You can ignore the influence of the group, select the surface directly according to the material, and hide other unselected objects without destroying the organizational structure in the model.Note: you can't choose the opposite material!
When several objects are overlapped, it will be difficult to select objects. At this time, activate the pick it plug-in, right-click the selection point, and the objects that can be selected will be listed in the right-click menu. At this time, the objects can be selected by name
The plug-in has several function options, which can quickly arrange the outer edge of the surface to the specified elevation. This is an effective tool to make slope, road and irregular surface quickly.