An outline of the techniques used for rendering an exterior scene using Autodesk 3ds Max and Chaos Group Vray. A HDR image will be used to light and reflect the environment and VraySun as the direct light source for a typical sunny day scene.
HDRI stands for high-dynamic-range imaging, which is a 32bit float image format that allows a greater dynamic range of luminance between the lightest and darkest areas of an image.
A HDR image holds enough information to light a scene, where as images such as JPEGs do not hold enough information to light a scene successfully. HDR images can produce good results, but the intensity is still not enough to give realistic hard shadows that would come from the sun. By adding in VraySun as a direct light source, the two methods combined will allow for easy control over time of day and various types of weather conditions.
Before I start, I would like to point out that I will be using a
linear workflow with a
gamma 2.2 setup within 3ds Max and Vray. I strongly recommend setting this up as it will improve many areas within your workflow. You can find an easy to follow, step by step guide
here. This tutorial will not go through the Vray render settings, but you can find a detailed explanation of how to set up the Vray renderer
here.
Finding the right HDR image
The choice for time of day and weather conditions will determine what HDR image is required. Within this tutorial it will be a sunny midday HDR image with minimal cloud which you can purchase and download yourself from
here. There are various shapes and sizes of HDR images out there on the web. You will need to make sure that the HDR image is a
360 degree spherical image and the higher the resolution the better. When a spherical HDR image has been applied as an environment, Autodesk 3ds Max wraps the HDR image around a sphere. None spherical HDR images will not wrap around the sphere correctly and produce incorrect results. Resolution matters only if you are planning to use the HDR image as a back plate. If the HDR image is only to be used to light a scene, you can get away with a much smaller resolution.
You would want a HDR image that has maximum sky and a hint of a horizon. Typically a HDR image is pure black under the horizon and therefore will not cast any light. In theory it will also be covered up by geometry.