3D-Visual Scooter – VESPA LX50 (Free interpretation ... · You can use most of the standard material types avain 3ds Max when renderilable ing with mental ray ®, and you can ﬁ

3D-Visual Scooter – VESPA LX50 (Free interpretation,reproduced by permission of PIAGGIO GROUP).

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Chapter 4 mental ray ® and materials

4.1 Introduction You can use most of the standard material types available in 3ds Max when rendering with mental ray ® , and you can fi nd a listing of unsupported materials in the Help fi les for 3ds Max. Specifi c mental ray materials are identifi ed in the Material/Map Browser by a blue sphere, whereas the mental ray maps are identifi ed by a yellow sphere. mental ray materials can be rendered only with the mental ray renderer.

A little historical background might be helpful in understanding mental ray materials. Earlier in the development of mental ray, you could use the mental ray material or a subsurface scattering (SSS) materials type. These mate-rials had many numeric value adjustments that were diffi cult to use and were not at all intuitive. You had to know a lot about the mathematics behind the development of these materials before any of the adjustments would make sense.

Arch & Design and Car Paint materials were developed to offer a more 3ds Max-like environment with termi-nology and adjustments similar to standard materials. In this chapter you ’ ll learn to take advantage of the power and fl exibility of these newer materials.

There will also be a discussion of the newest material type in mental ray called ProMaterials. These materials have an even simpler interface and require fewer adjustments, making them useful for very quick preliminary renderings, but limiting their usefulness in production by their simplicity and lack of control.

Arch & Design and Car Paint mental ray materials are designed to take advantage of the renderer to produce convincing materials which have qualities that closely simulate the physical world. For most 3ds Max uses, these will provide high levels of fl exibility and effi ciency, while having a relatively logical interface and terminology for controls and adjustments.

Among the most diffi cult material attributes to deal with in the Standard materials and scanline renderer are refl ections and refractions. In this chapter you ’ ll learn about several of the mental ray materials that you can use

Rendering with mental ray and 3ds Max

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in the majority of your production — Arch & Design, Car Paint, and ProMaterials — where the default parameters for refl ections and refractions keep you from getting into serious trouble.

You ’ ll also learn some tricks and tips on using Arch & Design and Car Paint materials that will increase your fl exibility in applying materials to objects. We will cover the following topics:

● Arch & Design material ● Car Paint material ● Multiple materials on single objects ● Multi/Sub-Object material ● Masking techniques ● Utility Bump Combiner

4.2 Arch & Design material Arch & Design mental ray material provides you with a balance of ease of use and fl exibility. There are templates that automatically adjust parameters for many of the commonly used real-world materials and provide you with an excellent starting point for making your scenes convincing. But Arch & Design materials also have many of the controls exposed that, when you become comfortable with editing materials, will allow you to fi ne-tune parameters to satisfy your clients ’ needs.

Arch & Design (and ProMaterials) materials are designed to be physically correct and energy conserving. It ’ s not that your heating bills will be any lower by using mental ray materials, but the energy conservation aspect means that the materials are designed to prohibit you from breaking the laws of physics by adjusting parameters. The sum of the energy from the diffuse component, refl ection, and refractions is always smaller than 1.0 so that neither of these components can overpower the others. For example, because transparency takes energy from the diffuse component, when you have total transparency, you can have no diffuse color. Refl ectivity takes energy from both the diffuse component and transparency, so a material that is completely refl ective can have no diffuse color or transparency. And translucency (a special form of transparency) will automatically alter the percentage of transparency versus translucency. Everything is kept in balance.

Note: One problem with this approach is that you can ’ t create fanciful materials when using Arch & Design materials. For that, you need to combine the individual mental ray materials and shaders, the description of which is beyond the scope of this book.

Let ’ s look at the Arch & Design material to familiarize ourselves with some of the important components and parameters. You ’ ll learn about the following topics:

● Arch & Design templates ● Controlling refl ections ● Self-illumination ● Cutout maps ● Ambient occlusion and round corners

Chapter 4: mental ray and materials

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Again, Arch & Design materials have templates for some of the common materials you will encounter in a typical production environment in which you are striving for “ realistic ” render-ings. Some of these templates simply change the basic parameters, whereas others have maps associated with them. For most of the exercises, you ’ ll use an outdoor scene that has a hot rod that already has basic materials applied to it.

4.2.1 Arch & Design templates Arch & Design templates are easy to access and provide you with a starting point for developing your own materials. We emphasize that these templates should be used as starting points and that you will eventually learn to adjust parameters to customize your own materials. It is not particularly professional to go into a presentation and have your materials look exactly like your competitor ’ s materials. You need to develop some sort of a signature “ look ” that distinguishes your work from everyone else ’ s.

4.2.1.1 Exercise: Setting Arch & Design templates 1. Open the fi le called Ch04_Arch_Design_01.max from the CD-ROM and save it to your hard drive with

the name Ch04_Arch_Design_02.max. Render the Camera01 viewport, and you ’ ll see a deep shiny red paint on the body of a hot rod (see Figure 4.1 ) Open the Material Editor and highlight the Body material in the top row, second from the left sample window.

2. In the Templates rollout at the top of the Arch & Design material, click on the (Select a template) drop-down list and choose Matte Finish (see Figure 4.2 ). Read the description of the changes in the material on the left side and render the Camera01 viewport again. The color of the hot rod body hasn ’ t changed, but the lack of refl ections has certainly altered the look of the material, and your client would be convinced that this is a matte fi nish (see Figure 4.3 ).

3. Choose the template called Glossy Plastic in the drop-down list and render the scene. Even though the diffuse color of this template is beige, the ren-dered image is a very glossy white because of the strong daylight and contrasting exposure control set-tings (see Figure 4.4 ). Again, these templates are simply starting points and must often be adjusted for your scene.

Figure 4.1 A red hot rod with green fenders in an outdoor daylight scene.

Figure 4.2 Change the template for the Arch & Design material.


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4. Choose the Leather template and render the scene (see Figure 4.5 ). This template adds a color map and a bump map along with changes to the refl ectivity and glossi-ness. In the Material Editor, choose another sample window and then return back to the Body material sample window. The name of the template that you last used is no longer shown in the drop-down list, making it diffi cult to determine what parameters this material now uses.

