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Specular map not working?


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Hi everyone, I've been searching for quite awhile now and specular maps seem pretty straightforward at first, but everytime I apply one, it just has no effect. If I use a basic default wood plank diffuse material, and then make a black and white striped image in Photoshop (png) then apply that in the shininess specular window, shouldn't I have shiny stripes on the wood? Does the specular image have to be saved in a certain format or can it just be a .jpeg? Thank you very much for any help :) Rainy

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The colours in the specular (Shininess) map are only part of the control of specular reflection. They dertermine the colour and overall intensity. There is also the combination of the Glossiness spinner and the specular exponent map in the alpha channel of the normal map. The Glossiness/255 multiplies the value in the exponent map to produce the a number than controls the angle over which the reflection is spread. Low values give lower intensity wide angle reflection, while high values give intense reflections over a small angle. In the latter case, you have to get the incident light and camera at just the right angles to see the highlights. It can be difficult with only sunlight, but easier to see with a light source nearby. If the value is zero, then there is no specular reflection. On top of that, the reflection is filtered by the specular map to modify colour and intensity of reflection, and by the specular colour set below the spinners. To keep it simple, use no normal map or one with white or no alpha (fully opaque). Then the exponent (sharpness of reflection) will be uniform and controlled just by the Glossiness spinner. Then apply your specular map and look at it from a direction where you expect the sun or local light to be reflected. Play with the Glossiness spinner to see the effect. It's much easier to see with a sphere, because some part is usually at the right angle. Look at the effect of using the Default normal map as well as the blank normal map.

ETA: and if you are using Firestorm, turn off SSR.

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Thank you very much Drongle McMahon, I've been reading your reply to Lisa Marie back in 2013, your example is beautiful and I was trying to replicate your mini tutorial all day, but I can't seem to be able to do it. Whenever I add my black and white striped specular map texture I should see shiny stripes, right? I have tried adjusting the Glossiness and enviornment but nothing is happening. I will spend the rest of the night trying to understand your reply since it's quite a bit over my head. But again, I don't need a normal map, right? Thank you soooo much for trying to help me :) Also I did try a sphere, but I still couldn't see any reflections.

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The specular map does not need to have alpha. The specular map can be black and white, it can be gray scale and it can be also coloured one.

For example for metals (copper, gold) you would use colour specular map. For colour specular map you can make one from the diffuse map; just make a copy of the diffuse map, make it a bit lighter and use it as a specular map. Then the specular reflections will have the colour of the metal just like it should be.

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I take it for granted advanced lighting is on:)

Then take a look at you wind-light setting.
If it is set, as recommended by some skin makers, with no sun light and no moon light and only ambient light and you have no local point lights, then you will see no glossiness at all no matter how much you fiddle with specular settings.

Choose a standard wind-light setting like A-9AM with good strong sunlight

:smileysurprised::):smileyvery-happy:

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Yes, the default Windlight setting gives pretty good specularity. Also if there are some local lights about then the specularity works well. There are many smooth Windlights, which enhance the avatar's looks; those give no specularity at all.

In the picture below, there is one similar fireplace in front of the avatar as those two fireplaces at the background. In my outfit there are no baked higlights at all (except for the skin). The bra has specularity, the bangle has specularity, the loin cloth has slight specularity as well as the top rings of the anklets.

Specularity is pretty cool when the lighting is right.

PS.
On the outfits I have used coloured specular maps (made from the diffuse map just turning it a bit lighter). I have noticed that if the specular map is gray scale then the local lights will fade away the colour of the diffuse map to a great degree, which does not look natural. Gray scale specular map is especially bad with local lights in clothing where the glossiness is kept low. Colour specular maps work well with the sunshine as well as with local lights.

Specularity-2.jpg

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does that mean that my specular map must have alpha also?

No. If it has no alpha, it will behave as if it has a completely white alpha. The alpha channel of the specular map controls the environmental reflection. As others have said, and I forgot to mention, you have to have Advanced Lighting turned on!

