Materials Support and Tips

[Drongle McMahon]

Did some experiments.

The interactions between the colours of the light, the diffuse colour and the colour in that thing under the slider (spec colour?) are not quite what I expected. Basically, the incident light and the diffuse colour are additive - so, for example, if you shine pure blue onto yellow, you get white specular highlights. Only by shining them on a black surface do you get the same colour highlight as that of the incident light. Then the spec colour seems to act as if it is a filter that acts on the incident light before it is added to the diffuse colour. So highlight colour = incident light, filtered by spec colour, then added to diffuse colour. The result of all that is that a lot of combinations give you nothing. For example, if you shine red, green blue and white lights on a red surface, with the spec colour set to green, you get the following (* = filtered by, pure colours).

red * green = black : black + red = red = diffuse colour, so no highlight.

green * green = green : green + red = yellow, so yellow highlight.

blue * green = black : black + red = red, so no highlight

white * green =green : green + red = yel;ow, so yellow highlight.

Now that's fairly simple. Using mixed colours, with different saturation, it often seems to give unexpected effects, especially cases where there are no highlights at all. Oh dear. It's going to be very complicated to control these effects. One of the problems is that RL colours are not simple additive RGB. The same colour can have very different spectral composition different. So we can't expect the simulated effects to be reliably close to RL, even though the end point is detection by RGB sensitivities of receptors in our eyes.

With a horizontal white surface, you get very no highlights at all in daylight because the surface is already saturated white. Add a little grey, and you can see the highlights.

[Coby Foden]

I played a bit with ice texture, trying to create convincing ice cube look with materials.

It's not perfect, but the ice cube with materials definitely felt colder to sit on.  :matte-motes-big-grin: :smileytongue:

I made four prim cubes, each just a tad bigger than the one inside it. Every cube has materials, every cube has transparency, the outermost cube is 78 % transparent, it has also a tad of glow. This cubes layering added a bit more realism compared to a single cube.

Then for each cube I played with the "Glossiness" and "Environment" spinners. Each cube has different settings for those.

With mesh combined with materials it will be possible to create nice icy looking stuff.

PS.
Just sunlight at 2 pm, no local lights.

[TatianaDokuchic Varriale]

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Coby Foden wrote:

 

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Brrrrrr ... makes me cold just looking at you!!  Nice job

[Madeliefste Oh]

Updating an existing product or not?

Since I'm over my first prejudices about materials, I have become enthousiastic, and think about updating older products. I had the idea that my 4 icecubes mesh could profit from the material options.

I tried several things, but I don't like what comes out. Nor in sunlight, nor with local lights the results are satisfying.

I think it has to do with two things. The shape and the color.

The shape: The sides of the cubes are very flat, they are just cubes with corner bevels. The upper faces don't point in the same direction, but are all a bit different rotated. When you let one light source interact with the object, it lights only one face. So you need more lights from different directions to get your highligts all around.
But that brings in the next problem: the color of the diffuse map is almost white. To highlight white you need a lot of light, because white by nature reflects all ready almost all light. In fact you need to over light it, to get any shininess out of it. That doesn't make the overall result better. 

My conclusion is that I'm not going to update this product. In my opinion the diffuse texture looks best without further material additions.

But I wonder did anyone of you experiment with almost white textures and materials? Someone around who managed to produced for example a realistic white porcelain or a realistic white plastic? I have the idea that it might work better with rounded shaped then with flattened shapes... but I'm curious to hear about experience with shininess on white and off-white textures.

 

[Drongle McMahon]

I think ice will always be hard to do dynamically. Its appearance really depends on refraction and internal reflection, including reflections from internal cracks and tiny air bubbles. This gives a much greater variation in directions of light than you can do, probably even with ray tracing. So I guess your statically rendered lighting can get something nearer the truth.

[Pamela Galli]

I tried a floor. In sunlight, no effect. With a light on it, shiny and bumpy. Maybe I have the wrong windlight.

[Aquila Kytori]

 I found that with the floor  textures I was experimenting with today  that the best effect I could get was with lots of Glossiness,very little or no Enviromental shine and with the Specular Colour set to a reasonablly dark grey colour :

 

[Pamela Galli]

Thank you Aquila, that looks good. I will try that.

