The illumination conjecture is a classical open problem in convex and discrete geometry, asserting that every compact convex body K in \(\mathbb {R}^n\) can be illuminated by a set of no more than \(2^n\) points. If K has smooth boundary, it is known that \(n+1\) points are necessary and sufficient. We consider an effective variant of the illumination problem for bodies with smooth boundary, where the illuminating set is restricted to points of a lattice and prove the existence of such a set close to K with an explicit bound on the maximal distance. We produce improved bounds on this distance for certain classes of lattices, exhibiting additional symmetry or near-orthogonality properties. Our approach is based on the geometry of numbers.
