Alan,
The small scale of LED lighting heads makes it easier to position the light sources very close to the front of the casework plane.
This is critical to reduce shadowing often caused by direct overhead positioning. The second consideration is "visual modeling" of 3-D artifacts. This can be accomplished by using two lighting sources of different lumen intensity, a primary and a secondary, to lend drama, dimension and clarity to form and detail. I hope my experience is helpful. Ask your lighting consultant for examples of their casework projects.
Heat, proper venting and general light intensity are critical conservation considerations as well.
Good hunting, Ed
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Edward Krent
Museum Experience Consultant
KRENT DESIGN
Sharon MA