Sci-fi cars in Maya and Maxwell Render: Desert Racer Part 2
Learn how Rory Björkman crafts this angular desert-racing sci-fi vehicle, from initial concept sketches to a Maya model ready for texturing
In this tutorial I will be following on from the modeling tutorial in last month's issue by texturing and compositing our futuristic desert racer. In particular we will be looking at how to create a variety of materials from pearlescent paint, carbon fiber and metallics using Maxwell Render's Material Editor. We will also go through the process of creating a foreground with rocks and trees, a distant background using the Maxwell Ocean tool, creating depth with the Maxwell Fog Emitter, and finally we will bring all of these elements together using HDR lighting.
Step 01: Base landscape
In Maxwell Render, the first step we need to take is to create a large expanse of background desert for our scene to take place. By selecting the Maxwell shelf we can access the new Maxwell Ocean tool. Simply click on this to generate an ocean plane. In order for the fog to work effectively, I resize the ocean to be very large in the scene at a 45-degree angle to our vehicle. In order to make the ocean look more like a sloping desert, we need to adjust the settings, and for the fog to dissipate naturally a low setting of 0.3 set to 'Constant' should give the effect we need.
Step 02: Foreground
As the foreground is closest to the camera we need to have much better detail. So first we need to create a polygon plane and add edge loops in line with the wheel direction, then extrude downward a small amount to create a natural-looking wheel groove in the ground. In order for the sand to match up with this, we must make and export a UV map for Photoshop. In Photoshop, place a tileable sand texture (see downloadable resources) and paint out the sand pattern as if it's been driven across. We'll apply this texture later in the tutorial.
Step 03: Making rocks using photogrammetry
Now I will demonstrate the process of making simple and effective rocks using 123D Catch.123D Catch is a free online resource from Autodesk where you can upload images of any object and automatically transform it into a usable 3D object!
The first step you need to take is to bring your dog for a walk and find some lovely stones. It's best to use stones that look like miniature rocks, so pick ones with rough details and crevices. Go to 123D Catch and follow the simple instructions.
After you upload the photos and export your model from 123D Catch, import it back into Maya and delete all of the unnecessary geometry. By pressing '6', you can preview the texture. That's it - instant rocks!
Step 04: Image-based lighting (IBL)
In the project files for this tutorial you will be able to download this outstanding extra-large HDR image, supplied to us exclusively by doschdesign.com. Dosch Design supply artists with an array of products including beautiful high-quality HDR images, so I am very grateful to Sebastian Dosch for letting us use this image.
To access this image we need to enable Image Based Environment in the Maxwell Render settings window. I find an Offset U value of 25 and an Offset V value of 5 work nicely to get the most from this HDRi. Of course, this is a matter of personal taste.
Step 05: Lighting alternatives
In this step we will take a look at some lighting alternatives. If you do not have access to the Dosch HDR image you can find some nice free alternatives online. One such place is HDRLabs (hdrlabs.com) which offers a wide range of free quality HDR images.
Another great alternative is to use the built-in Sky Dome in Maxwell Render. The advantage of using the Maxwell Sky is that you have a huge amount of control over the lighting itself, such as time of day, atmospherics and location. This can be accessed in the Render settings under the Maxwell tab.
Step 06: Adding foliage
In this step we will use a free sample from Xfrog to populate our scene with foliage. It's time to add some trees into our scene. For this there's no better place than Xfrog. As this is a desert environment, I've chosen the Queen Palm set which you can download for free from the Xfrog website (xfrog.com/product/TR19.html). You can choose to download the models in multiple formats, but Maxwell is not one of those formats, so I will supply the Maxwell Materials for this tree in the downloadable project files. Next, place the trees into the scene to fill any spaces in the composition and apply the materials as labeled.
Step 07: Exporting for MARI
For painting our model in MARI, we first need to make and lay out the UV tiles. MARI supports multiple UV tile layouts, so I will separate the model into its material components, i.e. metal, wheels, paint surfaces, and so on. This will make it easier to select objects, paint objects of the same material, and apply an overall dust texture later.
In the Maya mesh settings, I use the smooth setting with a value of 2, with Preserve > Selection Borders checked. In the UV layout panel, under the UV Texture Editor Grid Options, set the length and width to 10, and the number of subdivisions to 2. This should enable you to preview the full set of UV tiles for MARI.
