact point with the underlying surface is, by default, the object's pivot. To use the object's base as the contact point instead, turn on Use Base As Pivot (see following).
As you drag an object, its orientation can change, based on the normal of the underlying surface and the Object Up Axis setting. So, for example, with the default +Z setting, the software continually aligns the object's local Z axis with the underlying surface normal, rotating the object along with its local axis. In general, this setting preserves the moved object's "right-side-up" orientation in relation to the underlying surface.
The Placement Settings dialog provides controls for modifying object movement when using Select And Place. To open the dialog, right-click the (Select And Place) button on the Main Toolbar.
For the purposes of this control, "base" is defined as the point on the object at which the "bottom" end of the specified Object Up Axis intersects the object surface. For example, a sphere's pivot is located at its center by default. So if you use Select And Place to position a sphere on another object, the bottom half of the sphere will fall under the object's surface because Select And Place uses the center as the base. But if you turn on Use Base As Pivot and set Object Up Axis to +Z (the default), Select And Place uses the intersection of the local -Z axis and the sphere's surface as the base instead.
Several key controls are available while using Select And Place:
You can place several objects at the same time either by selecting them before activating Select And Place, or by selecting additional objects while holding Ctrl when Place mode is active. Each object moves according to its own pivot, unless objects are linked.