Specifying points in three-dimensional space is essential in AR applications. Geometric triangulation is a straightforward way to specify points, but its naïve implementation has low precision. We designed two enhanced geometric techniques for 3D point marking: VectorCloud, which uses multiple rays to reduce jittering, and ImageRefinement, which allows 3D ray refinement to improve precision. Our experiments, conducted in both simulated and real AR, demonstrate that both techniques improve the precision of 3D point marking, and that ImageRefinement is superior to VectorCloud overall. These results are particularly relevant in the design of mobile AR systems for large outdoor areas.