Product Render with Vray
Product Render is one of the task which require advanced technical knouledge to be able to control the result, no matter what you are looking for. In this article I am trying to present the necesary knowledge to confront the challenges when you make a product render, as some techniques to make easier this task. For this article I am using Vray 3.00.03 y 3dsmax 2014 16.0 SP5
Creating a cyclorama
A cyclorama is a resourse widely used by photographers when doing product shots, is simply a wall that joins the floor through a soft circular shape, to avoid the corner and make the illumination soft in this spot. To create it I am going to make a line and apply a lathe modifier, only creating 40 degrees of the lathe. The idea of creating the cyclorama with a lathe instead of a extrude is to avoid the most the reflection of the cyclorama on our product. I will start rendering a sphere with a VrayMtl configured as plastic, the cyclorama will have a VrayMtl in light gray.
In terms of illumination there are many ways that a product can be light, but I will start with VrayLights in plane mode, to create area shadows. With this we can generate the main lighting of the scene. It is important to note that this lights are only generating diffuse light, it is necesary to turn off the reflection and specular components to avoid generate reflections and gloss on the object, aside of this Vraylights need to be big enough compared to the product so you can se the area shadow, the multiplier value of the light I will put it in 80 this is because I am using a Vrayphysical Camera that it will help me to control lighting, the only parameters that I am changing on the camera are vignetting (Turned off ) and white Balance in neutral.
Next I will turn on Global Illumination, I will use the default vray configuration since the purpose of this article is not to talk about GI quality, also I will change the color mapping mode to color mapping and gamma, and I will check that the Gamma value is set to 2.2.
This render, in spite of having the basic lighting elements, lacks a general illumination surrounding the object, this lighing will generate softer shadows arround the object and a uniform lighting. To create it, I am going to turn on the GI environment option on the environment rollout of the Vray tabin the Render Setup Settings, I will also increase the intensity value to 15 because it was unnoticeable with the original value of 1, and change the color to white, by doing this it simulates a dome arround the scene that generates white lighing and creates soft shadows because it is only GI lighting.
At this point lighting has been finished the most important when creating the lighting is to have soft shadows, this is depending on the look that you are searching but in general soft area shadows will make the product look professional, you can also add more lights, in case you require a diferent look or more shadows.
Specularity Reflection and Glossiness
Glossy effects can be generated in several ways one of them is with VrayLights, it is very important to understand how this values interact with Reflection Glossines Values and with the specularity and reflection component of the light and the material.
A VrayLight Generates 3 lighting components, Diffuse, Specularity and reflection, this is why in lights that I wanted to light the scene, I turn off the Affect specular and Affect Reflections componens, but with lights that we want to create shine we need to only use affect specular and affect reflections so the diffuse component does not affect or previous configured illumination.
The specular and reflection componets are linked to the material glossines, a vray material with a low value in glossiness will generate an intense specular component, and a low reflection component, and vice versa, a high value of glossiness will generate a low specular component and an intense reflection component.
The value of Reflection Glossiness has a a value above it called Hilight Glossiness that by default has an L aside turned on which means that both values are linked. The hilight Glossiness Value is the glossiness that defines specularity, and the glossines value is the one that defines reflection, this values can be diferent at any point if you turn off the L. This way you can manipulate specularity and reflection independently, the next image shows the result of apply 2 more lights to our scene one with specularity and one with reflection and modify the material so the value of Hilight Glossiness is lower thant the Reflection Glossiness.
Reflections can also come from an HDRI, we can use anything but one of my favorites is one from Paul debevecs site www.pauldebevec.com/Probes/ called Building cross here is the direct download link . It is important to download the image in HDRI format and put it inside a VrayHDRI changing its mapping type to match the HDRI we are using , in this case is Cubic Environment, this map we will plugit to the reflection/Refraction Environment Channel in the render Setup Dialog (F10), also it is important to notice that we can modify the intensity of the reflection in the Overall Mult Value or in the Render Mult Value of the HDRI till we get the intensity in the reflection that please us, and also rotate the map in the horiz. Rotation and Vert Rotation options.
There are times when a product render needs to avoid the floor reflection on the object, we can acomplish this by changing the properties of the cyclorama to visible to reflection/refraction. we can get this object properties dialog by selecting the object(s) and giving a right click on the viewport, and selecting Object Properties from the quad menu that displays.
Beside doing color correction and other things in postproduction some times is useful to get rid of the background of the image so we can put a solid color or create an background gradient. For this purpose I am going to use the VrayMtlWrapper, with this material we can eliminate the background and keep the shadows if it is properly configured. The original material of the cyclorama will be connected to the BaseMtl on the VrayMtlWrapper, so this material will be used for GI calculations and reflections and refractions. I will turn on Matte surface option to start using the matte properties, this will avoid the material to be seen on the render, and I will also modify the alpha contribution value to -1 this will make the object to apear transparent on the alpha channel, finally I will turn on Affect Shadows and Affect Alpha this will capture the shadows on the alpha channel. It is very important in this step that the normals of the object to be right, pointing on the viewers direction, you can correct the normals with a Normal Modifier or with the option of invert normals on the lathe modifier. To see the direction of the normals you can use an Edit Normals modifier.
To finish I will render the image to an openEXR format 32bits and RGBA output and I will open it with Photoshop.
When importing on PS CS6 and later versions PS shows a dialog box asking if the alpha channel will be use as an alpha channel or as transparency, I will choose transparency to make it easier and then I will change the background with a gradient.
Next I will present some images rendered on this stage as a zip file with the max file created on this tutorial. On this scene you just need to import your product and render it. There are many ways to present a product and you can change any of the steps to suit the look that you desire but this are the main steps and techniques that you can use to have control on your render.