Floodlighting should show the undulating contours of different planes and components of an object by using adjacent areas to get more or less illumination or shadows, respectively. In the design of lamps, in order to better play the lighting effect like outdoor floodlights, the following points should be considered in practical application.
It is the shadows that accentuate the undulations of the façade, so the lighting should always provide imaging of the surface, light hitting the façade at a straight angle will not cast shadows and make the surface appear flat. Shadow size depends on surface relief and the angle of incidence of the light. The average illumination direction angle should be 45°. If the fluctuation is extremely small, the angle should be greater than 45°.
For surface lighting to appear balanced, all shadows should be cast in the same direction, and all luminaires illuminating surfaces in a shadow area should be cast in the same direction. For example, if two lights are aimed symmetrically in the vertical direction of a surface, shadows will be reduced and confusion may appear. As a result, surface undulations may not be seen clearly. However, large protrusions can create large, dense shadows, and in order to avoid disrupting the integrity of the façade, it is recommended to provide weaker lighting at a 90° angle to the key lighting to soften the shadows.
Viewing Angle and Lighting Direction
In order to see shadows and surface undulations, the lighting direction should be different from the viewing direction, and the angle between the two directions should be at least 45°. However, for monuments that can be seen from several places, it is not possible to strictly adhere to this rule, the main viewing point should be chosen, and this viewing direction should be given priority in the lighting design.