4
ON THE WEB The tutorial files are in the Stop Press section of www.3dworldmag.com ften it’s the small details like scratches, scuff marks and dents that lend a certain realism to even the most fantastic objects. In fact, the everyday wear and tear that can only be re-created with a careful mix of hand-painted textures and photographic reference can be the thing that really makes or breaks a model. In this tutorial, we’re going to take an otherwise pristine droid and give it a good visual thrashing. Imagine it is battle-scarred from years of conflict and abuse: we need to create the tell-tale signs of everyday life. Its edges are faded and worn, scratches in exposed areas have been filled with ground in dirt, and recessed areas have become clogged up and decals have decayed over time. It is often these touches that can make your model shine, adding character to an otherwise lifeless object. And knowing where the scratches, grazes and grime will be most effective can be an artform in itself. Using scene files available on the 3D World website, we will begin by using the Render to Texture dialog to render an Ambient Occlusion (MR) map. This is used throughout the texturing process, both as an aid in knowing where to paint (and where not to) and as a mask for filling new layers. This map can be multiplied above the texture, offering free ambient occlusion without any extra render overhead. It’s a technique commonly used in game texturing, where real-time ambient occlusion would be too expensive to use otherwise. We will also look into using a scratch brush to roughen up the edges of the model. While the brush itself is important, painting these scratches should be done in a very loose fashion, as if you were roughly scribbling on paper. We will create a base texture, followed by colour fills that use the Use All Layers function in Photoshop, an often overlooked feature that can quickly and effectively add much-needed variation to a texture. Finally, we’ll create a greyscale bump and reflection/specular map using a modified version of the colour texture. Layers and the blending options in Photoshop will help us create a hard-surface texture that looks like it’s seen many years of use, and interacts with lighting and shaders as you’d expect an object to in the real world. Stefan Morrell is a freelance digital artist living and working in New Zealand http://stefan-morrell.cgsociety.org O 056 | 3D WORLD 3D WORLD March 2007 FACTFILE FOR 3ds Max DIFFICULTY Intermediate TIME TAKEN Three hours ON THE WEB • Scene files • Textures • Screenshots ALSO REQUIRED Photoshop Life, as everyone knows, is dirty. It’s the accurate simulation of years of grime, scratches and contact with the physical worlds that can lend some essential realism to an otherwise pristine, antiseptic model BY STEFAN MORRELL Getting dirty 3DS MAX/PHOTOSHOP 3DS MAX/PHOTOSHOP TUTORIALS | Textures for realism TDW88.t_cyborg 056 TDW88.t_cyborg 056 16/1/07 14:12:10 16/1/07 14:12:10

Texturizar Cyborg

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Page 1: Texturizar Cyborg

ON THE WEB● The tutorial fi les are in the Stop Press section ofwww.3dworldmag.com

ften it’s the small details like scratches, scuff marks and dents that lend a certain realism to even the most fantastic objects. In fact, the everyday wear and tear that can only be

re-created with a careful mix of hand-painted textures and photographic reference can be the thing that really makes or breaks a model.

In this tutorial, we’re going to take an otherwise pristine droid

and give it a good visual thrashing. Imagine it is battle-scarred from

years of confl ict and abuse: we need to create the tell-tale signs of

everyday life. Its edges are faded and worn, scratches in exposed

areas have been fi lled with ground in dirt, and recessed areas have

become clogged up and decals have decayed over time.

It is often these touches that can make your model shine, adding

character to an otherwise lifeless object. And knowing where the

scratches, grazes and grime will be most effective can be an artform

in itself.

Using scene fi les available on the 3D World website, we will

begin by using the Render to Texture dialog to render an Ambient

Occlusion (MR) map. This is used throughout the texturing process,

both as an aid in knowing where to paint (and where not to) and

as a mask for fi lling new layers. This map can be multiplied above

the texture, offering free ambient occlusion without any extra

render overhead. It’s a technique commonly used in game texturing,

where real-time ambient occlusion would be too expensive to use

otherwise. We will also look into using a scratch brush to roughen up

the edges of the model. While the brush itself is important, painting

these scratches should be done in a very loose fashion, as if you

were roughly scribbling on paper.

We will create a base texture, followed by colour fi lls that use

the Use All Layers function in Photoshop, an often overlooked

feature that can quickly and effectively add much-needed variation

to a texture.

Finally, we’ll create a greyscale bump and refl ection/specular

map using a modifi ed version of the colour texture. Layers and the

blending options in Photoshop will help us create a hard-surface

texture that looks like it’s seen many years of use, and interacts with

lighting and shaders as you’d expect an object to in the real world.