5. Close all windows and dialogs and save the fi le. Use the templates to get yourself started with materials but take the time to study them to see what changes have been made so that you can learn to make your own custom materials. Creating good materials will give you a strong competitive edge over your competition and help you make adjustments to adapt to particular lighting scenarios.

The Arch & Design templates are an aid to production but cannot be relied on to satisfy all conditions in a typical production workfl ow. Be prepared and be fl exible to create your own materials.

4.2.2 Controlling refl ections BRDF. Bidirectional refl ectance distribution function. One of mental ray ’ s biggest problems is the acronyms and terminology used to describe parameters; it is often confusing or even incomprehensible. Let ’ s try to make some sense of the concept to help us with our daily production. Actually, BRDF is nothing other than the fact that refl ection of objects in materials depends on the angle from which you are viewing the refl ections.

Refl ections are very important within materials to help the viewer determine the hardness of the surface of the material. Strong refl ections indicate a hard, smooth surface; whereas weak, blurry refl ections, or no refl ections, indicate a surface that is soft and porous. You ’ ve already seen how refl ectivity of materials can be controlled with the templates, but it ’ s often advisable to adjust the refl ections to suit your particular needs. Even though a material in real life is highly refl ective or very fl at, you may need to adjust the refl ectivity in your rendered scene to draw the viewer ’ s focus toward or away from objects. You need to be in control.

In the next exercise, you ’ ll look at the BRDF parameters of the Arch & Design material to gain an understand-ing of the control you have over refl ections. You will learn to control the amount of refl ectivity based on the angle from which the surface is viewed.

Figure 4.4 The Glossy Plastic template gives unexpected results under these lighting conditions.

Figure 4.3 The Matt Finish template disables all refl ectivity while leaving the original material color.


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3. In the BRDF rollout, choose the Custom Refl ectivity Function radio button. These parameters and corresponding graphs allow you to control the amount of refl ectivity on surfaces perpendicular or parallel to the surface and to adjust a curve to control the transition between the two. These default settings are the image you have stored in the RAM Player. Enter 1.0 in the 0 deg. refl . fi eld and 0.2 in the 90 deg. refl fi eld, thus reversing the values; then render the scene (see Figure 4.8 ). You can use the RAM Player to compare the images.

4.2.2.1 Exercise: BRDF control of refl ections 1. Open the fi le called Ch04_BRDF_01.max from

the CD-ROM and save it to your hard drive with the name Ch04_BRDF_02.max. This is the same scene you worked with at the beginning of the preceding exercise with glossy red and green paint on the hot rod. Render the Camera01 viewport and save the rendered image in Channel A of the RAM Player.

2. Open the Material Editor and highlight the Body material sample window; top row, second from the left. In the BRDF rollout, choose the By IOR (Fresnel refl ections) radio button (see Figure 4.6 ). This will cause refl ections to change based on the angle from which the surface is viewed. Render the scene (see Figure 4.7 ). Figure 4.5 Templates such as Leather add maps and change

parameters of the Arch & Design material.

Figure 4.6 Fresnel refl ections are primarily for glass, water, and metal.

Figure 4.7 The Fresnel refl ections are minimal except on the surface of the hood, which is at a steep angle to the viewer.

Note: Fresnel was a French mathematician who designed, among other things, the lighthouse lens. The concentric rings of a lighthouse lens focus the beam of light in a straight line to make it visible at greater distances. The effect here is to reduce refl ections on surfaces per-pendicular to the viewer while enhancing refl ections on surfaces that are nearly parallel to the viewing angle.


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4. Undo the two preceding steps (return the values to the defaults) and, in the BRDF rollout, enter 1.0 in the Curve shape fi eld. Render the scene (see Figure 4.9 ). The straighter the curve shape, the more even the transition between the greatest and least refl ectivity. If you load this image in Channel B of the RAM Player, you ’ ll see that the refl ections are similar, regardless of the angle from which they are viewed.

5. Close all windows and dialogs and save the fi le. By adjusting the refl ectivity of surfaces based on the angle from which they are viewed, you can control the viewer ’ s per-ception of the surfaces and materials. This has nothing to do with reality, but it is a subjective adjustment that gives you greater control over your rendered images.

You will need to practice adjusting BRDF parameters, and you will need to observe surfaces in the real world to have some basis for making a judgment that will still appear convincing to the viewers and that helps you control their perception of your scene.

Traditional oil painters, the Dutch Masters, for example, effectively used artifi cial refl ections to add a feeling of 3D space and make their materials more appealing and convincing to viewers.

4.2.3 Self-illumination Self-illumination is the ability of a material to seemingly glow from within. Arch & Design materials have built-in self-illumination functionality that also allows the material to cast light when rendered with fi nal gather indirect illumination.

Figure 4.8 Reversing the BRDF values reverses the strength of refl ectivity at the extreme angles.

Figure 4.9 A fl at Curve shape minimizes the transition between the greatest and least refl ections, regardless of the angle viewed.


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Next, we ’ ll do an exercise in which the hot rod is in very early morning light, and there is a plaque conveniently positioned right in front of the passenger side headlight. You will learn to activate the self-illumination for the headlight material and then enable it to cast light onto the sign.

4.2.3.1 Exercise: Self illuminating headlights 1. Open the fi le called Ch04_self_illum_01.max from the CD-ROM

and save it to your hard drive with the name Ch04_self_illum_02.max. Render the Camera01 viewport. You ’ ll see the sun is very low, the hot rod is barely visible, and the headlights are obviously turned off (see Figure 4.10 ).

2. Open the Material Editor and use the Material/Map Navigator to activate the Headlight material that is part of a Multi/Sub-Object material (see Figure 4.11 ). You ’ ll learn more about Multi/Sub-Object materials later in this chapter.

3. In the Self Illumination (Glow) rollout, check Self Illumination (Glow) (see Figure 4.12 ), and then render the Camera01 viewport. The glass of the headlights now appears to have a very dull white glow; they are now self-illuminating but not casting any light onto the sign.

4. In the Self Illumination rollout, increase the Phys-ical Units (cd/m 2 ) to 150000. This boosts the intensity of the self-illumination and will make the headlights appear brighter but still not cast any light. In the Global options area, check Illumi-nates the Scene (when using FG). Render the Camera01 viewport, and you will see that the headlights are now much brighter and casting

Figure 4.10 The hot rod just before dawn with the headlights off.

