This picture is a called a McGuire Chart. It is a twist on a descendant chart in that it shows how much each person who have done an atDNA (autosomal dna) test share dna between each other. Shared dna (measured in cM) is indicated (as is the relatedness ie. 3C or similar) where the two people cross vertically and horizontally.
Some of you may know that I have been trying to recruit folks to join our Porteous surname project and to transfer their test results from one company to another or to www. gedmatch.com. This is the type of thing that can be developed.
The Chart is primarily descendants of Archibald Porteous and Grizel Robison (#925) but includes a few other folks who are either speculative children of Archibald and Grizel or are descended from branches of the Porteous family #8 (Thomas Porteous and Anne Brown) who I believe my #925 falls under. The three siblings in the middle right are me, my brother and sister. The shared dna lends to this theory until I can get a direct male of that family to test and to come up a match to myself. The chart was generated using matches to my grandfather's 1C W.H. who happens to have the most Porteous cousins as shared dna matches as well as a couple other key matches who also have dna matches to a wide span of my cousins.
Here's a sample of what the site provides, looking only at chromosome 14. All your info in one picture with all the match info included. Very powerful. You can also have it run the tool and tell it to include (highlight in results) matches with a specific ancestral surname so you don't have to search each of your hundreds of matches but only those highlighted in bold.