The Embryo above is a GMax render, shading in sim will be quite different. I'm wondering if what your talking about is to do with smoothing groups, it's common to apply smoothing to objects, such as wings, control surfaces, etc. This is fine until you apply the same smoothing to a sharp edge on the item, ie. the end plate of a flying surface. Now this should be a sharp edge as in reality it isa smooth surface with the wing. If you apply smoothing to the whole elevator, let's say, in Gmax, it will attempt to round off those edges, hence you get odd shadows round the edges that should be flat.
hope that makes sense, it is a hard thing to get right. Examples with smoothing groups normal and fixed.
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