The influence of incidence angles is similar to the other test
tables. The values of σR for concrete decrease from ±0.75mm
(0gon) to ±0.35mm (80gon), for sandstone from ±1.2mm to
±0.75mm, for brick from ±1.0mm to ±0.5mm and for marble
from ±1.1mm to ±0.8mm. An exception is granite where the
values are nearly constant about ±1.2mm.