Normal Map & Ambient Occlusion

[AbbyRosseta]

Noob Alert!

I textured my low poly mesh with both a normal map and ambient occlusion but now I'm not exactly sure how to go about texturing the shirt I've created. How would I be able to combine both uv's and texture my shirt in photoshop?

Both uv's are in the same texture tab thinger...not sure if that is the correct way of doing it. Anyways, I would greatly appreciate it if someone would explain it step by step.

 

*Quick Note*: I sculpted the high poly mesh on zbrush and transfered it back to blender along with the low poly mesh in order to create the normal map and ambient occlusion. For those who use zbrush to sculpt, is there a easier way of doing this on zbrush?

[Drake1 Nightfire]

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AbbyRosseta wrote:

Noob Alert!

I textured my low poly mesh with both a normal map and ambient occlusion but now I'm not exactly sure how to go about texturing the shirt I've created. How would I be able to combine both uv's and texture my shirt in photoshop?

Both uv's are in the same texture tab thinger...not sure if that is the correct way of doing it. Anyways, I would greatly appreciate it if someone would explain it step by step.

 

*Quick Note*: I sculpted the high poly mesh on zbrush and transfered it back to blender along with the low poly mesh in order to create the normal map and ambient occlusion. For those who use zbrush to sculpt, is there a easier way of doing this on zbrush?

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The normal map and AO are applied to the mesh inworld. As is the texture. you have to save them as separate png or jpg files. Personally, I dont bother with a normal map unless it is very textured.

[Jake Koronikov]

Commenting the last normal map bake question:

You can bake normal map inside ZB. There is a nice tool called 'multimap exporter', located in plugin menu.

 

The idea is to use highest subdiv level and bake maps to lowest subdiv. Then you only need to take lowpoly model into Blender and use zb baked maps. My opinion is that xnormal is a better tool than zb when it comes to map baking...

[Drongle McMahon]

"The normal map and AO are applied to the mesh inworld."

The normal map(bumpiness) s applied inworld, but if you want to use baked AO, I think you have to combine it with the diffuse texture (brightness contrast adjust AO and multiply diffuse by AO) before uploading*. This is because, so far, there's only one diffuse texture per face in SL. If they ever allow compositing of multiple diffuse textures, which has been requested, this will mean we can use separate AO and potentially save a lot of texture data download (tiled small diffuse plus small AO).

*unless you know some way of using the specular map to mimic ao?

[Drake1 Nightfire]

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Drongle McMahon wrote:

"The normal map and AO are applied to the mesh inworld."

The normal map(bumpiness) s applied inworld, but if you want to use baked AO, I think you have to combine it with the diffuse texture (brightness contrast adjust AO and multiply diffuse by AO) before uploading*. This is because, so far, there's only one diffuse texture per face in SL. If they ever allow compositing of multiple diffuse textures, which has been requested, this will mean we can use separate AO and potentially save a lot of texture data download (tiled small diffuse plus small AO).

*unless you know some way of using the specular map to mimic ao?

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My bad, i thought they meant Spec maps.. AO are shodows.. i use that as the top layer on my texture when i make them..

[Dree Eames]

Just to clarify for anyone new to 3d Graphics, AO (ambient occlusion) is NOT shadow. Shadows are dependant on the lighting in the scene and are directional. An ambient occlusion map can be baked without any lights in the scene.

AO represents the areas on your mesh where the geometry is occluded (deep seams, cracks and/or spots and surfaces that are in close proximity to other meshes visible in the scene when baking). These are the areas where dirt, grime and tarnish would accumulate on real life objects.  RL surfaces tend to be  darker in these occluded areas as opposed to the parts that are subject to exposure to light which may fade and oxidize the exposed surfaces and the occluded spots tend to be hard to clean.   Incorporating an ao map into your texture adds realism and definition to your objects in a non-directional fashion (unlike shadows which follow the light source).

[Drake1 Nightfire]

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Dree Eames wrote:

Just to clarify for anyone new to 3d Graphics, AO (ambient occlusion) is NOT shadow. Shadows are dependant on the lighting in the scene and are directional. An ambient occlusion map can be baked

 without any lights in the scene.

