See http://codepen.io/etpinard/pen/xEVOwZ where odd looking line appear on the surface e.g.  I believe this issue is related to how [`colormap`](https://github.com/bpostlethwaite/colormap) is handling custom colorscale. The `colormap` package is a dependency of the [`gl-surface3d`](https://github.com/gl-vis/gl-surface3d) gl-vis module.