Stefan Morrell is a freelance digital artist living and working in New Zealandhttp://stefan-morrell.cgsociety.org

O

056 | 3D WORLD3D WORLD March 2007

FACTFILE

FOR3ds Max

DIFFICULTYIntermediate

TIME TAKENThree hours

ON THE WEB• Scene fi les• Textures• Screenshots

ALSO REQUIREDPhotoshop

Life, as everyone knows, is dirty. It’s the accurate simulation of years of grime, scratches and contact with the physical worlds that can lend some essential realism to an otherwise pristine, antiseptic model BY STEFAN MORRELL

Getting dirty 3DS MAX/PHOTOSHOP 3DS MAX/PHOTOSHOP

TUTORIALS | Textures for realism

TDW88.t_cyborg 056TDW88.t_cyborg 056 16/1/07 14:12:1016/1/07 14:12:10

Page 2: Texturizar Cyborg

March 2007 3D WORLD 3D WORLD | 057

STAGE ONE | Rendering an ambient occlusion map

Load up the droid_start.max scene with 3ds Max 8. This scene contains a droid model that is UV mapped and ready for texturing. However, before baking an

ambient occlusion map, we need to change the render engine from the default scanline to mental ray. Press [f10] and scroll down to Assign Renderer. Click the Production box and assign mental ray as the renderer.

01

While in 3ds Max, we can render a UV template that can be used as a guide when painting in Photoshop. With ‘hullfront’ selected, add a UVW modifi er

(Modifi ers > UV Coordinates > Unwrap UWV) and in the modifi er options, click Edit. With the Edit window open, select Tools > Render UVW Template, and set both width and height to 1024. Click Render UV Template and save the image.

03

Create a new layer called Grime and, using any soft brush, lightly paint in some dirt along areas that might be expected to collect it. Apply a 10% vertical

motion blur to the layer, then paint over the grime again using a slightly darker shade and a smaller brush. Apply the same motion blur, change opacity on this layer to around 80% and set the Blend Mode to Overlay.

08

▲Textures for realism | TUTORIALS

Open the occlusion map and template in Photoshop, copy the template onto the occlusion map and change its Blending Mode to Screen. Change the

opacity of the Occlusion layer to 35%, then create a new layer and fi ll it with 50% gray (R:128; G:128; B:128). Name this layer ‘Base’, and make sure it is below the Occlusion layer. The template should be at the top of the stack.

04

With ‘hullfront’ selected, open the Render to Texture dialog (Render > Render to Texture) and, under the Output rollout, select Add > Ambient Occlusion (MR).

Change the map size to 1024 and Samples to 32: the default of 16 will render faster, but 32 will offer a fi ner result. Now create a path to save the rendered image and hit Render.

02

STAGE TWO | Creating the basic texture

Create a layer called ‘Scratches’. With the Brush tool selected, press [F5] to open Brush Options and select ‘Chalk 11 pixels’ from the Brush Tip Shape dropdown.

Activate Shape Dynamics if you have a tablet, select Scattering and apply the values: Scatter: 209% (Both Axes, Pen Pressure Control); Count: 4; Count Jitter: 36% (Control Off). Activate Texture with the default settings, and select Wet Edges.

05

Set the Scratches layer to Screen, and scribble the lines in very quickly and roughly. Imagine you’re rough-sketching something with a pen and paper.

They have to look natural and unplanned, after all. These lines are to simulate aging and general wear and tear along exposed edges of the droid, so keep them loose. They’ll also be used later for both bump map and fl ood fi ll masks.

06Because you want to paint these scratches in logical areas, such as along exposed edges, it’s a good idea to have the 3ds Max scene open, with an Unwrap

UVW modifi er applied and the Edit window open. You can now select faces of the model and see what parts of the texture they correspond to when viewing the UVs.

07

EXPERT TIPRender to textureTake time to explore the options in the Render to Texture dialog. Rendering different elements can be a great help when it comes to texturing: if we had, for example, parts laid out onto a UV template, we could assign colours to each part and render a diffuse map. Then the colour could act as a mask in Photoshop. The benefi t of rendering an occlusion map is to bake an expensive rendering effect into the texture. This way, you no longer need to use the more expensive rendering option. When laying out your UVs, try to avoid overlapping faces: these will appear as black in your baked texture..

i

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Page 3: Texturizar Cyborg

058 | 3D WORLD3D WORLD March 2007

Open the previously saved layered .psd, which we will use to create the greyscale bump map. Select the Scratches layer and invert it (Image > Adjustments

> Invert), then change the Blend Mode to Multiply. Select the PaintColour layer and desaturate it (Image > Adjustments > Desaturate) before adjusting the brightness so that the Paint Colour layer is brighter than the Paint Fill layer.

15

Create a new layer below the Paint layer and call it ‘Undercoat’. Hold [Ctrl] and click on the Paint layer. This will make a selection based on the previous

paint fi ll. Expand this selection by two pixels (Select > Modify > Expand) and, with the Undercoat layer selected, fi ll with a darker shade (R:124; G:88; B:6). You won’t need the All Layers option selected for this fi ll.

10

TUTORIALS | Textures for realism

Add an Adjustment layer at the top of the layer stack and call this ‘Global Colour’ (Layer > New Adjustment Layer > Color Balance), following the

values in the screenshot to create a global colour adjustment to all the layers in the stack. Save a copy of the .psd fi le before fl attening all the layers. Add a small amount (25%) of sharpening and save the image as ‘hullfi nal_colour.tga’.

