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Of all material surfaces, metals must be one of the most popular to appear in 3D design projects. Metals tend to be visually pleasing with brightly colored surfaces that will gleam when polished. They also exhibit fascinating surface detail due to oxidization and age-related weathering. Being malleable, these surfaces will dent and scratch to display their human interaction. All these issues mean that man-made metal objects are great objects to design outstanding material and texture surfaces within Blender.
It is possible in Blender to design metal surfaces using quite simple material setups. Although it may seem logical to create complex node-based solutions to capture all the complexity apparent within a metal surface, the standard Blender material arrangement can achieve all that is necessary to represent almost any metal.
Metals have their own set of unique criteria that need application within a material simulation. These include:
- Wide specularity due to the nature of metals being polished or dulled by interaction
- Unique bump maps, either representing the construction, and/ or as a result of interaction
- Reflection – metals, more than many other surfaces, can display reflection. Normally, this can be simulated by careful use of the specular settings in simulation but, occasionally, we will need to have other objects and environments reflected in a metal surface.
Blender has a vast array of tools to help you simulate almost any metal surface. Some of these mimic real world metal tooling effects like anisotropic blend types to simulate brushed metal surfaces, or blurred reflections sometimes seen on sandblasted metal surfaces. All these techniques, while producing realistic metal effects, tend to be very render intensive. We will work with some of the simpler tools in Blender to not only produce realistic results but also conserve memory usage and render times.
We will start with a simple but pleasing copper surface. Copper has the unique ability to be used in everything from building materials, through cooking, to money. Keeping up with a building theme, we will create a copper turret material of the type of large copper usage that might be seen on anything from a fairy castle to a modern day embellishment of a corporate building.
One of the pleasant features of such a large structural use of copper is its surface color. A brown/orange predominant color, when new, is changed to a complementary color, light green/blue, when oxidized. This oxidization also varies the specularity of its surface and in combination with its man-made construction, using plating, creates a very pleasing material.
To prepare for this recipe, you will need to create a simple mesh to represent a copper-plated turret-like roof. You can be as extravagant as you wish in designing an interesting shape. Give the mesh a few curves, and variations in scale, so that you can see how the textures deform to the shape. The overall scale of this should be about 2.5 times larger than the default cube and about 1.5 times in width at its widest point.
If you would prefer to use the same mesh as used in the recipe, you can download it as a pre-created blendfile from the Packtpub website.
If you create a turret-like object yourself, ensure that all the normals are facing outwards. You can do this by selecting all of the vertices in edit mode, and then clicking on Normals/ Recalculate in the Tools Shelf. Also, set the surface shading to Smooth in the same menu.
Depending on how many vertices you use to create your mesh, you may want to add a Sub-surface modifier to ensure that the model renders to give a nice smooth surface on which we will create the copper-plating material simulation.
In the scene used in the example blendfile, three lights have been used.
A Sun type lamp at location X 7.321, Y 1.409, Z 11.352 with a color of white and Energy of 1.00. However, it should only be set to provide specular lighting. It is positioned to create a nice specular reflection of the curved part of the turret.
A Point lamp type set at X 9.286, Y -3.631, Z 5.904 with a color of white and Energy of 1.00.
A Hemi type lamp at location X -9.208, Y 6.059, Z 5.904 with a color of R 1.00, B 0.97, B 0.66 and an Energy of 1.00.
These will help simulate daylight and a nice specular reflection as you might see on a bright day.
Now would be a good time to save your work. If you have downloaded the pre-created blendfile, or produced one yourself, save it with an incremented filename as copperturret- 01.blend.
It will also be necessary for you to download, three images that will provide a color map, a bump map, and a specular map for the plated surface of our turret. They are simple grayscale images that are relatively easily created in a paint package. Essentially, one image is a tiled collection of metal plates with some surface detail, and the other is derived from this image by creating a higher contrast image from the first. This will be used as a specularity map. The third has the same outline as each tile edge but with simple blends from black to white. This will provide a bump map to give the general slope of each metal plate. All three, separate, are available for download from Packtpub website as:
Once downloaded, save these files into a textures subdirectory below where you have saved the blendfile.
How to do it…
We are going to create the effect of plating on the turret object, tiling an image around its surface to make it look as though it has been fashioned by master copper smiths decades ago.
- Open the copper-turret-01.blend. This file currently has no materials or textures associated with it. With your turret mesh selected, create a new material in the Materials panel. Name your new material copper-roof.
- Change the Diffuse color to R 1.00, G 0.50, B 0.21. You can use the default diffuse shading type as Lambert.
