Thanks Julien for your clear explanation. Is this somehow also related to the other problem of volume rendering with transparent objects? rendering problems when volume and surface source are added in the same scene
Volume rendering is what makes VTK.js distinct from other online 3D packages, e.g. three.js, Correct and robust volume rendering should be its essential feature not just for the value of the package but also the great expansion of the potential applications. I strongly suggest VTK.js team make this one of the top priorities.