What is Automotive CGI?
Automotive CGI is the art of rendering cars in a believable manner
either as full CGI scene or as backplate integration.
Made by Kristian Turner
Automotive Rendering in V-Ray General Overview | page 1
How to get Started?
Getting started in Automotive CGI can be as simple as downloading a
car model and starting with a studio setup. All that is needed is a 3d
package with a capable render engine.
Car Models:
Free Ferrari F40
Free Lamborghini Centenario
Free Nissan 380sx
Made by Carlos Pecino aka ColorSponge
Automotive Rendering in V-Ray General Overview | page 2
Why V-Ray over Arnold
V-Ray and Arnold are both extremely capable render engines.
However, Arnolds’ 3ds Max implementation is missing an interactive
render view which will immensely slow down the lookdev and light
setup process. Both of these engines are fully capable of creating
photorealistic CGI but for this task V-Ray will be faster to work with.
Automotive Rendering in V-Ray General Overview | page 3
Reference!
Creating photorealistic renders requires reference, loads of it! Having
a good reference setup before going into lookdev is crucial in making
sure you wont be slowed down at later stages by having to search for
specific reference.
Sources for high quality reference:
Google Advanced Image Search
Caricos
Paultan
Going outside and taking your own
reference!
Automotive Rendering in V-Ray General Overview | page 4
High quality model with good flow
What is flow?
Flow is simply the direction of the reflections over the car body. In po
lygonal models there will almost never be perfect flow but there is
good and bad models.
For more information read up on this article made by Ebalstudios.
Automotive Rendering in V-Ray Prerequisites | page 5
HDRIs
HDRI stands for High Dynamic Range Image. However, in this context it
is referred to as HDRI skydome textures used for lookdev.
High quality HDRIs are imperative to creating a shader that will look
correct in all different kind of lighting scenarios. A good source for
free HDRIs is HDRIHaven
Automotive Rendering in V-Ray Prerequisites | page 6
Moodboard
A Moodboard can be filled with anything from images to CG renders or
even illustrations. The point of making one is to set the tone and feel
of the artwork early on allowing the artist to work towards a focussed
goal and also aids as inspiration for direction. Not having a moodboard
will slow down the creative process and is not advisable
Moodboards can also be useful when receiving feedback as it will give
the viewer a concrete idea of what it is you’re trying to achieve.
Made by David Drbal
Made by Agnieszka Doroszewicz
Automotive Rendering in V-Ray Prerequisites | page 7
Having a good eye
Just like traditional artists, having a good eye is a big part of a look
dev artists’ job. Being able to perceive texture, colour and fine details
allows one to recreate them digitally. This can be supported by knowl
edge of the material properties through research.
This skill will come with time but can be sped up by critically looking
at your own work and letting third parties critique it.
Made by Tobias Eckerlin
Automotive Rendering in V-Ray Prerequisites | page 8
Ray-tracing
View
Ray
Shadow Ray
Image
Camera
Light Source
Scene Object
Made by Gilles Tran
Ray-Tracing is the rendering algorithm this
document will focus on and is used by most
industry standard offline rendering applications
such as V-Ray, Corona and Arnold.
Raytracing describes the procedure of casting
rays into the scene un til it intersects with a
triangle after which it recursively casts more
rays such as reflection, refraction and shadow
until stopped. Understanding how this algorithm
works allows artists to know the limitations of the
render engine they are using and when they
have to “fake” specific aspects to imitate
real-life.
Further reading:
GPU Gems
Nvidia Ray Tracing
Automotive Rendering in V-Ray Rendering Theory | page 9
How to set up HDRIs in V-Ray
Step 3: Load your HDRI via a VrayHDRI and set the
mapping type to spherical
Step 1: Select Vray as your render engine
Step 4: Drag the HDRI into the map slot as instance
Step 2: Create a VrayLight with the type Dome
Automotive Rendering in V-Ray Rendering Setup | page 10
What is ACES?
