Before creating sketches for the client, she imagines the new layout in her mind, most likely using depictive representation.
Explanation:
A depictive representation refers to a representation of a design thought of by a person through which each part of the representation is used to depict and specify a part of the representation while specifying the distances between it and different parts of the depictive representation.
This is all achieved while preserving the corresponding distances between the other parts of the representation. This fits the description of the representation required for the situation here, encountered by Carly.