Step 08: Making sand masks in MARI
To create the effect of sand in crevices, first go to Objects > Ambient Occlusion. Then in the Channel menu, create a new layer and select Geometry > Ambient Occlusion. The ambient occlusion will be created as a procedural layer, so to rasterize this, right-click and select Merge.
By selecting various parts of the geometry, we can use grayscale images to paint natural sand streaks on the AO layer. Try to imagine that what's black will be sand. When you're happy, right-click the AO layer and navigate to Export. It's good practice to rename your exported files according to where they are on the vehicle.
Step 09: Applying the carbon fiber texture
First we will select our geometry and open the UV tab; this way, we can paint flat. Import the file 'carbon fiber.png' (provided in the downloadable resources) into the image plane and drag it onto the work area. At the top, select Repeat so that the texture will repeat at the edges as we paint. Alternatively, by selecting Stamp, you can fill the entire screen with once click. (Note that this will affect all geometry on the screen at the same time, so make sure only the panels we want carbon fiber on are visible.)
Step 10: Interior texturing
I apply the material for the seats in the same way I applied the carbon fiber. I have supplied the seat texture for you in the project files. When applying the seat texture, ensure that the seams and fiber direction run complementary to the seat itself, as it will look much better in the final renders. We can also import images to apply as patches to the seat belts or wherever you wish. Note that it's good practice to apply each material in a separate layer within your channel layer and label it accordingly.
Step 11: Maxwell material overview
In the Maxwell Editor we can create multiple layers of various opacities, and within each layer we can also create BSDF layers, which can contain bump maps, diffuse textures, gloss maps, emitters and displacements. The best workflow is to create the base BSDF first by plugging your image into the Reflectance node. You can lower the Roughness of this to achieve a matte or gloss finish; whatever color or image is plugged into 'Reflectance 90' will become more dominant the lower the Roughness is brought. In the upper layers above this, we can plug in a solid sand color and this can be controlled by an opacity mask made earlier in MARI (or any grayscale image). This way we can layer sand on top of our materials below.
Step 12: Maxwell material overview
metallic paint: For making a nice metallic paint, we need to start with a deep ruby base with a Roughness of 50. Above this, make a new layer and set it to Additive (this is signified by an 'A' on the layer). On this layer, we'll make the Roughness 25, put a red color in Reflectance and orange in Reflectance 90. Reflectance 90 should always have a lighter color than Reflectance for better falloff light.
Then make another Additive layer above this for the glaze coating, check "Force Fresnel" and lower the Roughness to 0. You can add a new layer above this again, like in the carbon texture, if you want to make the sand mask.
Step 13: Maxwell material types
A great way to understand the materials and get started on any new material is to use the materials wizard. When you create a new material by selecting the Global Parameters tab, you can access a range of basic material types under the Type Menu. Alternatively you can access either the Browser at the top and search the thousands of ready-made user materials, or the Local Materials which are made by Maxwell. Always remember when stacking BSDF layers to make sure they collectively add up to 100 to get true results.
Step 14: Maxwell material basic
We can make any image into an Emitter material in the Maxwell Editor. First you must convert that image in Photoshop to a 32-bit format under the Mode tab in the menu, and then save it as an Open EXR. When you create a new Maxwell material by right-clicking on the layers palette, we can 'Create Emitter', and under Type, select 'HDR Image' and plug your image into the material. From here you can also adjust the intensity. I will supply the materials used in this project for you to analyze.
Step 15: Adding fill and kick lights
In this step we will add a fill light and a kick light - also known as a 'kicker' light, a secondary light source that adds extra dimension to the darker side of the subject. One of the great features in Maxwell Render is the Multilight function, which allows us to adjust the lighting intensity and color, post-render.
The first thing we need to do is to add two polygon planes with the normals facing our vehicle. We will then need to apply a Maxwell emitter material to each plain. If you use the FIRE window, you can adjust the intensity and color of these before committing to a final render. These lights will give us extra control over the outcome of our scene.
Step 16: The Maxwell Multilight feature
Before you render your scene, you must enable the Multilight feature in the render settings. You can enable it to adjust either light intensity or both intensity and color. Once your render is complete you can slide the dials in the Multilight window and update the scene by hitting Refresh. If you like the image, make sure to save it before adjusting the lights again. This way you can have multiple versions with different lighting from one render. In our final scene I will just use this setting sparingly to bump up some shadows and highlight the paint sparkle so that it looks natural. After taking the final image into Photoshop to tweak the levels, add some atmospheric dust and paint extra sand details under the tires, the car is complete.