An Advanced Vray HDR Tutorial:
This is a slightly more advanced version of a Vray and 3dsmax HDR lighting setup. You’ll obtain better images than using the standard HDRs provided all by themselves. The first tutorial basically used one of my HDRs for everything. Now I’m going to show you how to split the High Dynamic Range images up so that you get better looking results and also so that the rendering process itself is more efficient in terms of memory and processing. It does take a little bit more time to set up however, and that is why I generally skip the first two tutorials/methods listed here and simply use the sIBL application instead as it automatically takes care many of the HDR insertion steps below. But if you don’t use sIBL, than you may find this information helpful.
The first few sections below (Steps 1 – 8) are a copy and paste from the previous tutorial on setting up your basic scene and using Linear Workflow (LWF.) If you’ve followed and understood the previous basic tutorial, then you may want to skip directly to Step 9 instead.
I am going to outline a few easy steps for using High Dynamic Range Images with Vray 1.5 SP3 and 3dsMax. This should apply to any HDRs you may have in your texture and lighting libraries. Most of you are probably already aware of most of these basic steps but for those that don’t, I will try to walk you from the beginning without going into too much detail and theory.
1) First, you will want to use Linear Workflow for more accurate color reproduction. Technically, you do not have to use LWF but you will often find yourself manually adjusting your images in post-production in order to get them to look realistic. This is true regardless of any scene using Vray. You will want to open up Max and browse to the top menu bar: \Customize\Preferences\Gamma and LUT\ and set the following parameters:
2) It’s generally good practice to set your scene dimensions to real world units. Again, this is not necessary but it is very helpful for reproducing more accurate lighting conditions as well as working with both architectural and product models. I almost always try to approximate the dimensions of my models even if the measurements aren’t completely accurate. It is a very good habit to get into. Browse to: \Customize\Units Setup\ and set your parameters (I often use US Standard because I work with many US-based architects):
3) Insert your model into the scene or create a new item such as a teapot in the top viewport. I’ll set the teapot radius to 1′ as an example.
4) Right click your model, select move from the context menu, and zero out the coordinates in the XYZ boxes at the bottom of your screen so this way your model is perfectly centered. Again, this isn’t necessary but it’s? just a good habit if you’re a modeler.
5) Create a plane in the top viewport near the center of the scene. Usually, I start to drag out the object as I’m holding the control button down – this way the plane is created from the center instead of an edge. I usually zero out all of my objects. Your scene should look something like this:
6) VRay works best if you use Vray materials instead of standard ones. On larger scenes, it can easily shave off several minutes of rendering time. I always avoid non-Vray materials whenever possible. Create a plain white Vray Material and apply it to the plane. Please note with LWF, pure white colors can cause extremely long render times. I usually reduce my white values by several points out of habit. In this case I’m setting it to 254:
7) Create another Vray material of your choice. For this example, I’m going to use a basic chrome type of material as it will show some good reflections and apply it to your model/teapot:
8) Create a VrayPhysicalCam in your scene like below:
Hit ‘c’ after laying out your camera in order to view the scene as the camera sees it. You may want to adjust the position of your camera with the rotation controls in the lower right-hand side of your screen. My Physical Camera settings for my files usually render nicely at F1.2. Sometimes I also set the White Balance settings to neutral.
9) Here is the part that diverges from the previous “simple” Vray HDR tutorial and we get a little more advanced.
Now we will add the HDR to a couple different slots in the Render Setup window. Open the Render Setup window if it isn’t already: Top Menu Bar \Rendering\Render Setup…\.? Under the Render Setup window, there should be a tab called: Vray:: Environment. Open that part and where it says GI Environment (skylight) override, check the on button and where it says none, and browse to your HDR file located on your hard drive.