[Creator Linden]

Thanks for your feedback, Drongle. Those are good suggestions for future viewer releases. For the time being, we will point users to the Physics Optimization wiki. If you have suggestions for this page, please let us know!

And for those who are anxious to try out fixes to some of the issues mentioned on here, we have posted an updated Project Viewer. Please give it a try and let us know if you find any new issues by filing a MATBUG JIRA.

[Jenni Darkwatch]

Just a little heads up for Gimp folks:

It's pretty easy to add normal maps for existing textures. The two most useful plugins there are these, IMO:

Gimp Normalmap: http://code.google.com/p/gimp-normalmap/

InsaneBump: http://registry.gimp.org/node/28117

The latter also generates specular maps for you. The plugins are both not entirely intuitive to use but are actually quite capable for adding normalmaps and/or specular to existing textures.

[Sy Beck]

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Jenni Darkwatch wrote:

Just a little heads up for Gimp folks:

It's pretty easy to add normal maps for existing textures. The two most useful plugins there are these, IMO:

Gimp Normalmap:

http://code.google.com/p/gimp-normalmap/

InsaneBump:

http://registry.gimp.org/node/28117

The latter also generates specular maps for you. The plugins are both not entirely intuitive to use but are actually quite capable for adding normalmaps and/or specular to existing textures.

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Just to add that for Photoshop users  nVidia have a free normal map plugin for PS.

https://developer.nvidia.com/nvidia-texture-tools-adobe-photoshop

[Ciaran Laval]

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Pamela Galli wrote:

I tried a floor. In sunlight, no effect. With a light on it, shiny and bumpy. Maybe I have the wrong windlight.

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Try the four main day cycles, one will probably work quite well and then take it from there messing around with the spinners.

 

[Kwakkelde Kwak]

One tip that can help to reduce texture load, is to take advantage of the sharpness of lossless textures.

As long as the orientation of the deep creases is mainly perpendicular, like floorboards or bricks, you can easily get away with a lossless 64x64 or 128x128 normal map. I'd recommend using bricks or boards 1/8th of the texture size, so a 512x512 diffuse map would have bricks 64 pixels high, on the 64x64 normal map the bricks would be 8 pixels high.

It might sound stupid, but in a lot of cases you'll get nice results if you paint the normal map by hand. It does take some time to figure out the different angles, but you'll get very sharp results, much easier than with all the plugin filters.

One thing I am really missing is this: If I texture objects in SL, I often use the eyedropper. It would be very nice if SL picked for example the normal map of another face if that's what you're working on. Now the eyedrop tool always picks the diffuse map.

[Drongle McMahon]

"It would be very nice if SL picked for example the normal map of another face if that's what you're working on. Now the eyedrop tool always picks the diffuse map."

Oh yes please ... maybe shift-eyedropper to copy all three maps plus shiny spinners, offsets and repeats? That would be a big timesaver.

[Sy Beck]

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Drongle McMahon wrote:

"It would be very nice if SL picked for example the normal map of another face if that's what you're working on. Now the eyedrop tool always picks the diffuse map."

Oh yes please ... maybe shift-eyedropper to copy all three maps plus shiny spinners, offsets and repeats? That would be a big timesaver.

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Gets my vote!  Now what about Ctrl Shift eyedropper, Ctrl Alt eyedropper and Ctrl Shift Alt eyedropper while we're at it for a complete feature set?

[Drake1 Nightfire]

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BlackMagi Darkwatch wrote:

Ok, just started with materials and have to say (using a plugin to generate the normal maps from a texture in Gimp) I’m really pleased with the effect. The only drawback I can see at this time is that in Ultra setting with AO enabled the textures appear really dark to me.  I wander around in Mid/High setting normally.  I added a couple of slow moving light objects to the scene and hey presto – the impression of old stone in 3D!

 

Black

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Where did you find this plug in? Please share as i am havig a hell of a time making a normal map..

Thank you!!

Drake

ETA

I am an idiot for not reading the whole thread first.. Thank you Jenni!!!

[BlackMagi Darkwatch]

Hello Drake

 

The original reference to the gimp plugin I was using before Jenni (thank you Jenni) mentioned insane was from the good building guide here:

http://wiki.secondlife.com/wiki/Case_Study_-_Example_wood_crate_using_materials .