AO represents the areas on your mesh where the geometry is occluded (deep seams, cracks and/or spots and surfaces that are in close proximity to other meshes visible in the scene when baking). These are the areas where dirt, grime and tarnish would accumulate on real life objects.  RL surfaces tend to be  darker in these occluded areas as opposed to the parts that are subject to exposure to light which may fade and oxidize the exposed surfaces and the occluded spots tend to be hard to clean.   Incorporating an ao map into your texture adds realism and definition to your objects in a non-directional fashion (unlike shadows which follow the light source).

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When talking about clothing in SL, AO is permanent shadows baked onto the texture. That is what i meant by shadows. They are talking about clothing, not a scene with buildings and cars and rubble.

[Dree Eames]

I do not wish to be argumentative here, Drake, however there are a lot of folks here just starting out and trying to learn the basics of 3d modeling. There's no distinction between AO used for clothing and AO used for buildings, rubble and bunny rabbits, it can be used for any of these things to fake out an impression of non-directional shading.  However, you wrote:  "AO are shodows."  You did not write " I use ao as a way to fake shadow effects"  or "people commonly use ao when making clothing in SL to create shadow effects."  

It can really confuse people who are come to the mesh forum trying to learn at a beginner level when the most basic terminology is not used correctly.

[Drongle McMahon]

"It can really confuse people who are come to the mesh forum trying to learn at a beginner level when the most basic terminology is not used correctly."

In that case, perhaps we should make it clear that ambient occlusion is essentially a means of calculating, at each point of a surface, the directly accessible surrounding unoccupied space, with distance-dependent falloff and threshold. The presence nearby of other surfaces, or other parts of the same surface, reduces the accessible space.

This can be used in simulating the effect of occlusion by nearby geometry on the intensity of "ambient" light falling on a surface, where "ambient" light means the sum of all indirect lighting sufficiently dispersed that it can be modelled by a completely non-directional source uniformly distibuted throughout space.This is what most people mean by an ambient occlusion map.

The ambient occlusion effect does not depend on accumulation of dirt or photobleaching of more exposed surfaces. However, since the distribution of these other effects is somewhat similarly distributed (although with different fallof and threshold), ambient occlusion maps can be used to simulate these effects too. When used in this way, the map might also be referred to as a dirt map or a crevice map.

[Pamela Galli]

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Drongle McMahon wrote:

 

This can be used in simulating the effect of

occlusion

by nearby geometry on the intensity of "

ambient

" light falling on a surface, where "ambient" light means the sum of all indirect lighting sufficiently dispersed that it can be modelled by a completely non-directional source uniformly distibuted throughout space.

 

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[Dree Eames]

With all due respect Drongle, we can offer folks  completely misleading  answers such as referring to ambient occlusion as "shadow",  or on the other hand we can bedazzle and overwhelm beginners who come here needing our assistance by spewing an over-abundance of eye-crossing technical jargon.  I think it's fair to compromise and give a definition that is somewhat simplified and "digestible".  

Clearly from your history as a technical adviser and expert on this forum -  something  is well appreciated by myself and other forum followers - it's been a long time since you were a beginner at this. For me it wasn't that long ago and I know what it means to get accurate definitions that are understandable and concisely stated.

[Drake1 Nightfire]

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Dree Eames wrote:

With all due respect Drongle, we can offer folks  completely misleading  answers such as referring to ambient occlusion as "shadow",  or on the other hand we can bedazzle and overwhelm beginners who come here needing our assistance by spewing an over-abundance of eye-crossing technical jargon.  I think it's fair to compromise and give a definition that is somewhat simplified and "digestible".  

Clearly from your history as a technical adviser and expert on this forum -  something  is well appreciated by myself and other forum followers - it's been a long time since you were a beginner at this. For me it wasn't that long ago and I know what it means to get accurate definitions that are understandable and concisely stated.