ACES (Academy Color Encoding System) aims to standardize the color
science used across a huge breadth of software and hardware tools,
and enable projects of all types to preserve the highest level of image
quality throughout the entire workflow, including production, post-pro
duction, distribution/presentation, and archiving.
Why should you use ACES?
ACES offers a much wider colour gammut and standardizes the work
flow along the pipeline.
Further Info:
ACES Discord
Standard sRGB Blender Filmic ACES
Automotive Rendering in V-Ray Rendering Setup | page 11
Where to download the ACES config file
To make ACES more easily accessible, there is some prebuilt config
files that require no knowledge of compiling files.
The most recent version of ACES at the time of making this document
(6/4/20) is 1.2, the download of the config can be found here.
Standard sRGB Blender Filmic ACES
Automotive Rendering in V-Ray Rendering Setup | page 12
How to set up ACES via OCIO in
V-Ray
texture slot in the dome light
Step 3: Open your VRay IPR and Disable sRGB view transform using this
button
Step 1: Load in your config.ocio
file into a VRayOCIO node and
connect your VRayHDRI to it
Step 4: Set the input Colorspace to ACES - ACEScg and the view
transform to Rec. 709
Step 2: Set the input ColorSpace
to Utility - Linear - sRGB and the
output to ACES - ACEScg. Then
connect the VRayOCIO to your
Automotive Rendering in V-Ray Rendering Setup | page 13
What is Lookdev?
Lookdev stands for look development and describes the process of
matching the look of a shader to a real life object, this is done through
a combination of texturing and shading by constantly looking at refer
ence and comparing it to the shader, once happy with it in one lighting
scenario, switch up the HDRI to ensure a consistent result throughout.
This is where good reference comes into play. Additionally, having a
good texture to work off of will in most cases lead to a better end re
sult which is why I decided to link resources for textures below:
Free:
•Texturehaven
•CC0 textures
Paid:
•Megascans
•FriendlyShade
•3D Collective Pack 01
Made by Toby Lee
Automotive Rendering in V-Ray Lookdev | page 14
Why Lookdev?
The reason why lookdev is a crucial step in creating photorealistic
car shaders is because it allows the artist to make sure the materi
al looks correct in different lighting scenarios which makes sure that
once placed into the custom lighting setup it will behave properly.
Made by Emil Dohne
Automotive Rendering in V-Ray Lookdev | page 15
Studio Lighting
Made by Emil Dohne
Automotive Rendering in V-Ray Studio Lighting | page 16
Light Linking
Before talking about the different types of lighting, light linking or in
clude/exclude should be mentioned. When photographing cars often
times photographers shoot multiple “exposures” (shots with different
lights turned on with a fixed camera angle) These are then blended to
gether in the post production stage where each part has to be manu
ally masked out.
In CGI there is light linking where one can set a light to only affect
some objects like the rims, car paint etc. which in V-Ray can be found
under the Options menu in the lights’ setting as an Exclude button.
This feature also works with 3ds max selection sets making it easy to
copy this to another light and only having to do the work once.
Made by Tomasz Szczecinski
Automotive Rendering in V-Ray Studio Lighting | page 17
Light setup and types 1
Setting up lighting for a studio render is all about trying to highlight
the shape of the car, dont be afraid of hiding certain parts to high
light others. Not everything has to be perfectly and evenly lit. There is
also no one way to light a car and while a 3 point studio lighting setup
might look ok in most cases it definitely isnt the end all be all. Setting
up lighting is an artistic skill which one can learn by trying to recreate
professionals’ lighting setups.
Firstly one needs to distinguish between different types of light sourc
es that may be used.