Figure 4.11 Activate the Headlight material in the Material Editor.

Figure 4.12 Self-illumination is a material attribute.


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light on the sign in front of them (see Figure 4.13 ). Remember that you must render with fi nal gather for the material to actually cast light.

5. Close all windows and dialogs and save the fi le. A self-illuminated material that casts light is not a substitute for a photometric light that you would use for real headlights, but is used to simulate the dull glow of a very diffuse light.

Self-illuminated Arch & Design materials can make your scenes more convincing when used on soft glowing light sources like TV screens or computer monitors, neon lighting, even glowing lights on the front of a com-puter panel. Enabling the material to cast a diffuse light adds an extra dimension to the effect without being a large drag on productivity.

4.2.4 Cutout maps Standard materials rendered with the scanline renderer in 3ds Max have always been able to use maps in the Opacity slot to create the illusion of transparency. White pixels in the map are opaque, black pixels are transpar-ent, and gray pixels are somewhere in between.

In mental ray, Arch & Design materials maps can still be used to create the illusion of transparency, but the maps are now placed in a slot called Cutout. The concept is similar where black pixels “ cut out ” the surface of the object, and gray to white pixels vary from semitransparent to opaque.

In the next exercise you will learn to use an existing map in the hot rod scene. You will create the bump maps on the side of the truck and around the doors to simulate a pipe-framed open vehicle instead of the solid body truck you ’ ve used in previous exercises.

4.2.4.1 Exercise: Cutout maps for transparency 1. Open the fi le called Ch04_cutout_01.max from the CD-ROM and save it to your hard drive with the

name Ch04_cutout_02.max. Render the Camera01 viewport to see the hot rod that has bump maps applied to the side to create raised areas (see Figure 4.14 ).

2. Open the Material Editor and make sure that Body material is highlighted; top row, second from left sample window. In the Special Purpose Maps rollout, you ’ ll see the map listed in the Bump slot that creates the

Figure 4.13 Brighten the intensity and enable the light-casting capability of the material.


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Cutout maps are an important component of Arch & Design materials that allow you to create simple geometric objects that appear much more complex in the rendered image. By simulating geometry with cutout maps, you can use low polygon models while increasing productivity.

4.2.5 Ambient Occlusion Ambient occlusion is a method of emulating the look of real-world lighting where bounced light, or global illumination, cannot fi nd its way into the cracks and crevices where objects make

raised areas. Drag and drop the map from the Bump slot onto the None button for Cutout (see Figure 4.15 ); then choose Instance in the Copy (Instance) Map dialog and click OK.

3. Render the Camera01 viewport (see Figure 4.16 ). Most of the red body of the hot rod has disappeared, but the portion remaining still has the raised areas. Both effects are created by the same white map on a black background, and the black pixels in the map have “ cut out ” most of the body.

4. Close all windows and dialogs and save the fi le. While making the body of the hot rod disappear may not be the most logical use of a cutout map, it certainly illustrates the process of applying cutout maps. The major difference between cutout maps and the previously used opacity maps is that cutout also makes the glossi-ness values disappear from the cutout areas.

Figure 4.14 White maps on a black background create the raised areas on the hot rod body.

Figure 4.15 Clone the bump map as an instance into the Cutout maps slot.

Figure 4.16 A grayscale map is used to cut out areas of the geometry.

Note: The bump and cutout maps used in these exercises were created using a method that you will learn later in Chapter 6 when creating a wake for a boat. You can see the 2D shapes used for generating the maps in the Camera01 viewport.


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contact with each other. This option is built into Arch & Design and some ProMaterials that you may have already experimented with, although you couldn ’ t really see much of a difference. It can be a subtle effect, but when adjusted properly, it adds depth and contrast to your rendered scene.

Throughout this book we mention that many scenes rendered with mental ray lack contrast because global illumination, by defi nition, tries to fi ll everything with light. Ambient occlusion darkens the area where one object occludes (or hides) another, thereby adding contrast back into the scene.

Let ’ s try an exercise in which all objects in a scene have a light gray Arch & Design material assigned so that you can enable ambient occlusion to see the effect.

4.2.5.1 Exercise: Ambient occlusion for contrast 1. Open the fi le called Ch04_amb_occl_01.max from the CD-ROM and save it to your hard drive with the

name Ch04_amb_occl_02.max. This scene shows a moderately complex building in Copenhagen that has a light gray Arch & Design material assigned to everything. Render the Camera01 viewport; then open RAM Player and open the rendered image in Channel A. The brightly lit scene is relatively fl at and without contrast.

2. Open the Material Editor and make sure that the Grey_base material sample window is highlighted (third row, fourth from left). In the Special Effects rollout, check Ambient Occlusion and render the Camera01 viewport again. Move this rendered image into Channel B of the RAM Player and then drag the mouse back and forth to compare the two images. You should be able to clearly see increased contrast in the trim detail and in the hedge.

3. In the Special Effects rollout, enter 0 ′ 8 ″ in the Max Distance fi eld. This is the radius of the area for which ambient occlusion will be calculated from where two objects meet. Render the scene and load the image in Channel B of the RAM Player again; then drag the cursor back and forth to compare the images. There is now a noticeable difference in contrast (see Figure 4.17 ).

Figure 4.17 Ambient occlusion adds contrast to the scene, darkening the areas where objects intersect.


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4. Close all windows and dialogs and save the fi le. Ambient occlusion is one of those elements of a rendered image that the casual viewer would have a diffi cult time identifying but they perceive immediately that something is missing. This relatively effi cient process adds the subtle contrast to make your scenes more convincing.

4.2.6 Round corners with Arch & Design materials Another useful function of Arch & Design materials is their ability to simulate rounded corners on geometry. This is again a productivity issue in which complex geometry is simulated by the material. It ’ s almost as if the geometry were fi lleted as a machinist would round the sharp edges of metal or a glazier would sand the edges of glass.

In the next exercise, you will see an automobile wheel that has a hub that has been extruded, leaving it with sharp edges that are not convinc-ing to the viewer. To fi llet the geometry at this point would be very diffi cult, and the results might not be as expected. You will learn to use the Round corners attribute of Arch & Design materials to remedy this situation.

4.2.6.1 Exercise: Arch & Design round corners 1. Open the fi le called Ch04_rnd_corner_01.

max from the CD-ROM and save it to your hard drive with the name Ch04_rnd_corner_02.max. Render the Camera01 viewport and notice the edges of the star-shaped hub are very sharp and unconvincing (see Figure 4.18 ).

