A Look Into The Importance Of Specular And Gloss Maps

As with most everything else in this project, textures are vitally important to nail, especially as a group. We have to ensure that not only do we all stick to a consistent style to the point where we can't even tell who did what, but also that they are historically accurate and to a sufficient quality. Painted textures need to be of a very high standard, and photo textures can't look like they were blatantly taken on a sunny British morning, 260 years after what they are trying to portray. Diffuse maps are relatively straightforward to understand, as are normal maps - what you see is what you get - but speculars are different.

http://www.3dtotal.com/tutorial/texturing_and_lighting/brief_consideration_about_materials/brief_consideration_about_materials_01.php

Having read this and subsequently posting it to the team group page on Facebook, I learned about how much more impressive and realistic colour speculars are when used in conjunction with a gloss map. Where a greyscale specular would only specify how shiny the surface of the diffuse is, and how reflective it would be as a consequence, a colour specular not only does this, but also help to specify what type of reflection it is, and how much of the light is absorbed and reflected off as a different hue. Put simply,the main factor in this is whether or not the material is metal, or imitates metal. This is what causes the hue of the reflected light to change. 
For a conductor, a metallic style material, the specular is the same general hue as the diffuse, but you can tweak the levels slightly based on how your results are turning out. The dielectric materials (stuff that doesn't conduct electricity, most non-metals) are a bit tricker. First you invert the diffuse. The inverted diffuse neutralises the light reflection so that its not just a complete reflection of the light. Again alter the levels, checking how it appears on the model until you're satisfied. The above link goes into much greater detail about this, having R-G-B act on a 1-1-1 style format, where the diffuse and inverse should mostly level out (depending on your material). Again, I'd just be repeating the above link, so read that to fully understand it, he explains it far better than I can.
The gloss map compliments the colour specular. It only needs to be greyscale, and the levels determine how dispersed the light is over the object; typically how matte or shiny it is. A darker value means the light is tighter, resulting in a shinier surface. A lighter value means the light is far more dispersed - less shiny and more matte.

The above image (source at base of image) explains what I've been on about. The metal studs and feet of the chair are brighter diffuses on the specular, and dark on the gloss. Likewise, the leather specular is an altered inversion of the diffuse, and the gloss is mostly neutral, as it looks like worn leather, which was once shiny, but has lost its luster over time.

All of this is important for our scene as having a large number of varied assets that only reflect light on the basis of how shiny it is isn't enough - there will be many assets in the scene of different materials, conductors and dielectrics of all sorts. Having a strong understanding of how materials reflect light correctly, especially in the 17th century (building quality would have been lower, so wood may not be as glossy as today's building wood etc.), is crucial to the verisimilitude of the scene. It's also good for considering how various materials would react with one another as well - a boat recently removed from the water would be very reflective as the water will still be soaking the wood. Compare this to a boat that's been on land all night; the wood will be far more matte and less reflective, and all this requires is a change of the gloss and specular.
I'll discuss with the group if they understand how these work, if everyone's comfortable working with colour for speculars, and whether or not we have the budget for a gloss map on everything (our tutor seemed to imply a colour specular was basically crucial).

- Jamie