In my (very patient) attempt to model a room, certain locators seem to have changed places and appear on top of eachother. Particularly on the floor surface. The room is empty so i placed some stickers on the floor for better calibration. Does this problem relate to ".. Imagemodeler works on color pattern recognition.  If your grid point are all the same color, there's a good chance it's getting confused.." How can I solve this ?

Hi,
 
  At the calibration step there is no pattern recognition. So this is not the cause of your pb. The feature detection and correspondences are made by the user (Marker tool).  
Have a look at http://www.realviz.com/board/viewtopic.php?t=884 , where i tried to summerize some tips for placing markers.
 
Your idea of placing markers on the walls is good, but be sure they are well distributed in 3d (not all in the same plane).  
For rooms, placing a central object that is seen in allmost all shots is also a good help for calibration.
 
Hope it helps,
 
Stef