you should carefully read E.2 section in cuda programming guide to understand how filtering works in detail.
The only reason I can see when you would want to add 0.5f to non-normalized texture coordinates (or 0.5/texdim in case of normalized addressing) is to get exactly the value of that sample regardless of interpolation mode set. If you do not add 0.5, then you will get (T[x-1]+T)/2 with linear interpolation. Again, section E.2 explains the details.
i don’t want interpolated values, i want the exact values at the coordinates (x,y,z), and i read in multiple posts, that people would address them with adding 0.5f to each coordinate…