Facial Skin Layered Mapping

 

Part 3.5 – Mapping The Face: Layered Maps Overview

 

Before You Begin

It might be a very good idea to review the A:M 8.5 manual’s section on maps – specifically the sections on color, bump, specular intensity, specular size and diffuse maps.

Introduction

This section gives an overview of the process before you actually begin.  It covers:

The Maps

Maps are just images, usually targa or tga images (at least that’s what I favor) that are applied to the patches of the mesh as decals to control the various aspects of how the computer generated light will react to the patch surface.  In other words how it will look.   ‘Layered Mapping’ just means that you are stacking more then one image on top of another to further control different (or the same) aspects of how light reacts to the surface.  For the purposes of this discussion the terms ‘maps’ and ‘images’ mean the same thing: an image you’ve prepared to affect the way the surface reacts to light.

 

To apply a map you just select portion of the mesh, name the group something descriptive (just so you can get back to it), hide the rest of the model and, so the map will not become distorted, flatten mesh in an Action window (which we’ve just done in the previous steps).  Then, with the Action window active, you right click on the model, select new decal and specify the image you wish to use.   The image appears over the mesh in the Action window so you can position it.  The image is semi-transparent so you can see the mesh under it and there are translation handles along the edges that you can use to re-size the image.  Holding down the shift key while you drag on these handles forces the image’s aspect ratio to remain the same (this is normally what you want to do).  You can grab the image and move it around, right click on the image for a context menu with more options to help you position it (like flip horizontal or vertical) and also, you can use the properties in the PWS or Properties pallet to scale and move the image.  Once you’ve scaled and positioned the image you right click on it and select ‘Apply’ to ‘stamp’ it on the mesh.  Then you right click and select ‘Stop Positioning’ (or just click outside the image) to end the process.  The image is now applied to the mesh and can be viewed in shaded mode in the Action window (where the mesh is flattened) or in the modeling window to see the results.  If you messed up and wish to redo it, just open the Decal in the PWS expand the Stamp section, select the stamp within and press delete and repeat the process.  If you do not first delete the stamp, you’ll wind up with 2 stamps and the image will be stamped on the mesh twice.

 

Once the map is applied, you can then specify the attributes for the map such as what type of map it is (color, bump, etc.), the percentage that the map will be applied as well as other aspects.

 

A ‘Decal’ can have multiple images and multiple stamps.  Also the Decal has attributes that affects all of the maps and stamps that it contains. For the most part these can be ignored for the purposes of this tutorial, however, for fine tuning, tweaking the scale and postion here can come in handy.  One Decal attribute to note is the application method.  I will not go into explaining these here – they are fairly straight forward – except to mention that the default is ‘Planar’ and this is what we’ll be using.

 

Usually you apply the color map image first however, to assist in positioning at times you may want to apply a ‘guide’ image first.  This is later replaced by the map you really want to use by expanding the Image section of the Decal, expanding the image and specifying a new image to use.

 

Once a map is applied, a ‘stamp’ is created.  You do not need to ‘position’ the rest of the maps -- you will just reuse the same stamp.  This automatically aligns all of the maps and is a real time saver.   Figure 3.5.1 shows the Decal section in the PWS, the Decal attributes, the Image section, the images and their attributes and finally, the Stamp section and the stamp.

 

 

Figure 3.5.1

 

Map Types

The types of maps we’ll use for the skin will be Color, Bump, Specular Intensity, Specular Size and diffuse and are briefly described below.

 

Color

This holds all of the color information and only the color information.  That said, a wrinkle in the skin will primarily be done in the Bump map however, because the skin is compressed the color does in fact change – it becomes darker.  There for the bump map is normally used as part of the makeup of the Color map.   Other things to note about color maps are:

 

Fiigure 3.5.2 shows the final color map for the front section of the head for the Larman model (shown at the beginning of this section).  All these maps were 1277x879 pixels in size.

 

 

Fiigure 3.5.2

 

Bump

This is one of the most valuable maps for increasing realism.  It affects the reflection of light which makes it appear that the surface has ‘bumps’ in it or areas that are higher or lower.   The map should be gray scale: darker equals a depression in the surface; lighter equals a bulge in the surface.  However, be aware that it is the difference between one pixel and the next that determines depression/bulge.  This means that a gradual change between light and dark won’t show up much if at all.  Often several bump maps are used in a single decal; there might be one for ‘softness’, one for ‘pores’, one for ‘wrinkles’ and another for ‘whiskers’.   Also be aware that bump maps can cancel out each other if applied in the wrong order: generally their application is from smaller to larger (e.g. pores are smaller then wrinkles so they are applied before wrinkles).   Finally, an image that is the combination of most, if not all, of the bump maps is used to supplement the color map and, used as the base for the specular and diffuse maps.  Figures 3.5.3 through 3.5.5 show the bump maps used.

 

 

Figure 3.5.3 – Wrinkle map.

 

 

Figure 3.5.4a – Pore Map.

 

 

Figure 3.5.4b – Full size view of pore map

 

 

Figure 3.5.5 – Whisker Map.

 

Specular Intensity and Specular size

These are very important maps.  They determine the intensity and size of the of reflected light.  Hard surfaces that are oily or wet will have high intensity and  smaller size.  Soft surfaces that are oily or wet will have high intensity larger size.  These attributes can make a surface look like rock, plastic velvet, skin, etc. and also look dull, shiny, polished, dry, wet or oily.   These maps can also make a character look clam, nervous, scared, etc.   For faces you’ll follow some standard guide lines but then experiment to get the right look.  The areas on each side of the nose, just above the chin and above and in front of the ears are normally oily.  More oil is also present in wrinkles and the depression of each pore (and using the bump map as a base take care of this).  Under the eyes is soft while the forehead, nose and chin are harder.  Figure 3.5.6 and 3.5.7 shows the specular intensity and size maps used for Larman.