2. Open the Material Editor and highlight the Wheel material sample window; top row, second from left. In the Special Effects rollout, check Round Corners and enter 1.0 in the Fillet Radius fi eld (see Figure 4.19 ). The fi llet radius requires some experimentation, depending on the size of the geometry and the viewing distance, primarily. Notice there is a note that this is a shading effect and doesn ’ t alter the geometry.

3. Render the Camera01 viewport (see Figure 4.20 ). The wheel now appears as though the edges have been rounded so that they catch the light without adding the overhead of extra geometry. By using the material attributes to simulate geometry, you increase productivity and possibly have more fl exibility when editing the objects.

Figure 4.18 Filleting the geometry edges of the wheel ’ s hub would create unnecessary geometry for this rendering.

Figure 4.19 Enable Round Corners in the Arch & Design material to simulate fi lleted edges.


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4. Close all windows and dialogs and save the fi le. Round edges can be used to soften sharp-edged geometry effi ciently. It ’ s an illusion much like the bump maps that simulate geometry during rendering.

In this exercise you used round corners in the Arch & Design materials as a way to effi ciently make your scene look better. While this approach is not always a substitute for real geometry, you should use it as much as possible to reduce the overhead of too much geometry.

4.3 Car Paint material Another mental ray material type that is interesting and useful is Car Paint. You might think that we had already created car paint using the Arch & Design material in the preceding exercise. The Car Paint material type is intended as a specialized “ fancy ” paint that has metal fl akes which catch the light differently when viewed from different angles. That may seem like a very specialized material that you would very seldom use, but it has attributes that can help draw the viewer ’ s attention to or away from objects in your scene.

A primary component of the Car Paint material, besides the fl akes, is two colors that are displayed based on the viewing angle to the surface. For example, faces on geometry that are perpendicular to the viewer might get a dark green color, whereas faces that are parallel to the viewer would get a lighter green. This effect could be used to make the objects stand out from a dark background, or the colors could be reversed to make the objects stand out against a light background.

4.3.1 Fancy paint for the hot rod In the following exercise we substitute the Arch & Design material that was previously assigned to the hot rod with Car Paint material that has the same base color. You ’ ll make some adjustments to the Car Paint material to learn some of the basic functionality of this versatile material.

4.3.1.1 Exercise: Experimenting with the Car Paint material 1. Open the fi le called Ch04_carpaint_01.max from the CD-ROM and save it to your hard drive with the

name Ch04_carpaint_02.max. Render the Camera01 viewport to see that the red and green Arch & Design materials are still applied to the hot rod (see Figure 4.21 ).

2. Open the Material Editor and highlight the Body_car_paint material sample window (third row, third from the left). Drag and drop it onto the car body in the Camera01 viewport. Drag the green car paint material to the right of it onto the hot rod fenders and render the scene (see Figure 4.22 ). These Car Paint materials have both the Base Color and the Light Facing Color swatch set to the same color as the previous Arch & Design material. However, you can already see a distinct difference in the look of the materials, especially at the top edge of the body (see Figure 4.23 ).

Figure 4.20 The simulated round edges catch the light without the need of creating new geometry.


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3. In the Diffuse Coloring rollout, click the Light Facing Color swatch and change it to a much lighter shade of red; then do the same for the Fenders_car_paint green material (see Figure 4.24 ). This is the color of faces parallel to the viewing direction, whereas the Base Color is the color on perpendicular faces of geometry.

4. Render the scene, and you ’ ll see a signifi cantly lighter color on the hood, roof, and tops of the fenders, while the sides of the truck remain the same (see Figure 4.25 ). You might also see a roughness where the paint transitions from dark to light caused by the fl akes in the paint.

5. In the Flakes rollout, enter 0.0 in the Flake Weight fi eld to effectively disable the fl akes in the paint (see Figure 4.26 ). Again, the fl akes are a special attribute to simulate “ metal-fl ake ” paint that is often found on custom cars. When you disable the fl akes, the Car Paint material becomes more universally useful to control how an object stands out or blends in with its background.

6. Experiment with variations on the paint. For example, try a completely different color such as blue or orange in the Light Facing Color swatch. Then close all windows and dialogs and save the fi le.

Once you get over the fact that Car Paint material is only for car paint, it becomes a more logical choice when you are trying to separate your geometry from the background elements of a scene in order to draw the viewer ’ s attention toward or away from the object without changing scene lighting or geometry. Use it to have more fl exibility in your workfl ow, but keep in mind that Car Paint material is not “ energy conserving ” like the Arch

Figure 4.21 The Arch & Design paint materials look convincing.

Figure 4.22 Drag and drop the Car Paint materials onto the hot rod.

Figure 4.23 The Car Paint material changes based on the viewing direction.


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& Design material. This means that it is possible to make adjustments that have nothing to do with the physical world and end up with materials that might not be what you would expect.

4.4 ProMaterials It ’ s worth mentioning ProMaterials in this chapter on materials because it has been promoted heavily by Autodesk. ProMaterials are based on Arch & Design materials with physically correct attributes, but they have a high number of presets that create a material for you, such as ceramic, hardwood, stone, or paint (see Figure 4.27 ). This makes it very easy to simply drag and drop these preconfi gured materials onto the object in the scene and have them look convincing.

Sounds ideal, doesn ’ t it? Well, it does make it easier for sales representatives to impress the user without knowing a lot about 3ds Max, and it can be useful when you need “ quick and dirty ” materials in a hurry.

The problem with ProMaterials is that when you go into a presentation, your scenes might look very similar to your competitors, and fail to impress your client. Many of the parameters of ProMaterials are hidden from the user and not accessible for you to change. They also can take noticeably longer to render than other types of materials.

ProMaterials are the materials on Autodesk Revit models imported via the FBX fi le type, so all objects will have ProMaterials assigned. Use them if you need them, but in the meantime, learn to create your own Arch & Design materials, along with other types, to allow fl exibility and effi ciency in your workfl ow.

4.5 Multiple materials on single objects While the process of applying multiple materials to single objects is not specifi cally a mental ray issue, it

Figure 4.25 The car paint is lighter on faces parallel to the viewing direction.

Figure 4.26 Disabling the fl akes in the paint makes the material more versatile.

