How to remove weird "shadow/light" lines?

Hi guys, i have different rooms in my scene and for the floor i used a lot of wooden boards all close together, with a small gap between each one (that’s an example of my scene : Weird lines! - Album on Imgur).

The problem is that, looking at the image, you will see some white thin lines and i wish to remove them, is there a way to do this?
Thank you, Matthias.

what are we looking at? Those boards all geometry? You have a directional light in there? Does it cast shadows? What material is on those boards: a smooth or rough material? It could be many things, but right now it looks simply like light hitting polygons on the side

That link doesn’t work

Sorry, this is the updated link : Weird Lines - Album on Imgur