HDRI-max-English.pdf

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DOSCH DESIGN TUTORIAL

Using HDRIs in 3ds max

A Step-by-Step Guide

This tutorial show you how to use

HDRIs in 3ds max by using Vray

or Brazil r/s .

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Step 1

Things you will need for this tutorial.

3D Studio Max 4.xx or above

Vray or Brazil r/s

HDRI files from one of the

Dosch Design HDRI collections

the scene files delivered with this tutorial

About HDRI

There are two types of images. Low Dynamic Range

Image(LDRI) and High Dynamic Range Image(HDRI).

The first one comprises "normal" bitmaps [like JPEG,

TIFF, BMP...], bitmaps which have 8 bits per pixel, with

values between 0-255 [in RGB mode]. Which means that

there are only 256 levels of luminosity, which doesn't

cover by far the range that can be captured by a real

camera, with different levels of exposure.

On the other end we find HDRI, whose values can get a

lot higher then 256. The main feature is that the value of

each pixel is proportional with the quantity of light on

each pixel. Basically, instead of just storing colors on the

screen like normal bitmaps do, the HDR format stores

the quantity of light per pixel. Meaning we can have

more then 256 levels of luminosity.

Let's Start

File>Open hdri101_start.max. This is the scene we'll

use. It has standard all polys and standard materials.

This is a render with Max's standard Scanline Renderer

with only ambient lighting. (Image 00)

Not too pretty, is it?

And this is what you will get when using

Image 00

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Vray

Brazil r/s

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Vray

First thing let's open the scene. File>Open and choose

hdri101_vray.max . This is a scene with materials already

assigned to them. Basically all that was changed is a

Vraymap in the reflection or refraction slot.

But before that, go to Rendering>Render or just pres F10 to

go into the rendering settings menu.

Tip. Learn to use Max's shortcuts. They are real time savers.

All around this tutorial shortcuts will be highlighted in green,

so make yourself a favor, learn them.

Now in the settings menu, go to the Current Renderers tab

and press in the Production slot you should see something

like Default Scanline Renderer. Press the Assign button next

to it then choose Vray. (Image 01)

Now click on the Image Sampler tab and select Adaptive

Subdivision . Select Indirect Illumination(GI) and select On .

Select Irradiance Map and at Min Rate/Max Rate use -6/-5.

These settings are good for test renders. The render times

will be short, which is a good thing especially for doing GI

and material set-up work. For final rendering I recommend

using Simple Two-Level , under the Image Sampler tab, and

for Min Rate/Max Rate use -3/0 or -2/0, depending on the

scene. Also use Clr tresh: 0.3, Nrm tresh:0.25, Dist tresh:0.1

and HSph subdivs at 40. Be prepared for BIG rendering

times. But don't be afraid to EXPERIMENT.

Environment Mapping

Now let's map the environment. There are several ways of

doing this. I'll tell you in short then detail them one by one.

First there is the standard Max Environment mapping . Then

we have Vray's own environment mapping. And here we can

use either a VrayHDRI map, or a simple Bitmap . The latter

option requires the hdri.bmi plugin from the Splutterfish

website. It's free. All it does is enables Max to import .hdr

files.

Image 01

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Standard Environment Mapping

Go to Render>Environment or just press 8 . In the

Environment Map slot click where you see None (Image 02).

Then browse to the location of HD008LL.hdr and select it.

Then press Setup (Image 03).

A new window will pop up and we get a histogram of the

luminosity values of the selected image.(img05.jpg)

Under it we find White Point value, controlled by a spinner.

This White Point controls the luminosity, actually the range

of light values the image can take. As I said earlier, Max

doesn't use floating point images so with this setup window

we are actually converting floating point images to standard

images. It does that by setting a White Point , which is the

point with the highest luminosity value. Any value after the

White Point is considered as being pure white. It's also

known as the clamping value or point.

Image 02

Image 05

Notice there are two values for the White Point . One is Log . ,

the logarithmic value and the Linear one. We increase the

spinner until the vertical red line is at the end of the

histogram values. Now look at the Linear value. Write it

down somewhere. Press Ok then Open .

Image 03

Open the Material Editor , open the Environment Map you've

just created. Open the Output slot and under RGB Level

input the Linear value you wrote earlier. From the image you

can see I used a higher level. That is because through trial

and error I decided the image looked better like this..

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