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When referring to making clothing textures for a mesh object is it not accurate to say that the Ambient Occlusion is commonly referred to as the Shadow layer? That is what each and every Mesh template creator tell you to use it for. "Make the white channel into an alpha and use it to bake the shadows." If you remove the white channel you are left with a perfectly mapped shadow layer... Which is why I called it shadows. The OP is asking about clothing, hence why I used termminology commonly used in creating clothing.

You keep saying it's used to generate shading... What is shading on clothing? SHADOWS! You want to talk about using beginner language, use it then. Every class i went to called the AO layer the shadow layer. Forgive me for using beginner language.

[Drake1 Nightfire]

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Dree Eames wrote:

I do not wish to be argumentative here, Drake, however there are a lot of folks here just starting out and trying to learn the basics of 3d modeling. There's no distinction between AO used for clothing and AO used for buildings, rubble and bunny rabbits, it can be used for any of these things to fake out an impression of non-directional shading.  However, you

 wrote:  "

AO are shodows."  You did not write " I use ao as a way to fake shadow effects"  or "people commonly use ao when making clothing in SL to create shadow effects."  

It can really confuse people who are come to the mesh forum trying to learn at a beginner level when the most basic terminology is not used correctly.

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"non-directional shading"...... Technical jargon for ... SHADOWS.

[Pamela Galli]

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Drake1 Nightfire wrote:

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"non-directional shading"...... Technical jargon for ... SHADOWS.

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Shadows are directional. That is not a very technical term, I dont think.

 

I am not aware of the terminology clothing template users use*, but shadows and AO are different things, and produced in different ways:  to bake shadows you must add lights with shadows enabled and choose Shadow or Full Render to bake.  To bake AO you dont need any lights and you choose Ambient Occlusion to bake.

It is not necessary to make either of them alpha, either -- you just use Multiply.

 

You can also see the difference in SL by turning on shadows and Ambient Occlusion and seeing the very different effects those settings create. YOu can have one or the other or both.

 

* When I have purchased sculpt kits in the past, some offered both shadow and AO maps. 

[Dree Eames]

The interesting thing here is it's not about either you or me.  It's about the beginners that come to the forums trying to learn a skill filled with complicated confusing terminology and methods.  And it's learning these skills that keeps many potential new members to SL  engaged and involved in Second LIfe.   

I have yet to take a class where the instructor hasn't pointed out that Ambient Occlusion is a trick to fake out what appears to be shadows followed by a further explanation of what the difference between AO and true shadows is.  You chose to omit this from your publically posted forum contribution, which is fine.  However from my perspective these posts are  viewed by folks interested in mesh creation whether they are making SL specific clothes or not.  And I chose to chime in and clarify a point here.  Also completely fine.

There's no need for you to get defensive or argumentative.  You are not technically wrong for omitting this explanation, nor was I wrong for chiming in with clarification of the term.  Please re-read my post and then re-read it again.  you will see that I posted to add an explanation specifically for beginners reading this post and I was not calling you out to provide as much assistance as possible to help others. 

I know from personal experience that beginners lurk for months on these creation forums struggling to absorb as much as they can until they stop feeling utterly confused and defeated and start feeling bold enough to contribute.  Posting is getting thin here on the Mesh forum and we can use new contributors.  Why not encourage others to participate and help them along  by recalling that what we post is intended for the wider audience who may  appreciate a more through explanation when someone takes the time to offer one. You aren't obligated of course to provide this, but don't step on the toes of someone who WILL take the time to contribute this added information.  And I will continue to chime in where I personally think it is helpful to provide clarity for novices to 3d mesh creation.

Please also know that Second Life mesh clothing designers are not the be-all-and-end-all to mesh creation and what they use for terminology is not a guideline for mesh creation in a general sense. This is not the clothing design forum -  and perhaps this aspect of the topic even belongs on the texture forum - however the techniques and terminology of mesh creation are the same regardless of what you choose to use it for, be it clothes, tractors, houses or terrain.  Someone who will never make a piece of clothing in SL will be reading your posts to get information in a general sense and may easily adopt the term and use it incorrectly, then become confused when they watch tutorials, etc..