Spot lights:
rule) that are primarily used to get sharp highlights on the coat lay er and
make the flakes pop in a metallic car paint due to its high di rectionality
and intensity. See fig. 1 on what directionality is and how it affects your
lights and fig. 2 on the effect of small spotlights on the car body with a
metallic paint. These often break up the monotony of soft boxes but can
be used in combination with these
Figure 1 - Directionality of Light Sources
Figure 2 - Spot lights on car body
Typically small disc lights with a diameter anywhere from 1-5 cm (not a
Automotive Rendering in V-Ray Studio Lighting | page 18
Light setup and types 2
Soft Boxes:
Soft boxes are an array of lights that are diffused by a fabric creating
a mostly even distribution of light along a surface (fig. 3). In CGI one
can reproduce this by pointing a light onto a surface with a gradient
map applied to it. This will result in more gradation and a more natural
feel than if a light material is applied straight to the surface. See fig. 4
to see how this would be set up and fig. 5 on the rendered result. By
making the target a child of the plane it will move as the softbox does.
The light should only affect the softbox.
Figure 3 - Softbox
Figure 4 - Viewport
setup
Figure 5 - Rendered
result
Automotive Rendering in V-Ray Studio Lighting | page 19
Light setup and types 3
Streak lights:
Streak lights are lights that usually run along the side of a car to ac
centuate the shape and flow. In photography these are lights moved
along the side of the car in a smooth line as the shutter stays open for
multiple seconds which will result in a streak across the body. In CGI it
is easiest to create a rectangle light and make it as long as needed to
have a streak running across the whole body. A gradient can be added
here as well to blend it in better
Figure 6 - Streak Light
Automotive Rendering in V-Ray Studio Lighting | page 20
Background/Cyclo
The background of a studio render is quite simple, it is usually just a
chamfered plane.
One can get creative and change it up as seen in fig. 7 but generally a
“simple” setup will do. The material can either be a mid grey, reflective
floor or a combination of the two
Credit to Toby Lee
Figure 7 - out of norm studio
Automotive Rendering in V-Ray Studio Lighting | page 21
Basic Metallic Carpaint 1
Metallic car paints used to be reserved to higher end vehicles but
nowadays they are ubiquitous amongst all types of car models.
Creating one requires a flake map which can be downloaded here
(credit to Jeff Patton).
The setup itself is quite simple:
-Base Metallic Material
-Coat Material
-Falloff map acting as mix
In max that would look like fig. 8. The VRayTriplanar map is for scal
ing the flakes uniformly without having to worry about unwrapping the
object and the VRayNormal isnt required but sometimes it wont work
without. It is important that the Flakes map has its blur set to 0.01 in
order for the flakes to properly appear.
A common mistake is making the flakes too big, this is due to ref
erence images always having some degree of blur applied to them
be it motion blur or Depth of Field (DOF) which makes the flakes ap
pear much bigger than they actually are. In this setup the VRayTripla
nar map is set to the size of 10, all other values have not been changed
and do not need to be changed in most scenarios.
Figure 8 - Metallic Car Paint Setup
Figure 9 - Metallic Car Paint
Automotive Rendering in V-Ray Material Setup | page 22
Basic Metallic Carpaint 2
When the car paint is applied it is done in 2 coats relevant to Automo
tive CGI, the base metallic coat and then the clearcoat.
The base metallic coat in terms of CGI is a layer with a low diffuse val
ue and a lot of specularity. The Diffuse is usually a much darker colour
than the Reflect colour. To determine these values for any car paint
the reflection colour should be considered first and it shows the mid
tone values.
Glossiness for the base layer can range from .5 to 1 but needs to be
carefully lookdeveloped by matching lighting setups and comparing
results.
Figure 10 - Base Metallic Setup
IOR is usually between 2 and 3.5 depending on how metallic the ob
ject is, values above or beneath can also be considered but are not the
norm. Once again lookdev will ensure the right IOR has been chosen
The bump strength of the flakes is set to 5 in this example and should
hover around that value.
