First of all, here¡¯s a short description of what HDR is. It¡¯s a very usefull format that we encounter in different programs of Global Illumination (GI), like Vray, Brazil, and others, and now can be utilized by all the users of MAX 6.

With this tutorial, I intend to explain the basic process for creating good HDRI effects on models. You can experiment a lot with materials and different possibilities that are offered by using HDR Images.

The "dynamic range" of a scene is the Contast Ratio between its brightest and darkest parts. A plate of evenly-lit mashed potatoes outside on a cloudy day is low-dynamic range. The interior of an ornate cathedral with light streaming in through its stained-glass windows has high dynamic range. In fact, any scene in which the light sources can be seen directly is high dynamic range for it is high in Contrast.

A High-Dynamic Range Image is an image that has a greater dynamic range than can be shown on a standard display device, or than can be captured with a standard camera with just a single exposure. In other words:

HDR Images are made by combining multiple normal images of the same scene taken with different intensity levels, or are the result of creating a GI rendering. In practice, High Dynamic Range pixels use floating-point numbers, capable of representing light quantities of 01 to a million, and beyond. Low-dynamic range images (standard) usually represent pixels using eight bits per channel (RGB = 24bits; RGB+Alpha = 32bits), with pixel values ranging as integers only between 0 and 255 inclusively. Most of the HDR Images are presented in spherical environments, 360 º of liberty for work. It offers very interesting utilites, like perfect reflections in objects.

- We start working with HDR. Open 3DS MAX.

You only need one model. In my scene I have a women (extracted from a tutorial of MAX 5), and cameras (no lights). The image to the right is a quick render of my scene [F9].

- We will put an HDR Image to the background.

- For this, open the Material Editor [m] and select an empty slot.

- Click the icon for Get Material and select Bitmap from the list.

- Choose the HDR Image you like.

Another window will appear for configuring the HDR Image. You can select the intensity of the light, but the default is good. Click OK.

The HDRI thumbnail appears in the Material Editor, select under coordinates "Environ " and in Mapping, choose "Shrink-Wrap Environment, " - in this rollout maybe you have to choose another format depending of the kind of HDR you use.

Note: One error occurs here, the HDR Image appears rotated and in an incorrect position. For the solution it is simple: Select your scene (the model, the cameras and all the objects in the scene) and rotate it to the same direction of the HDR.

Now we will apply the HDRI to the environment map. Open Render > Environment. [8]

- Click the HDR Image and translate it to the Environment Map button in environment and effects window (Don¡¯t release the button).

- A window appears, select Instance and OK.

If you do a render of scene you will see the HDR Image in the background, if you rotate the camera you will see diferents parts of the HDR.

But now, it isn¡¯t very spectacular.

We can make our image reflect the environment. For this, we create a reflective material.

- Open the Material Editor, select an empty sample sphere.

- Click the Reflect slot, and choose Raytrace. You¡¯ll apply this material to the model.

- Render again. Now our model reflects the environment, try changing the diffues color of the sphere. (Black color will reflect the environment as a perfect mirror.)

This image appears very black because the hdri i choose are very dark.

Try changing the HDRI in the Material Editor. (We only have to choose the shpere that has HDR, click in Bitmap Parameters, and choose another HDR Image like the first steps. The image will change automaticaly in the Environment because before we selected Instance earlier.)

Render another preview to see the different results.

Now you can see the perfect reflection of the HDR. I put a Sphere with the same material because it let¡¯s us see the environment (materials are black color with Raytraced reflections.)

What happens if you want to see the HDRI reflect in the model but don¡¯t wanto to see the HDR Image in the background?

- Open environment dialog [8] and choose another image for background (bitmap, gradient rap, color, ...)

- In the model material click the buttom near reflect and change Raytrace for HDR Image that you like. Press F9:

At the moment, HDR Image are functional. But we can do more! We can utilize the HDR to iluminate the scene without any lights and create shadows only with HDRI.

- Create a simple white material and link it to your model.

- Create a Skylight and place it over your model.

- Open the Modify Panel (with Skylight selected)

- Now click on your HDR Image and drag it over the bottom in skylight parameters like you can see in the image. Select Instance and click OK.

- [F10] to open the Render Dialogue.

- Click in Advanced

Lighting and open the unique rollout that you see, and select light tracer.

- Put bounce to 1. You can augment the ray/samples to improve the quality, but the render time will increase.

- Render it, and... Woo!!! Interesting, no? The sphere in the window is the HDRI that I used to illuminate this scene.

Try to change the environment whithout changing the color of the model. You will see the drastic influence of the environment.

Same model, same material but with a different HDRI material for environment. Appreciate the difference with anterior render.

The same picture with the same hdr but with reflections; it¡¯s only reflecting the light that comes between the trees in the HDRI.

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