The 3D Chromosome Browser in gedmatch can be useful, but is visually quite awkward to read. It is a visual presentation of data in your gedmatch lists. DNA Painter enables you to decide which matches you want to paint in and assign groups of matches to common ancestors. The overlay function makes it easy to drill back and split the segments down as you assign them to each generation of ancestors. Take a look at the video about DNA Painter to get an insight into how it works. I use both tools, but find DNA Painter more helpful in my research.