14

STAGE THREE | How to create aged paint

Desaturate and adjust the brightness of the Undercoat layer so it is slightly darker than the Paintfi ll layer, then reload the selection saved earlier

(Select > Load Selection). Adjust the brightness of the Base layer – ensuring it’s light enough that the Scratches layer can be clearly seen. Invert the selection and lower the brightness of the Base layer so it is darker than both Paintfi ll layers.

16

Open photosource_Concrete.jpg and copy it to a new layer called ‘Grunge’. Set the Blend Mode to Soft Light and change opacity to 25 per cent. Turn off the

Template layer. Now create a new layer called Paint and select the Bucket Fill tool, check the All Layers option and apply the fi ll. These fi lls are affected by the contrast of all the other layers, so the scratch edges are not receiving any fi ll. To have a more subtle effect, raise the Tolerance value.

09

STAGE FOUR | Hullfront textures

In Photoshop, create a new layer called ‘PaintColour’ and select the soon-to-be red band. Turn All Layers back on and fi ll the selection with red. Move this new

layer above the Occlusion layer. Open Decal.psd, select the Barcode layer and drag it to your hullfront texture. Position it on the droid and change its Blend Mode to Multiply. Do the same with the other decals, using the Normal blend mode.

12Refer back to your 3ds Max scene with the UVW Editor open, and ensure you’re selecting the right areas for this step. We want to put a stripe of colour

around the edge of the droid, so select faces in the UVW editor and see which parts of the model they correspond to – the red areas in the screenshot.

11

EXPERT TIPAll LayersThe All Layers option can be very effective at quickly creating aged paint. The way it reads the contrast of all the layers means you can control where paintwork may be aged and worn away from everyday exposure. With our texture, we’ve assumed the edges of the droid are more worn, and the contrast offered by the Scratch layer means any fl ood fi lls we apply will avoid that area. All Layers can be used with several Photoshop tools and can create various effects. It’s also a good idea to keep this effect as subtle as possible, because it’s very easy to overdo things.

i

Make a selection of the ‘eye’ part of the template – refer to the UVWs in 3ds Max to ensure you’re selecting the correct area – and, with the Base layer

active, use levels to darken this area (Image > Adjustments > Levels). Save the selection for later use (Select> Save Selection). This process will add variation to the texture. For a little more detail, add some text to the circular part of the lens.

13

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Page 4: Texturizar Cyborg

March 2007 3D WORLD 3D WORLD | 059

Textures for realism | TUTORIALS

To see the fi nal settings, open the Droid_Final.max scene. You can examine how each texture map has been applied to the model using the Material/Map

Navigator. The high contrast of the greyscale bump map means bump strength should be kept fairly low in this instance, suggesting grazes rather than gouges. Lighting has also been kept fairly low-key, with the exception of some

omni lights placed inside the model to create a subtle sci-fi interior effect. For added realism, use the specular map as a refl ection mask, remembering that anything light on the map will cause more refl ection and dark areas will show less. You could even add some HDRI in your rendering if you have the time and horsepower. Try using the specular map as a mask for the HDRI refl ection. ●

22

STAGE FOUR (Continued) | Hullfront textures

[Ctrl]+click the Danger decal layer and create a new layer. Fill this selection with a shade that is slightly lighter than the Paint Fill layer, which should help to

sell the decal as a sticker on the surface on the model. Raise the opacity of the Grunge layer to 70% and convert the image to greyscale (Image > Mode > Greyscale). Save as ‘Hullfront_Bump.tga’ and ‘Hullfront_Bump.psd’.

17Using the same layered .psd, we can create a specular map. Select the Scratches layer, set Blend Mode to Screen and invert it back to white: this will ensure

this part of the model receives the most highlights. The rule with a specular map is that whatever is light will create strong highlights and whatever is dark will receive less: think about where dirt might collect for added realism.

18Lower the opacity of the PaintColor layer to 7% and PaintFill to 35%. The Scratches layer should be the brightest of all here but, essentially, we are trying

dull down all the layers so there’s not too much contrast. If you want more refl ection below the paint work, make the Base layer brighter. Lower the occlusion opacity to 20% and save this fi le as ‘Hullfront_Spec.tga’.

19

Smaller elements on the model such as bolts, screws and vents can be dressed with a generic tiling texture. This makes template creation easier, and

saves time laying out UVs for parts that are rarely seen. Import photosource_rust.jpg, and play around with it using fl ood fi lls with All Layers. Save the result as a Pattern fi ll for quick access (Edit > Defi ne Pattern).

21

Each of the main templates are painted using these techniques. The eye of the droid was done using a simple shape created with the selection tool in

Photoshop and applied to the self-illumination Material slot in 3ds Max. This is a pretty quick way to add a cool sci-fi feel to the fi nal scene.

20

STAGE FIVE | Wrapping up

TDW88.t_cyborg 059TDW88.t_cyborg 059 16/1/07 14:12:2816/1/07 14:12:28