- Set the Specular color to R 1.00, G 0.93, B 0.78 and the type to Wardiso with Intensity 0.534, and Slope 0.300.
That’s the general color set for our material, we now need to create some textures to add the magic.
- Move over to the Texture panel and select the first texture slot. Create a new texture of type Image or Movie, and name it color-map.
- From the Image tab, Open the image plating.png that should be in the textures subfolder where you saved the blendfile.
This is a grayscale image composed from a number of photographs with grime maps applied within a paint package. Each plate has been scaled and repositioned to produce a random-looking, but tileable texture. Creating such textures is not a quick process. However, the time spent in producing a good image will make your materials look so much better.
- Under the Mapping tab, select Coordinates of type Generated Projection and of type Tube.
- Under Image Mapping, select Extension/ Repeat, and set the Repeat values of X 3 and Y 2.
- This will repeat the texture three times around the circumference of the turret and two times on its height.
- In the Influence tab, select Diffuse/Color and set to 0.500. Also, set Geometry/ Normal to 5.00. Finally, select Blend type Multiply, RGB to Intensity, and set the color to a nice bright orange with R 0.94, G 0.56, and B 0.00.
Save your work as copper-turret-02.blend, and perform a test render. If necessary, you can perform a partial render of just one area of your camera view by using the SHIFT+B shortcut and dragging the border around just an area of the camera view. An orange-dashed border will show what area of the image will be rendered. If you also set the Crop selector in the Render panel under Dimensions, it will only render that bordered area and not the black un-rendered portion.
You should see that both the color and bump have produced a subtle change in appearance of the copper turret simulation. However, the bump map is all rather even with each plate looking as though they are all the same thickness rather than one laid on top of another. Time to employ another bump map to create that overlapped look.
- With the turret object selected, move to the Texture panel and in the next free texture slot, create a new texture of type Image or Movie, and name it plate-bumps.
- In the Image tab, open the image plating-bump-1.png.
- Under the Image Mapping tab, select Extension of type Repeat and set the Repeat to X 3, Y 2.
- In the Mapping tab, ensure the Coordinates are set to Generated and the Projection to Tube.
- Finally, under the Influence tab, only have the Geometry/Normal set with a value of 10.000.
Save your work, naming the file copper-turret-03.blend, and perform another test render. Renders of this model will be quite quick, so don’t be afraid to regularly render to examine your progress.
Your work should have a more pleasing sloped tiled copper look. However, the surface is still a little dull. Let us add some weather beaten damage to help bind the images tiled on the surface to the structure below.
- With the turret object selected, choose the next free texture slot in the Texture panel. Create a new texture of Type Clouds and name it beaten-bumps.
- In the Clouds tab, set Grayscale and Noise/Hard, and set the Basis to Blender Original with Size 0.11, and Depth 6.
- Under the Mapping tab, set the Coordinates to Generated, and Projection to Tube. Below projection, change the X,Y,Z to Z, Y, X.
- Finally, under the Influence tab only, select Geometry/Normal and set to -0.200.
Save your work again, incrementing the filename to copper-turret-04.blend. A test render at this point will not produce an enormous difference from the previous render but the effect is there. If you examine each stage render of the recipe so far you will see the subtle but important changes the textures have made.
How it works…
Creating metal surfaces, in 3D packages like Blender, will almost always require a photographic image to map the man-made nature of the material. Images can add color, bump, or normal maps, as well as specular variety to show these man-made structures. Because metals can have so much variety in their surface appearance, more than one map will be required. In our example, we used three images that were created in a paint package. They have been designed to give a tileable texture so that the effect can be repeated across the surface without producing discernible repeats.
Producing such images can be time consuming but producing a good image map will make your materials much more believable. Occasionally, it will be possible to combine color, bump, and specularity maps into a single image but try to avoid this as it will undoubtedly lead to unnatural-looking metals.
Sometimes, the simplest of bump maps can make all the difference to a material. In the middle image shown previously, we see a series of simple blends marking the high and low points of overlapping copper plates. It’s working in a very similar way to the recipe on slate roof tiles. However, it is also being used in conjunction with the plating image that supplies the color and just a little bump.
We have also supplied a third bump map using a procedural texture, Clouds. Procedurals have the effect of creating random variation across a surface, so here it is used to help tie together and break any repeats formed by the tiled images.
Using multiple bump maps is an extremely efficient way of adding subtle detail to any material and here, you can almost see the builders of this turret leaning against it to hammer down the rivets.