Automotive Rendering in V-Ray Material Setup | page 23
Basic Metallic Carpaint 3
The coat layer of the material is a simple material with the diffuse
value set to black and reflect to white, the rest of the values stay the
same.
The falloff settings used can be seen in fig. 11. The Front/Side colour
values should never be absolute and offset 10-15 on the RGB spec
trum. This is because there is no full absorption or passthrough on the
coat.
The mix curve should show a convex exponential curve. The first
point can be changed to a bezier curve by right clicking and setting to
Bezier-Corner. Once again lookdev to reach the final curvature shape
but this should give a good starting point.
The VRayBlendMtl is set up as default so all that needs to be done is to
drag the other materials in the appropriate slots as seen in fig. 8
Figure 11 - Falloff Settings
Automotive Rendering in V-Ray Material Setup | page 24
Basic Tire Material
Setting up a tire material can be quite simple, yet perfecting one can
be quite the task. Fig. 12 shows how basic one can be compared to a
more complex setup in fig. 13. However, with tire materials it does pay
off to put in the extra effort to composite together grunge maps as it
will make a noticeable difference, checking reference is crucial.
For a basic setup the diffuse of the tire should be almost black with
a value from 1-5 and the reflection colour a mid grey with a glossi
ness value of .3-.6 depending on wear and dirtiness whereas IOR can
be from 1.2-1.6. However, none of these values are absolute and you
should experiment during the lookdev period.
Figure 12 - Basic Tire Setup
Figure 13 - Complex Tire Setup
Figure 14 - Basic Tire Render
Automotive Rendering in V-Ray Material Setup | page 25
Basic Carbon Fiber
Carbon fiber is commonly used in high end cars and can enhance the
look and accentuate the car. In its setup it is almost the same as the
car paint shader except for its input maps which can be found here.
The texture files used were the normal map and the mask which is
plugged into the reflection channel with an opacity of 95. It connects
into the blend material with coat and falloff unchanged.
Figure 15 - Carbon Fiber Setup
Figure 16 - Carbon Fiber Render
Automotive Rendering in V-Ray Material Setup | page 26
Further Additions
Further additions that can be considered are orange peel and circular
scratches. However, keep in mind that these increase render time and
will only be visible in closeup renders, orange peel moreso than circu
lar scratches.
To achieve orange peel a simple noise as bump map to the coat will
suffice, scale and strength of which is paint specific.
For circular scratches a texture map found here, plugged into the
bump of the coat via triplanar will work.
Figure 17 - Circular Scratches
Figure 18 - Orange Peel
Automotive Rendering in V-Ray Material Setup | page 27
Grading & Retouching
Retouching and Grading should play a crucial part before publishing
your render.
Retouching can fix issues that were either unfixable in render or not
viable time wise. It can also help implement elements such as fog,
glare etc. in a timely manner.
Grading describes the practice of altering the colours to set a specific
mood. Generally speaking one can either cool or warm the image de
pending on the shot.
Figure 19 - Raw Render
wv
Breakdown of all different passes of fig. 21
Figure 20 - Final Render Figure 21 - Porsche 911 GT2RS Example
Automotive Rendering in V-Ray Grading | page 28
How to
While there is no definitive how to on grading there is certain ways of
doing it. The way I usually start is by changing the temperature and
then adjusting as required. To find out what is required the best way
to learn is through watching photographers’ breakdowns. A great re
source is Moe Zainal, this one specifically. Just like lookdev this skill
takes time to perfect but will pay off greatly when presenting the ren
ders on your portfolio.
RAW Renders to practice on
By Moe Zainal
Automotive Rendering in V-Ray Grading | page 29
Closing Words
This PDF was created to give back to the community and teach the
fundamentals of Automotive CGI. I hope this document helps everyone
improve as artists and grow.
If any questions arise I’d be more than glad to answer them, you can
contact me via email:
emildohne@gmail.com
Emil Dohne
Automotive Rendering in V-Ray Closing Words | page 30