when your camera is close you get say 6" x 6" area in a 600 x 600 pixel image (for example)  that gives you a nice closeup of your pattern

when you pull the camera back you now have say 12 feet of scene display and still 600 x 600 pixel image. There may simply not be enough pixels to display the pattern.  By getting only parts of the pattern you get a mess.

Making the image bigger will help. I started with 640 x 480 images and when I went to 1200 x 700 things got better.

Check for distortions in the uv map as well.

Bagginsbill is the one to answer this one I think.