With this, you are essentially instructing the 3d program to light your 3d model with this file. In reality, you really don’t need a large HDR to light your file. In fact, you can save memory and processing by loading in a very small version/copy of original HDR that is blurred. Here, I used a 137 KB HDR that’s been downsized from the original 8,000 x 4,000 pixels to 360 x 180 pixels and blurred in Photoshop and resaved with a different name – usually renaming it with the suffix “*_env.hdr” Compare that to the 88.3 megabyte file which most people would use!!! Of course, you could just use the original HDR instead. However in a complicated scene, the rendering may go a lot slower – even running into memory issues or even worse a crash.
10) Now, you’ll want to do the same to the Reflection/refraction environment override in the same window. This time, I won’t use a blur, but I’ll use a much smaller, resized version of the original HDR. In this case I’ve resized the original HDR down from 8,000 x 4,000 pixels to 1,500 x 750 pixels. I’ll rename it with the suffix “*_env.hdr” The file size is now 3.4 MB compared to the original 88.3 megabytes. Again, you don’t have to if you don’t want to – you can still use the original file.
Here is how my Steps 9 and 10 look:
11) Go to your main Environment window \Rendering\Environment…\. In this case, I’ve saved out a tonemapped version of the original HDR to .jpg. I’ve kept the size 8,000 x 4,000 pixels, but the file size is drastically smaller while remaining crisp. This will be your actual background image.
With the libraries on the HDRSource website, you can just simply use the tonemapped .jpg file which I have provided. Tonemapping is a completely different step/process than anything discussed here, but if you’re really interested, you can search the web for plenty of information on how to tonemap HDRs yourself. Tonemapped images will look much better than using an original, plain HDR as a background image.
12) Now we are ready to run a test rendering. Open up your rendering setup window from the top menu bar: \Rendering\Render Setup…\ (shortcut =F10.) I’ve provided a very efficient test rendering setup below:
13) Select your Camera in the viewport or hit the ‘c’ key after selecting your viewport if it isn’t already. This should switch you to your camera view. Now you are ready to make your first rendering test. Hit ‘render.’ Here is my result using my test settings and default camera values:
13) The scene may look perfect, too dark, or too bright depending on the HDR used. There’s several different options you have at this point. You can always change the camera angle, change the F-Stop (F Number) of the camera (lower number for a brighter scene and vice-versa), or adjust the brightness and contrast in post with a program like Photoshop. Also note that you may have vignetting turned on in the camera which may darken the image corners. And last but not least is your camera White Balance which may lend your image a certain tint. I usually turn mine to neutral but sometimes the daylight settings (default) works well.
14) As an alternate option, sometimes I add a Vraylight set to sphere (which I’ve done above), No Decay checked on, Affect Specular checked off, Invisible turned on, and slightly tinted yellow to my scenes in direct position of the sun. This will add a more defined shadow as well as a little bit more overall tint to your scenes. You may have to dial up and down your light multiplier. This is really dependent on the HDR being used as well as the look you are going for.
15) If I wanted to spend more time on this, I’d probably bring the final image into Photoshop, add a little more contrast, and give the scene a little more saturation in order to boost its impact.
16) Keep in mind with HDRs, that you can rotate the camera and the background will change according to the angle you use. So out of one HDR, you could potentially obtain many useful renderings.
17) When you are ready to render the final image, adjust the ‘Width’ and ‘Output’ size under the ‘Common’ render tab to your liking. You may want to turn on the ‘Antialiasing filter’ under the ‘Vray’ render tab for sharper edges. Under the ‘Indirect Illumination’ tab, you can change your ‘Primary Bounces’ to ‘Brute Force’ (leave default) or ‘Irradiance Map’ (change to medium or high settings) and set your ‘Light Cache’ to around 1500 ‘Subdivs.’ Last but not least, under the ‘Settings’ tab, you can dial up the ‘Global subdivs multiplier’ to something like 2 or 3 (even higher) if you want to increase the overall rendering settings. Please note that all of these settings will increase rendering times as well as quality.