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.
Direct Light Setup
We create a direct light with the values shown in the image shown to the right. You can follow the images to see where I have placed the light. But this is a matter of taste, and of course, it depends on the particular scene.
Press (Alt+B) and a window will appear (Viewport background). Use the values as shown on the screenshot. Then adjust the direct light as per the image above, because we need to match the direct light with the sun position within the HDRI.
Here is the image with the direct light; this provides strong but dispersed shadows. In the images shown to the right, different values have been applied to the V-Ray shadows with resulting levels of shadow sharpness.
The first image has a value of zero (0 with 32 subdivisions), giving it a focused look with no fading. In the second we have a value of 1 (1 with 32 subdivisions), and there is now some fading in the shadow borders. And so on till 4 with subdivisions. I personally use a value of 3.0 with 32 subdivisions most of the time.
Here we have the image with pure illumination provided by the HDRI, without direct light and the resulting soft shadows. Depending on what size lighting HDRI you use, and whether you blur it or not, you will find that you can achieve anything from very blurry shadows to quite sharp. However the larger your lighting HDRI, the longer your render times and the harder it will be to remove speckling/splotching artifacts.
Depending on the scene and the look we wish to achieve, we can work with or without direct lights. For example in this cloudy sky image, the sun is behind the clouds, giving a soft shadow look. Many of the HDRI Skies in the Hyperfocal range have the sun positioned on a cloud edge, allowing the artist to choose a direct light/hard edged shadow appearance, or a soft shadow appearance as if the sun is behind the clouds.
With a single sky you can alter the exposure level to create a number of different looks or atmospheres, as you can see in the images below. Or view the animation here.
For the materials, you can see the screen shots of the material editor below as reference.
In the reflections of the submaterial, we put a falloff (fresnel), this will make a more realistic-looking material. Just don’t overdo it.
Check out the floor settings…