Figure 4.24 Make the Light Facing Color a lighter version of the Base Color for both Car Paint materials.


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is important enough to cover two of the common techniques in this book to provide you with productive tools in your day-to-day work-fl ow. These techniques are especially useful for Revit users because, by default, Revit tends to apply one material per object.

First, let ’ s defi ne a potential problem. Say your client decides that a shower curtain in a bathroom scene should be red and blue horizontal stripes instead of the current solid red material. In 3ds Max, it is very ineffi cient to have a simple object like a shower curtain be made up of three or four different objects. Having multiple objects would add unnecessarily to the memory used, and the multiple objects would be diffi cult to manage if you had to move the shower curtain.

To solve the shower curtain problem, you will learn about Multi/Sub-Object material and Material ID numbers. The key is that each individual polygon or face in your model has a Material ID number assigned to it that corresponds to the sub materials in the Multi/Sub-Object material type. You ’ ll learn how to select sets of polygons to change the Material ID numbers so that you have two materials on a single shower curtain. It ’ s quick, effi cient, and fl exible.

In another example, polygons may not be arranged in the proper confi guration to allow Material IDs to be applied logically. Let ’ s say you ’ ve imported a model from Revit with a wall that has been assigned white paint, and you spend several days adjusting lighting and rendering parameters for a presentation to your client. During the presentation, the client asks to see the bathroom wall with two materials applied: white paint and a checker pattern, with the bottom of the window opening as the division line; the white paint above and the checker pattern below.

Normally, you would have to go back to the Revit fi le, split the wall into two objects at the bottom of the window opening, and then the link or import the objects into 3ds Max before applying the new material. But alas, the client decides that maybe the division would work better at the top of the window opening, or in the middle, or perhaps a band of checks in between two bands of white. You get the point: the client needs to see some options before making a fi nal decision, and it ’ s a waste of time to keep bouncing between Revit and 3ds Max until the determination is made.

4.5.1 Multi/Sub-Object material type Again, Multi/Sub-Object material is not specifi cally a mental ray material type, but it can contain Arch & Design materials as sub materials, for example. In the next exercise, you ’ ll learn how to edit a shower curtain that has been created in 3ds Max with a series of modifi ers, but the technique will work equally well on a shower curtain or any other object that came from Revit. The model itself is not so important in this exercise, except that it has polygons confi gured to match the banding the client wants to see in this example.

Basically, two things are necessary to apply different materials to different polygons of an object:

● Multi/Sub-Object material ● Material ID #

Figure 4.27 ProMaterials are preconfi gured to represent common materials in the architectural fi eld.


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4.5.1.1 Exercise: Material ID numbers 1. Open the fi le called Ch04_MSO_01.max

from the CD-ROM and save it to your hard drive with the name Ch04_MSO_02.max. This is the same bathroom scene you used in Chapter 2 with a few minor changes to the fl oor materials. If you render the Camera01 viewport, you will see that the shower curtain is all red (see Figure 4.28 ), and the client has requested a red- and blue-striped shower curtain. The antialias-ing has been set to low for faster rendering, and this setting causes some glossiness arti-facts. However, that ’ s not important for this exercise.

2. In the Camera01 viewport, select the shower curtain and click the Zoom Extends All Selected button to fi ll all viewports with the shower curtain. Right-click in the Left viewport to activate it, and you ’ ll notice that the shower curtain is segmented horizontally (see Figure 4.29 ). You ’ ll use the polygons defi ned by those horizontal segments to assign a blue plastic material to create alternating blue and red stripes.

3. As objects are created in 3ds Max, they are automatically assigned Material ID numbers. This shower curtain was created from a Line object that has been extruded and distorted, and all the polygons were assigned Material ID #1. You ’ ll need to change every other segment to Material ID #2 so that those polygons will receive the second sub material in a Multi/Sub-Object material that you will create later. You ’ ll use a Mesh Select modifi er to select the polygons of every other segment. In the Modifi er List of the Modifi ed panel,

The Material ID numbers need to correspond to the sub materials in the Multi/Sub-Object material. You can change Material ID numbers of faces or polygons directly in editable mesh or editable poly objects or by apply-ing Edit Mesh or Edit Poly modifi ers to objects. Or, as you ’ ll learn in these exercises, you can apply specifi c modifi ers; one simply selects the face or polygon (Mesh Select) and then passes that selection of the modifi ers stack to a modifi er effect changes the Material ID number of the selection (Material). Using a series of Mesh Select and Material modifi ers retains the original modifi ers of the shower curtain in this scene for greater fl exibility in editing, and it ’ s more effi cient than the Edit Mesh or Edit Poly modifi ers.

Figure 4.28 The client wants to change the red shower curtain to red and blue stripes.

Note: Any time you apply an Edit Mesh or Edit Poly modifi er to an object, it doubles the amount of memory footprint that object takes up, and this can lead to ineffi ciencies and slow production. The combination of Mesh Select and Material modifi ers performs only very specifi c operations and there-fore a much more effi cient option.


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Figure 4.29 The shower curtain has been modeled with segments that are appropriate for a striped material.

choose the Mesh Select modifi er at the top of the list. Expand the modifi er in the stack view and highlight Polygon sub object mode (see Figure 4.30 ).

4. In the Left viewport, select alternating bands of polygons. The sole purpose of the Mesh Select modifi er is to effi ciently select sub objects to pass up the stack view to the next modifi er. There is a Selected by Material ID area in the modifi er that allows you to select faces or polygons only by ID numbers that have been previously assigned, but you cannot change any Material ID numbers here (see Figure 4.31 ).

5. In the Modifi er List of the Modify panel, choose the Material modifi er. Here, you can change the Material ID number for the polygons that have been selected by the Mesh Select modifi er below it. In the Parameters rollout, enter 2 in the Material ID fi eld (see Figure 4.32 ). The selected polygons now have Material ID #2 assigned.

6. In the Modify panel, Modifi er List, choose the Mesh Select modifi er. While this step is not absolutely necessary, it does “ cap ” the open selection set of polygons and ensures that you clear the open selection set and return control to the complete object. The shower curtain now contains polygons with two Material ID numbers that will correspond to the two materials in a Multi/Sub-Object material that you will create. Save the fi le. It should already be called Ch04_MSO_02.max.

