> For the complete documentation index, see [llms.txt](https://docs.d5render.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.d5render.com/user-guide/lights/why-is-there-a-distinct-boundary-between-light-and-dark-in-the-scene-after-using-rect-strip-lights.md).
# Why is there a distinct boundary between light and dark in the scene after using rect/strip lights?
the light overlaps with the top surface
This phenomenon may occur if the rect/strip light overlaps with the model; please adjust the position of the light source slightly to get the normal effect.
the light moved down slightly, do not overlap with model