Maya surface luminance node ignores specular contribution

[AardmanCGI]

Hi,
I am trying to make an iridescent shader by using Maya's surface luminance node to sample the surface luminance and then remap that through a colour ramp. However the node seems to ignore the specular contribution. Is this a bug or is this intended? Is there a way to work around or fix this?
As an alternative I have also tried chaining together several Maya shading nodes (or vray materials) and remapping the output of one through a ramp to the in colour of another. This would work fine in the Maya renderer but also doesn't seem to work in vray.
eg: Labert1.outcolorR->ramp.vcoord:ramp.outcolor->Lambert2.color

Thanks,

Philip

[vlado]

For the moment, the surface luminance shader samples the diffuse surface illumination - it does not have a specular component.

V-Ray does not allow materials to be used as textures and connected to texture slots. You might be able to do something very similar with the V-Ray blend material though.

Best regards,
Vlado