Figure 4.30 The Mesh Select modifi er simply allows you to select a sub object level.


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4.5.1.2 Exercise: Multi/Sub-Object material You may have noticed in the shaded viewport that nothing has yet changed in the red material on the shower curtain. The Arch & Design material that was applied to the shower curtain is still applied to all polygons regardless of the Material ID numbers assigned to them. You ’ ll now learn to create the Multi/Sub-Object material that contains the two sub materials, red and blue plastic.

1. Open the fi le called Ch04_MSO_02.max from the preceding exercise if it isn ’ t already open. Save it to your hard drive with the name Ch04_MSO_03.max. Open the Material Editor and choose the red sample sphere called Shower_curtain. Be sure to keep this material as a sub material in a Multi/Sub-Object material. Click the Material type button Arch & Design (m) below the icons and double-click Multi/Sub-Object in the Material browser list (see Figure 4.33 ). Make sure the Keep Old Material as Sub-material radio button is selected in the Replace Material dialog and click OK.

2. By default, there are 10 sub materials, so in the Multi/Sub-Object Basic Parameters rollout, click the Set Number button and enter 2 in the Number of Materials fi eld. Click OK. Drag and drop the material from the fi rst slot onto the material of the second slot and then choose the Copy radio button in the Instance (Copy) Material dialog (see Figure 4.34 ) and click OK. You now have two red materials. Click the color swatch to the right of the second material and, in the Color Selector, change it to a bright blue and click OK.

3. You can see in the Camera01 viewport that the new improved material has been assigned to those polygons where you assigned Material ID #2

Figure 4.31 The Mesh Select modifi er allows you to select at sub object level to pass that selection up the stack.

Figure 4.32 The Material ID modifi er changes the Material ID number of the selected faces or polygons.

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Figure 4.33 Change the current material to Multi/Sub-Object material and keep it as a sub material.

Figure 4.34 Change the second sub material to a blue version of the red plastic material that was previously assigned to the shower curtain.


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(see Figure 4.35 ). Activate and render the Camera01 viewport, and you ’ ll see the shower curtain has blue and red stripes with the same glossiness and refl ectivity values (see Figure 4.36 ).

4. Close all the windows and dialogs and save the fi le. It should already be called Ch04_MSO_03.max. While the steps you have performed are simple and the concept of assigning Material ID numbers that corre-spond to sub materials is easy enough, the implications of this process on your work-fl ow can be enormous. There is no logical technical limit to the number of sub mate-rials in a Multi/Sub-Object material, so it ’ s conceivable that your whole scene could be made up of one object, but in reality you can use this technique to provide high levels of fl exibility in assigning materials while maintaining the effi ciency of having fewer objects in your scene.

Figure 4.35 The two materials show in the sample window and in the shaded viewport.

Figure 4.36 The two sub materials of the Multi/Sub-Object material share all the same plastic attributes except for the diffuse color when rendered.


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Multi/Sub-Object materials are one of the common methods of assigning more than one material to a single object, but it is dependent on having faces or polygons in the correct confi guration. Sometimes the geometry layout has nothing to do with the material assignments, so you will learn another method of applying multiple materials to single objects using “ masking. ”

4.5.2 Masking techniques The concept of masking in 3ds Max materials makes use of the luminance values, or brightness, of pixels in a map or image. White pixels allow the underlying effect to show, black pixels block the effect, and gray pixels partially block the effect. For example, if you mask a refl ection map with a black-to-white gradient ramp, you get for refl ection in the white areas, no refl ection in the black areas, and diminishing refl ections based on the brightness of the gray areas.

You ’ ll learn to use masking to satisfy the client ’ s wishes to have two separate materials on a wall, a white paint material and a checker pattern material. The confi guration of the faces in the wall geometry make it impractical to use the Multi/Sub-Object material and Material IDs. Like many clients, this one hasn ’ t completely made up his mind on exactly what confi guration he wants the materials to be, so it ’ s important that you work as fl exibly as possible to be able to adapt to future changes.

The solution in this case will be a Blend material that has a built-in mask slot. Much like the Multi/Sub-Object material, Blend is a standard material type that can contain two Arch & Design materials as sub materials with the option of a mask to reveal one or the other of the materials. You ’ ll use the existing white paint material and then add a checker pattern material with a Gradient Ramp map as the mask. The checker pattern and the gradient ramp mask must have separate mapping coordinates to fi t correctly, so you ’ ll learn about Map Channels, too. The important components of this process are

● Blend material type ● Mask map ● Map Channels

You ’ ll use the wall on the left side of the bathroom scene that has the window opening. The client would like the checker material below the window and the white paint material from the bottom of the window up.

4.5.2.1 Exercise: The Blend material A Blend material acts as a container for two other materials that can either be blended together with a mixing amount, or a mask map can be added to reveal one material or the other based on the luminance values of the map pixels.

1. Open the fi le called Ch04_masking_01.max from the CD-ROM and save it to your hard drive with the name Ch04_masking_02.max. In the Camera01 viewport, select the wall on the left called Wall_left . Press Alt-Q to isolate the selection. This makes it more effi cient to work on just this particular wall. Click the Zoom Extends All button to fi ll all viewports with the wall.

2. Open the Material Editor and activate the Paint_white material at the far right of the top row of sample windows. This is the Arch & Design material that has already been applied to the wall and will continue to be used on part of the wall. Click on the Arch & Design (mi) button below right of the sample windows


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Figure 4.37 Change the Arch & Design material for a Blend material, but keep the Arch & Design material as a sub material. This is the Paint_white material.

Figure 4.38 The Blend material has two copies of Paint_white, as you can see in the Mate-rial/Map Navigator.

and double-click Blend in the material browser (see Figure 4.37 ). Make sure the Keep Old Material as Sub-material radio button is selected and then click OK in the Replace Material dialog.

3. In the Basic Parameters rollout, drag the material from the Material 1 slot to the Material 2 slot. Then choose the Copy radio button in the Instance (Copy) material dialog and click OK. You now have two identical white paint materials as sub materials in the Blend material. Click the Material/Map Navigator button to open the navigator (see Figure 4.38 ).


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4. In the Material/Map Navigator, highlight Mate-rial 2. In the Material Editor, rename this material to Paint_checker. In the Main Materials Param-eters rollout, click the map shortcut button to the right of Diffuse Color and double-click on Checker map from the browser. This material now has the black-and-white checker pattern defi ning its color, as you can see in the Material/Map Navigator (see Figure 4.39 ).

