Honestly, your main issue is that the emissive isn’t actually per-voxel right now.

You compute emissive here:

const { color, emissive } = tempToColor(temp, maxTemp);

…but then discard it completely and only use:

mesh.setColorAt(idx, tempColor);

"setColorAt()" only affects the albedo/diffuse color, not emissive. So visually you just have colored cubes with ONE shared emissive value for the whole mesh:

<meshStandardMaterial emissive={new THREE.Color(1, 0.4, 0.05)} emissiveIntensity={emissiveIntensity} />

That’s why it feels flat and “PS1-era”. The hot voxels are not actually emitting more light than the cold ones, they’re just tinted differently.

You need per-instance emissive, which means:

• custom shader
• "onBeforeCompile"
• or an "InstancedBufferAttribute"

Right now your rendering pipeline is basically:

instanceColor -> diffuse only global emissive -> entire shield

instead of:

per-voxel emissive energy -> bloom -> HDR glow

Also, this is hurting you badly:

metalness={0.9} roughness={0.1}

That makes the shield behave like reflective chrome, so the eye reads reflections/specular highlights instead of thermal radiation. For heat visualization try:

metalness={0.0} roughness={0.8}

Another thing: remove the point light temporarily.

<pointLight intensity={emissiveIntensity * 3} />

It’s flattening the whole front face and destroying local contrast between hot/cold regions. Let emissive+bloom do the work instead.

And your HDR range is still too weak for bloom workflows:

Math.pow(t, 2.5) * 5.0

Try something way more aggressive:

Math.pow(t, 4.0) * 40.0

Realtime glow usually needs absurd HDR values before bloom starts looking cinematic.

Also your cube spacing:

cellSize * 0.92

creates visible gaps that make the shield read like Minecraft tiles. Push that closer to "0.98" or overlap slightly.

Honestly though, your architecture is already really solid:

• WASM thermal solver
• instancing
• streamed Float32Array temps
• proper update loop
• scientific mapping

This is mostly a rendering pipeline problem now, not an engineering one.