My interest in using materials was sparked from this tutorial at blender cookie:

http://cgcookie.com/blender/cgc-courses/creating-a-sci-fi-panel/

 

Black

[Pamela Galli]

Can someone explain the difference between glossiness and environment?  And what effect making the numbers larger or smaller has on each?

[Vick Forcella]

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Pamela Galli wrote:

Can someone explain the difference between glossiness and environment?  And what effect making the numbers larger or smaller has on each?

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The one increases, decreases the depth of the normal map. The other the reflective value of the specular map.

[Coby Foden]

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Pamela Galli wrote:

Can someone explain the difference between glossiness and environment?  And what effect making the numbers larger or smaller has on each?

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Glossiness:

Increasing the value - brightens the shininess and at the same time makes it "sharper" (i.e. smaller shine area)

Decreasing the value - dims the shininess and makes it spread in a larger area

Environment:

Increasing the value - more reflection from the environment

Decreasing the value - less reflection from the environment (0 = no environmental reflection)

Easy way to actually see what those values do:

Rez a sphere, apply blank specular map and play with those values.

 

 

[Pamela Galli]

Thank you both :-)

[Drongle McMahon]

More - It there is a specular exponent (glossiness = sharpness of highlights) map in the nomal map alpha channel, the value in the glossiness spinner acts as a multiplier for the map's value glossiness at each point. Smilarly, the environment spinner acts as a multiplier for the evironmental reflection mao in the alpha channel of the specular map, if it's there. If those alpha channels are absent, theyare effectively all white (= highest possible value).

More more - the specular reflection is added to the diffuse reflection. It can sparkle if it gets too high. In contrast, increasing environmental reflection reduces the diffuse reflection. At the maximum environmental reflection, the diffuse texture becomes invisible. (This is like a chrome surface.)

[Pamela Galli]

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Drongle McMahon wrote:

More - It there is a specular exponent (glossiness = sharpness of highlights) map in the nomal map alpha channel, the value in the glossiness spinner acts as a multiplier for the map's value glossiness at each point. Smilarly, the environment spinner acts as a multiplier for the evironmental reflection mao in the alpha channel of the specular map, if it's there. If those alpha channels are absent, theyare effectively all white (= highest possible value).

More more - the specular reflection is added to the diffuse reflection. It can sparkle if it gets too high. In contrast, increasing environmental reflection reduces the diffuse reflection. At the maximum environmental reflection, the diffuse texture becomes invisible. (This is like a chrome surface.)

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Thank you -- I did not understand all of that (diffuse reflection?) that but I have copied it and pasted it in the notebook I am keeping about materials, and I am sure if I keep reading it I will understand it.  (I have several other posts by you in the notebook.)

[Drongle McMahon]

Unless an object emits light, all you see is light from other sources reflected from its surface. Diffuse reflection is light that gets scattered equally in all directions, after having its colour changed by the diffuse map . The diffuse map is just the texture we have been used to used before advanced lighting. The amount of diffuse reflection is affected by the angle of the surface to the incident light, but not very strongly.  The diffuse map is the old texture. Old textures didn't have any other kinds of reflection except the old shiny.

Specular reflection is additional reflection of light from light sources falling directly on smooth surfaces. It only appears when a light source and a camera have the approximately same angle to the normal of the surface. The accuracy of the angle required for reflection depends on how polished the surface is. It is modelled by the glossiness parameter and the map in the alpha channel of the normal map. Its colour and intensity are not affected by the diffuse texture, but by the rgb channels of the specular map instead (as well as the colour selector under the spinners).

While specular reflection comes light falling directly on the surface, environmental reflection is an attempt to represent the reflection of indirect light from the sky. It depends much less on the camera angle because it comes from all round instead of from a light source. So it makes the whole surface look wet or polished. It is more or less the same as the old shiny, but with much greater control. At midnight, when the sky is almost completely dark, you don't see the environmental reflection. As far as I can make out, indirect light from light sources you place near an object is not included in the environmental reflection. So you still see only the diffuse and specular reflections. At least for now, indirect light from light sources falling first on the ground or on other objects is not included.

 

[Pamela Galli]

Thank you Drongle :-)