5. Close all windows and dialogs and click the Exit Isolation Mode button to return the other objects in the scene. Save the fi le. It should already be called Ch04_masking_02.max.

Now you have two complete Arch & Design materials inside a Blend material. If you were to render the scene, you would see only Material 1: on the wall at the left of the scene, just like before you created the Blend mate-rial. The Blend material has a Mix Amount numeric value that would allow you to blend the two materials together; i.e., you would see a muddy mix of half white paint and half checker pattern bleeding through. This is certainly not what you want to show the client in this case, so the option is to use the Mask slot to apply a map with luminance values that allow one or the other, or a mix of the materials to show.

4.5.2.2 Exercise: Adding a Mask map to the Blend material 1. Open the fi le called Ch04_masking_02.max and save it to your hard drive with the name Ch04_masking_03.

max. Open the Material Editor and make sure the Paint_white sample window is active. Then click the Material/Map Navigator button to open it. In the Material Editor, rename the blend material Wall_checker. This material has been applied to all the walls and the ceiling of the bathroom; however, you want it only on Wall_left. In the Blend Basic Parameters rollout, drag the Paint_white material in the Material 1: slot onto the ceiling and the other three walls in the scene.

2. In the Blend Basic Parameters rollout, click the None button for the Mask slot and double-click the gradi-ent ramp in the Material/Map Browser (see Figure 4.40 ). Render the Camera01 viewport, and you will notice that the wall to the left has a large, faded checker pattern. Select the Wall_left object and, in the modifi ed panel, add a UVW Map modifi er. In the Parameters rollout, enter 1 ′ 0 ″ in the Length and Width fi elds to reduce the size of the checks to 6 ″ × 6 ″ each.

Figure 4.39 Change Material 2 to have the default Checker map as its diffuse Color and name it Paint_checker.

Tip: You can speed up test rendering in the Rendered Frame Window by setting the fi nal gather preci-sion slider to Disabled at the far left or by selecting the Wall_left object and changing the Area to Render to Selected. You will still be able to see the effects of the maps.

3. The Gradient Ramp map is a grayscale gradient pattern with black on the left and white on the right, which causes the blending effect to occur within a repeating 1 ′ × 1 ′ area because the gradient ramp uses the same UVW Map modifi er as the Checker map. The Gradient Ramp map needs to have its own UVW coordinates using Map Channel #2 that matches Channel #2 in the UVW Map modifi er (see Figure 4.41 ).

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Figure 4.41 Each map in a material can have its own mapping coordi-nates by matching the Map Channel numbers of the map and a UVW Map modifi er.

Figure 4.40 Assign the Gradient Ramp map to the Blend material ’ s Mask slot.


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4. The mask needs to be in a vertical orientation with a hard separation between black and white. Use the Material/Map Navigator to open the Mask: Gradient Ramp map. In the Coordinates rollout, enter 90 in the W.: numeric fi eld to rotate the map 90 ° . In the Gradient Ramp Parameters rollout, change the Interpolation drop-down list to Solid. Render the Camera01 viewport (see Figure 4.42 ). The Gradient Ramp is now half black and half gray. Right-click on the middle fl ag in the gradient ramp and click Edit Properties; then change the color to pure white (see Figure 4.43 ). Remember that black shows one of the blend materials, white shows the other, and gray shows a mix of the two.

5. Turn on Show Map in Viewport in the Gradient Ramp map. You would expect the Gradient Ramp map to show in the shaded Camera01 viewport, but it doesn ’ t. Navigate to the top level of the Blend material and choose the Interactive radio button to the right of the mask slot. Now the gradient ramp shows in the viewport to make the height adjustment easier (see Figure 4.44 ).

Figure 4.42 Rotate the Gradient Ramp map 90 ° and change it to solid interpolation for a sharp horizontal division.

Figure 4.43 The Gradient Ramp map must be pure black and pure white.

Figure 4.44 To see the mask map of a Blend material, turn on the Interactive radio button.


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6. You now need to adjust the position of the gradient ramp at the bottom of the window opening. In the Material Editor, navigate to the Gradient Ramp map level and drag the middle fl ag right until the map division is at the bottom of the window opening. Render the Camera01 viewport, and you will see that the position of the fl ag determines the break between materials (see Figure 4.45 ).

Figure 4.45 The position of the white fl ag adjusts the division point of the materials.

7. Click somewhere in the black area of the gradient ramp to create a new black fl ag. Then change the leftmost fl ag to pure white to give a white-black-white gradient ramp and adjust the position of the new fl ag to the top of the window opening in the Camera01 viewport. This reveals the checker pattern above and below the window opening when rendered (see Figure 4.46 ).

8. Close all windows and dialogs and save the fi le. It should already be called Ch04_masking_03.max. While the pattern may not be exactly the way you want it and will require further adjustment, you should clearly understand the concept behind the use of the Blend material with its masking option. This technique allows you to apply multiple materials to single objects with a high degree of fl exibility by using any grayscale mask that is appropriate for your situation.

Whether you use Multi/Sub-Object materials or Blend materials with a mask depends on several factors, includ-ing the underlying geometry, your ability to create maps, or just your personal preferences, but either technique is a way of increasing your fl exibility and your effi ciency in production. Either method can also benefi t from your knowledge of Map Channels. You can use up to 99 map channels in maps that correspond to the map channels in UVW Map modifi ers, so each map can be correctly sized independently of the others.

The limit to the number of materials that can be applied to a single object is limited primarily by your imagina-tion. Practice with a few simple scenes like this until you have a good feel for the concepts and the process.


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Figure 4.46 Masking provides high levels of fl exibility that can increase your productivity signifi cantly.

4.5.3 Utility Bump Combiner The way bump maps are evaluated in the Arch & Design material is different from the way they ’ re evaluated in the scanline renderer, and that severely limits the fl exibility of bump mapping. This bathroom scene has a tile fl oor that uses the Tiles map for color and as a bump map to make the tiles appear to be raised above the grout. The tile fl oor material is slightly glossy and refl ective, and as you ’ ll notice in the roughly rendered image, the grout is just as glossy as the tiles (see Figure 4.47 ).

