An SVG overlay can be added to OpenSeadragon viewer.
Updated missing url https://rawgit.com/fabiovalse/Hub/master/lib/openseadragon/openseadragon.min.js to https://cdn.jsdelivr.net/gh/fabiovalse/hub/lib/openseadragon/openseadragon.min.js
https://d3js.org/d3.v4.min.js
https://d3js.org/d3-selection-multi.v0.4.min.js
https://rawgit.com/fabiovalse/Hub/master/lib/openseadragon/openseadragon.min.js