Architectural Visualization with HDRI Skies and Vray by Paco Morales, Mexico
In this tutorial, we will illuminate an exterior architectural scene with help from Vray and a HDR image (High Dynamic Range Image, or HDRI for short) from Hyperfocal Design.
Using 3dsmax and HDRI Skies with the V-Ray rendering engine will enable us to create super realistic results. Our HDR sky image will be used to light our scene and to create realistic reflections with a high level of realism, and with great ease of use. Conventional light rigging schemes can eventually achieve similar results, but with lots of time wasted on experimenting and tweaking. And time is money.
We will use the V-Ray rendering engine, adjusting several parameters along the way to obtain nice shadows, materials, caustics, etc. V-Ray has proved itself to be a market leader for speed, ease of use and stunning lighting capabilities.
The first thing we will do is download the necessary files to start building and setting up the scene, and provide it with lighting and material information. This is a step by step tutorial, with lots of images to help grasp the general workflow idea. After all, one good image is better than a thousand words! You can download the 3d file from here.
For the sky, if you do not have one of Hyperfocal’s HDRI Skies you can of course use one their free HDRI samples, which can be found in http://www.hyperfocaldesign.com/free-textures/
You could use a spherical HDRI for your scene, however you will usually find you have unwanted objects such as buildings or trees which do not match your scene. You may also get unwanted lighting, color and reflection information. We will use one HDR image in several different sizes - one small image for the illumination and larger ones for the background and reflections.
Note: This is not always the case, do some tests before committing an HDRI for a background. Depending on your scene, you may have little in the way of reflections, and you may not need a dynamic HDRI background. In this case just resample the HDRI Sky to 8bit at the exposure level of your choice.
The resolution of the HDRI for the background and reflection mapping is larger than that of the lighting image. For lighting we just need to get the general intensity, color and direction of the illumination from the image, whereas for the reflections, we need lots of detail showing. The higher the detail, the more realism in our final render.
First disable “Default Lighting” under Global Settings and delete any lights you have in the scene.
Now we load the HDRIs into the material editor; one for the illumination, one for the reflections, and the other for the Environment. Follow the instructions for the lighting HDRI below and then setup your reflection and environment HDRIs in the same fashion.
I like to handle the large background/environment HDRI independently, as this way you can adjust the background exposure level to suit your taste, without affecting the reflections or lighting.
In other words, you can make the sky HDRI look brighter or darker without over or underexposing the scene, this is good, as you have more overall control over the scene this way. This is effectively a way of tone mapping within your scene.
Note: Setup your white and black point as shown below, but don’t clamp the HDRI, otherwise you will lose the valuable illumination information. Clamping the sun may reduce splotching and speckling artifacts in your final render, however you are better off resizing or blurring your lighting HDRI. You will need to adjust the RGB level to match your white point figures.