Could someone explain to me why this is happening?

How it should look like
http://cloud.steampowered.com/ugc/595827796558500081/6A28076FDE3C2ADBF233C1D0F3820D6FA0E28178/

How it looks like after taking a few steps forward
http://cloud.steampowered.com/ugc/595827796558502367/DDB9EDDF116DCE5905C20E956D2FF25BBB754596/