 

 

Figure 3.5.6

 

 

Figure 3.5.7

 

diffuse

The diffuse map adds the final touch needed for realism to any layered map set.  In the real world when you see a red object it really means that the object is reflecting the color red back to your eye (so it could be said that the object is really all colors but red LOL) but, not all of this reflected light makes it back to the viewers eye.  In a 3D rendering objects reflect all the light right back to the viewer’s eye – nothing is absorbed or scattered.  The diffuse map’s primary purpose is to simulate this element of the real world.   Over all, skin returns about 90% of the light to the viewer’s eye.  However, wrinkles, blemishes and the depression of each pore absorb and scatter a bit more so return a bit less (so again we use the bump map as the base for this).  The diffuse map is the last map that the light travels through before it reaches the viewers eye (or the camera).  Figure 3.5.8 shows Larman’s diffuse map.

 

 

Figure 3.5.8

 

Overview of Map Creation

Figure 3.5.9 shows a simplified flow of how the layered maps will be created.  As we’ll be covering this in detail I just want to provide a very simple overview right now.

 

 

Figure 3.5.9

 

As shown, you can start off with a high resolution picture of the front and side of the face and/or you can use reference material and build from scratch.  In both cases you wind up with the bump ‘Wrinkle Base’ and the ‘Color Base’.  From here the Wrinkle Base has enhancement layers added to it and then the other bump maps are created.  Most if not all of these layers are then combined in a certain ways to produce a) a color variation overlay for the Color Base and b) Bases for the specular maps and the diffuse map.  Finally, additional enhancement layers are added to most if not all of these.

 

Building Maps in Photoshop

Since all the maps for the same section share common elements, all of the maps are created in a single Photoshop document.  You have already prepared this document and this will make life far easier

 

The most important thing I can tell you is to take your time, focus, save versions and stay organized.

 

The second most important thing is this: If you combine two or more layers or adjust a layer without copying it first or, make adjustments without recording what you did, you will almost always come to regret it!  Unless you’ve saved to a new version, doing anything that forever looses individual parts of your work reduces your control and, sooner or later, is likely to result in the duplication of effort.  It is likely that you (like myself) will not come to fully believe this until you’ve done this for a while.  Developing facial maps is a very interative process: you will iterate over the maps moving forward, then deciding it needs this or that and then backing up, redoing and moving forward again.   You must lean to preserve each step you take and be sure that each step you take can be duplicated.

 

I very good practice I ignored during the initial creation of the Larman maps is recording what adjustments you make to a layer in the layer’s name.  I got the perfect specular and diffuse bases for ‘Section One’ (the front of the face) by slaving over the brightness and contrast settings for 2 days then, 2 weeks later when I started on Sections Two, Three and Four, I had no idea what settings I’d used for these maps!  This meant that not only could I not get the same awesome results for these other sections, I could not get the maps to match up perfectly and the seams could be seen!!  With a sickening feeling in my chest I eventually had to toss out those original perfect maps and start over again so that all the sections had the same settings and look.  I never felt that I got the maps quite as good as that original effort.

 

Figure 3.5.10 shows the layer pallet for the work file in which all the Larman maps were created.  Larman had older skin and was far more complex the most characters.

 

 

Figure 3.5.10

 

Mainly notice how may layers you can wind up with, how I locked the layers and layer sets when I was happy with them so I didn’t accidentally change them and also, how each layer has a descriptive name.  Its easy to create a new layer and leave the name “Layer 19” (as I did in the above example!) but it’s a bummer to have to run down 12 layers hiding each until you find the layer that you need.  Also notice how I did not record what adjustments I make in the layer names which led to a loss of work, a lot of time and in my case, quality.  We’ll get into how to avoid these mistakes as we progress forward.  Finally notice the ‘Notes’ layer… this layer holds the purple outline on the bump map you see on the right which served as a guide for changes I needed to make.  This is a great way to help yourself along – just remember to hide the layer before you output the maps.

 

The Order of Layered Maps (in the PWS)

There is a proper order for placing the maps on the character.  Figure 3.5.11 shows a logical view of this order but be aware that in the A:M PWS this is reversed with the diffuse map being the lowest image in the decal set.

 

 

 

Figure 3.5.11

 

The color map sits at the bottom and is applied first.  Next come the bump maps placed largest details to smallest so that the gray scale image do not cancel each out.  Laying on top of the color and the texture (bump maps) are the specular maps  Finally, affecting all the maps comes the diffuse map.

 

What’s Next

The in the next sections you will begin building the Color and Bump Wrinkle maps.  As mentioned there are two paths you can take.  If you have an older subject, using an image is usually best if you have one.  For younger faces, baking from scratch is usually best as an image may place more then you want into the base maps.

 

You might want to look over each method before you decide.  To be honest, using front and side images as I did for the Larman model has more steps to it but I would have been hard pressed to get all the details this method provided.

 

If you have a high quality, high resolution (640x480 or larger is best) of both the front and side…

Go to Part 3.6a – Mapping The Face: Creating the Base from an Image .

 

If not, or you just would rather build the Color Base and Wrinkle Base from scratch…

Go to Part 3.6b – Mapping The Face: Creating a Base from scratch .