a)
The central part of image is floor
Assumptions:
1)Floors are normally shiny and reflect significant amount of light.
2)Objects/dirt like clothes,slippers etc cannot lie on wall due to gravity.

The upper left and upper right parts of the image are walls because their projections on this image are 
converging straight lines.There is a change in image brightness as we move from central part to edges.  



b)
The boundaries of the dirt(cloth,shuttle box etc)can be mapped to the grid.The portion inside the resulting
closed curve will indicate the location of dirt in the grid.

c)
Since dirt can be as fine as small particles of dust to aggregrates like clothes/box,a value between 0 and 1
may not be a good choice to map the dirt in each grid.

d)
The robot will collect a number of images to determine its location relative to floor-wall corners and other
objects/dirts.