Object ID colours not "pure"

[briareos_kerensky]

Good day everyone,
I recently moved from Max 2015+mentalray to Max 2020+V-Ray and I'm still adjusting to the shift. One of the biggest problems I've encountered is that the VRayObjectID render element doesn't return pure colours.
The first example I've attached is the OID output of a very simple test scene: the red, green, and blue are not pure 255, but only 187.
The second example is from a more complex scene, and this is where things get a bit weird (well, for what I'm used to, at least): it's a crop from an aircraft render, with the canopy almost pure green but showing transparency; the nose landing gear not pure yellow with the exception of the lights, which instead are pure yellow; the plane is a very dark red; all materials, with the exception of the canopy, are fully opaque; the aircraft is black because its OID is zero.

Is this normal behaviour? How do I get pure R,G, and B from the first IDs?

[hermit.crab]

This is the normal behavior of the ObjectID. The element's idea is to generate a unique color for every object in the scene (based on a certain formula for generating a color). For the second scene, you have, most likely, set the canopy material's refraction to affect all channels, hence the transparency.
If you wish to get pure RGB colors, use the MultiMatte pass. It can use Object and Material IDs, so it won't be a trouble to set it up on your scene.

[briareos_kerensky]

Thanks. The example in the online documentation about the Object ID show pure reds, greens, and blues, so I thought it'd work just like in standard Max/mentalray.