Here's an equivalent using Observable Plot: Plot.plot({ height: 400, width: 500, color: { legend: true, label: "intensity", scheme: "viridis", type: "linear" // alternatively use {typed: true} in the .csv() call }, marks: [ Plot.rect(surface_plot, { x: "x", y: "y", fill: "z", interval: 5, inset: -0.5 }) ] })

Thank you Fil. I have updated my notebook accordingly.

merci !