First, you will learn to use masking at the map level to mask out the refl ections and glossiness in the grout for a more convincing appearance. Previously, you learned to mask at the material level, but in this particular case, you do not need two materials but only need to control the components within the material.

The client has decided that these large fl oor tiles should have a rougher texture, much like Mexican or Spanish tiles. You can easily create this effect with the scanline renderer and standard materials by using the Tiles map

Figure 4.47 The tile fl oor shows the same glossiness in the grout and the tiles.


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to bump the tiles up and then using a Noise map within the tiles area. This would cause secondary distortion in the tiles but not in the grout.

mental ray Arch & Design material does not allow bump maps to be evalu-ated within bump maps (this is also true for displacement maps) for a com-bined effect. However, there is a material type called the Utility Bump Combiner that will allow bump maps to be stacked in the material. You will need to use masking, though, to block the secondary bumps in the grout area.

4.5.3.1 Exercise: Masking glossiness and refl ections at the map level 1. Open the fi le called Ch04_combiner_01max from the CD-ROM and

save it to your hard drive with the name Ch04_combiner_02.max. Open the Material Editor and activate the material called Tile_terracotta (third from the left in the second row). Open the Material/Map Navi-gator. The material has a Tiles map in the Diffuse Color slot, another Tiles map in the Bump slot, and adjustments have been made to the Refl ectivity and Glossiness (see Figure 4.48 ).

2. In the Main Material Parameters rollout, click the map shortcut button to the right of Glossiness and double-click Mask in the Material/Map Browser (see Figure 4.49 ). This places in the Glossiness slot a Mask map that contains two map slots: Map and Mask.

3. White pixels in a mask cause the underlying effect to show, while black pixels in the mask hide the underlying effect — in this case the glossiness of the tiles. The material already has an appropriate map: the black-and-white Tiles bump map. Open the Material/Map Navigator and click and drag the bump map from the Navigator to the Mask None button. Choose the Copy radio button in the Instance (Copy) Map dialog and click OK (see Figure 4.50 ).

Figure 4.48 The fl oor material is a color map and a bump map.

Tip: You need to drag the bump map from the navigator rather quickly because when you click on it and hesitate, you are taken to the bump map level.

4. Render the Camera01 viewport, and you will see that the fl oor tiles are very refl ective and very glossy, but that the grout between the tiles is dull (ignore the bright artifacts from the glossiness precision settings; see Figure 4.51 ). The pure white color in the map now controls the amount of refl ectivity and glossiness rather than the numeric values in the Material Editor.

5. To dull the refl ections and glossiness, you can navigate to the Tiles map in the Mask slot and change the Texture color swatch of Tiles Setup area in the Advanced Controls rollout to a middle gray (see Figure 4.52 ).


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Figure 4.49 You need to mask the glossiness for the fl oor material.

Figure 4.50 Clone the bump map by dragging and dropping from the Navigator to the Mask ’ s Mask slot.


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Figure 4.51 The luminance value or brightness of the pixels in the map now controls the glossiness and refl ectivity.

Figure 4.52 The brightness values of the color swatch in the tiles mask map now controls the glossiness and refl ectivity of the tiles only.


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6. Close all windows and dialogs and save the fi le. It should already be called Ch04_combiner_02.max. In preparation for adding extra bump maps to the fl oor tiles, you have used masking techniques at the map level for a more convincing distribution of glossiness and refl ectivity.

The client has decided that he would like a textured Spanish-like style in which each tile has a slightly bumpy surface. 3ds Max 2010 and 3ds Max Design 2010 have a new material type called the Utility Bump Combiner that contains the base material and then provides multiple bump slots so that you can “ stack ” bump maps. However, as you ’ ll see, the bump maps are applied to everything in the material — tiles and grout. You want only the tiles to have the added bump map and will have to apply a Mask map to reveal the extra bumps only in the tiles area.

4.5.3.2 Exercise: Combining bump maps in Arch & Design material 1. Open the fi le called Ch04_combiner_02.max if it isn ’ t still open

from the preceding exercise. Save it to your hard drive with the name Ch04_combiner_03.max. Open the Material Editor and make sure the Title_terracotta sample window is highlighted and that you are at the top level of the material. You need to change this Arch & Design material type to the Utility Bump Combiner material type while keeping this as a sub material.

2. Click the Arch & Design (mi) button to open the Material/Map Browser and double-click Utility Bump Combiner (adsk). Make sure that the Keep Old Material as Sub-material radio button is selected in the Replace Material dialog and click OK. The Utility Bump Combiner contains slots for three bump maps with the original Arch & Design material providing the shading (see Figure 4.53 ). The original tiles bump map is still active, causing the tiles to appear raised above the grout.

3. In the Utility Bump Combiner (adsk) Parameters rollout, click the None button to the right of Bump 1 and double-click the Noise map in the Material/Map Browser. In the Noise Param-eters rollout, enter 2.0 in the Size fi eld. Double-click the Material sample window. Then resize it so that you can see that there are now two bump maps acting on the sample sphere, but the tiles in the grout areas are both affected by Noise (see Figure 4.54 ).

4. Click the Noise button at the Bump 1 level and double-click Mask in the Browser. Keep the old map as a sub map and click OK. Open the Material/Map Navigator and drag the bump map: Map #1 (Tiles) to the Mask slot (see Figure 4.55 ) as an Instance clone.

5. Navigate to the top of the material and enter 0.5 in the Multiplier fi eld of Bump 1 to reduce the amount of bump in the material (see Figure 4.56 ). The new Noise bumps are now masked from appearing in the grout areas. Render the Camera01 viewport to see the results.

Figure 4.53 The Utility Bump Combiner material contains the original fl oor material and provides three slots to stack bump maps.

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Figure 4.55 The Tiles map will mask the effect of the Noise map from the grout areas.

Figure 4.56 The relative amount of each bump map can be controlled with its Multiplier value.

Figure 4.54 The Utility Bump Combiner adds a Noise map to the current Tiles map.


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6. Close all windows and dialogs and save the fi le. It should already be named Ch04_combiner_03.max. The Utility Bump Combiner allows you to stack bump maps in mental ray Arch & Design materials, and masking techniques control where they affect the materials.

Utility Bump Combiner material can be used in conjunction with masking for increased fl exibility in creating materials.

Materials can make or break your presentations. You should use the power of the Arch & Design materials for mental ray in 3ds Max to create your own signature style that helps you stand out from the competition.

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