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Drongle McMahon wrote:

There is also the combination of the Glossiness spinner and the
specular exponent map in the alpha channel of the normal map
. The Glossiness/255 multiplies the value in the exponent map to produce the a number than controls the angle over which the reflection is spread.

I have never quite understood what exactly the alpha channel of the normal map does to specularity.

http://wiki.secondlife.com/wiki/Material_Data says:

"Glossiness:

This controls the “glossiness”, or the roughness, of the reflected light on a surface. The lower this value is, the “rougher” the light reflectance is, while the higher the value the “sharper” the light reflectance is. When the normal map’s alpha channel is present, the specular exponent map contained in it is modulated by this parameter."

 

Unfortunately, I'm not any wiser by that statement either. What normal map's alpha channel does to the specularity is still a mystery for me. What more does it do to specularity what cannot be achieved by the specular map itself, I wonder?

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Coby Foden wrote:


Drongle McMahon wrote:

There is also the combination of the Glossiness spinner and the
specular exponent map in the alpha channel of the normal map
. The Glossiness/255 multiplies the value in the exponent map to produce the a number than controls the angle over which the reflection is spread.

I have never quite understood what
exactly
the alpha channel of the normal map does to specularity.

says:

"
Glossiness:

This controls the “glossiness”, or the roughness, of the reflected light on a surface. The lower this value is, the “rougher” the light reflectance is, while the higher the value the “sharper” the light reflectance is.
When the normal map’s alpha channel is present, the specular exponent map contained in it is modulated by this parameter.
"

 

Unfortunately, I'm not any wiser by that statement either. What normal map's alpha channel does to the specularity is still a mystery for me. What more does it do to specularity what cannot be achieved by the specular map itself, I wonder?

The normal map's alpha is multiplied with your glossiness value, in the same way the spec map's alpha is multiplied with the environment value. If you're making a surface of one kind of substance - shiny metal for instance - then the added control of a glossiness alpha is unnecessary. If you're making, say, a polished wooden door with metal hinges, then you'd want different specular settings for different materials. In this case you might have a fairly bright specular map with a high glossiness value, but with a partially transparent (grey) alpha in your normal map for the wooden areas - the metal and wood would be equally 'shiny', with the metal being more glossy.

 

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The map in the alpha channel of the normal map controls the specular exponent. That is the same thing that is controlled by the Glossiness spinner. In fact the value at any point is (Glossiness/255)*(map_value/255). The specular exponent is more or less the inverse of the roughness in physical-based rendering. If the exponent is 1, then all there is no spreading of the angle of the specular reflection. It's like a perfectly reflective surface, a mirror or chrome, with very sharp highlights. As it decreases, the reflected light gets spread out over a greater angle because of the increasing roughness of the surface, and highlights get more diffuse. The Glossiness spinner gives you overall control, while the map allows you to add spatial variation. The specular map doesn't affect the scattering angle at all. It only affects the intensity and colour of the specular reflection.

Here is a picture of some spheres. They all have the same blank texture and completely flat normal map and a white blank specular map with no alpha channel. The first four have no normal map alpha (blank normal map), equivalent to completely opaque (white) alpha channel. Their Glossiness settings are 0 (no specular reflection at all), 20, 40 and 80. You can see how that sharpens the specular highlight as it increases. The fifth sphere also has Glossiness of 80, but it has a noisy alpha channel added to the normal map. That has added spatial variation to the glossiness, so that some bits have sharper brighter highlights, only visible over a small angle in the middle, and some have the broader, weaker highlights where the map values reduce the glossiness. This is not variation in the normal. That is completely flat.

normalphaeffect.jpg

 ETA Here is an earlier picture which illustrates IvanBenjamin's point. This is just a prim cube with just one material, using all three material maps. The wood, the iron bars and the brass bolt heads all have different glossiness, although there is a single overall Glossiness setting, because they have different values in the alpha channel of the normal map.

crate_2_pic.jpg

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