Rendering/PBR/Parameter Maps

Parameter Maps (PRM) is Sonic Team's designation of choice for the texture maps used to represent different PBR material attributes in Hedgehog Engine 2 games.

How the PRM is laid out depends on the game and the shader used by any given material.

Mario & Sonic at the Rio 2016 Olympic Games

son_body_prm

Red Channel, Green Channel, Blue Channel and Alpha Channel (son_body_prm)

In this PRM layout, the red channel of the PRM is the Specular Map, the green channel is the Smoothness Map (opposite of roughness), the blue channel is the Ambient Occlusion Map and the alpha channel is the Cavity Map*.

Areas with a value of or above 90 (out of 100) in the red channel of the PRM are considered completely metallic by most shaders.

*just a guess at the moment, hasn't been confirmed

Sonic Forces

chr_sonic_body_prm

Red Channel, Green Channel and Blue Channel (chr_sonic_body_prm)

In this PRM layout, the red channel of the PRM is the Specular Map, the green channel is the Smoothness Map (opposite of roughness) and the blue channel is the Ambient Occlusion Map.

Areas with a value of or above 90 (out of 100) in the red channel of the PRM are considered completely metallic by most shaders.

MCommon Shaders

chr_silver_cloth_prm

Red Channel, Green Channel, Blue Channel and Alpha Channel (chr_silver_cloth_prm)

This PRM layout is the same as previously mentioned, just with an added Metallic Map in the alpha channel.

Sonic Frontiers and Shadow Generations

chr_sonic_cloth_prm

Red Channel, Green Channel, Blue Channel and Alpha Channel (chr_sonic_cloth_prm)

In this PRM layout, the red channel of the PRM is the Specular Map, the green channel is the Smoothness Map (opposite of roughness), the blue channel is the Metallic Map and the alpha channel is the Ambient Occlusion Map.