Ah, interesting! Thanks Tom.  However, I am trying to wrap my head around how I would scatter points into a 2D image/tensor – it looks like scatter only scatters along a single dimension.
If I can figure that out, then actually have floating point “indices” that I want to accumulate in a tensor.  I suppose I could do a bilinear interpolation myself and then add them, unless you know of another function that would do that.