[Coby Foden]

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Drake1 Nightfire wrote:

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Dree Eames wrote:

With all due respect Drongle, we can offer folks  completely misleading  answers such as referring to ambient occlusion as "shadow",  or on the other hand we can bedazzle and overwhelm beginners who come here needing our assistance by spewing an over-abundance of eye-crossing technical jargon.  I think it's fair to compromise and give a definition that is somewhat simplified and "digestible".

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When referring to making clothing textures for a mesh object is it not accurate to say that the Ambient Occlusion is commonly referred to as the Shadow layer? That is what each and every Mesh template creator tell you to use it for.

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Personally I think that for the benefit of beginners it is very important to refer to things with the correct terminology. Beginners can easily get confused if "some possibly commonly used - not actually correct terminology" is used to explain things.

Even ambient occlusion can be explained with easily understandable terms.

Like here, for example:

http://en.wikipedia.org/wiki/Ambient_occlusion 

"In computer graphics, ambient occlusion is a render technique used to calculate how exposed each point in a scene is to ambient lighting. The enclosed inside of a tube is typically more occluded (and hence darker) than the exposed outer surfaces, and the deeper inside the tube, the more occluded (and darker) it becomes."

Anybody can understand that explanation, no need to confuse things telling that they are used to create shadow effect on clothes. Because technically they are NOT shadows.

[Edit]

Well, in one other source I read this:

 

"Now let’s be clear what ambient occlusion really is.  It is the 'occlusion' or 'clouding' or 'blocking' of 'ambient' light.  Ambient light means indirect light; Light that does not come directly from a light source but first bounces off one or more surfaces before arriving at the subject.  So Ambient Occlusion simply means shadows from bounced light."

 

So, to comply I overlined the last sentence of my original post. :matte-motes-whistle: :matte-motes-bashful: :smileyvery-happy:

[Jake Koronikov]

It is a pleasure to follow sophisticated argumentation between sophisticated people in this thread

Some of my opinions about shadows and ambient occlution:

Direct light comes directly from light source.

Indirect light comes from same light but via bouncing from other surfaces. Surfaces do not need to be reflective, also matte lambertian surface emits light rays back

Global Illumination is a method for calculating scene lighting taking into account both direct lighting and indirect lighting.

Shadow is an area of darkness (not necessary black) created when a source of light is blocked - either direct or indirect.

Ambient occlution is a method for *simulating soft global illumination shadows* caused by white ambient light in the scene.


There is no AO in real life. AO is used in only in computer graphics to mimic real life situation where light rays bounce between surfaces with complex mathematics. This is also sometimes called global illumination calculation.

In real life you can think a long cylinder with open ends. Take it outside when it is overcast day. Overcast day is a good example of pure ambient light, the light rays come equally from all around. Look inside the cylinder and you will
see the middle parts of the cylinder darker than the parts more close to the ends.

Reason for darkening is not caused only by shadows, but also because light rays bouncing inside the cylinder are absorbed, bounced back outside, destroyed, turned into some weird quantum electron energies and so on. All the light rays will never reach the middle parts of the cylinder. The bouncing light rays inside the cylinder are sometimes called indirect lighting. Indirect term is used because light rays are not coming directly from the light source, but bouncing from another surface.

AO calculation does not compute these bounces and absorbed light rays. Instead, it tries to mimic same kind of a result without using raytracing calculation. AO calculation finds out how much there is geometry around each point, and gives the point a color between white and black. The result is simplified simulated global illumination effect.

An example where AO calculation goes totally wrong:
Take outside another cylinder, made of very bright and scratch-free steel. Look inside it - the bright areas are everywhere. You might even find brightest spots in the middle of the cylinder. The global illumincation calculation would solve this, but simplified AO calculation does not.

(Well, in principle multiplying AO over other texture maps are somewhat wrong method. AO should not be multiplied over specular highlights, glossy highlights, reflections and so on)

So to put it simple. AO map carries information from both shadows and global light rays, with very simplified assumptions about material properties.