Use of Specular in PBR

Hi all, and apologies in advance if this question has been asked before, I know it’s an old chestnut by now.

So, I’ve been working on a project in UE4 for around 6 months, and during that time have seen many posts stating that we should not mess around with specular values for PBR materials. Leave it at default will be fine for 99% of materials.

So imagine my surprise when I took a look at the open world demo map and see that there are settings on the master shader to clamp spec to 0.01 min to max 0.4. These are all natural materials like earth, wood, and stone.

I’ve been struggling for a while with materials looking ‘tinny’ and overbright and have always put that down to the lighting in game. We have to use 100% dynamic lighting so using AO in shaders is not an option. We use albedo, rough, and normal maps, no spec.

My question is should I go down the route of adding similar spec tweaks to our shaders or is there a better way to go about this and make the materials look more believable?


Well specular in UE4, from my understanding, is hard coded to 0.04 (with 0 metallic), most non-metals fall around that number +/- .02. Are there certain materials you are making that took too tinny? There’s not reason avoid to using specular when you need to, especially as a final touch, but I wouldn’t make a texture for it, or start playing with the value until the polishing phase.