Glass apple in Vray and 3D Studio Max Tutorial

Lighting: (GI/Photons and other such cool toys)

This is arguably the most important aspect of this scene because so much of the final effect that the materials will have is down to the lighting,

For this scene I am gonna use a Single point lighting system and a filler GI lighting setup. For anyone unfamiliar to Vray I will explain a bit about the

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Vray Light

This is a special vray light

Like this

Now turn the multiplier up to 5.
 
We will tweak the size and position latter once the GI has been configured and we can get an idea of how the scene lighting will look

GI (Global Illumination):

Although the Plane light is our main point light source we will need some filler lighting from the environment, If you were to render the scene now it would look like this.

As you can see the lighting is not yet right, its way too dark, the Vray light source is seen as the only light source so the object is only illuminated from one point, the GI lighting setup is currently disabled, Lets summarized the GI or Indirect Illumination.

The GI calculations are very different to direct lighting used in Max or even the default lighting seen in the above render. In direct lighting a photon (light particle ;)) is sent out from a light and as soon as it hits an object it illuminates it but stops, it does not bounce around the scene as real light does. This is where Global Illumination comes in, it calculates not only the first hit (called the Primary Bounce) that a photon makes with an object but also the second and subsequent bounces (Called secondary Bounces). In GI as in the real world every object reflects light in a certain quantity depending on its reflectivity and brightness, so a self illuminated object in a scene lit with the Vray GI algorithm will be seen as a light source. In this way the lighting is very true to life but this comes at a price in the form of rendering times. There are countless measures you can take to optimize the scene to save on rendering time but for this tutorial we will stick to a brute force method of calculating the GI.

Setting up The GI Engines:

1. Once the Vray Renderer has been enabled in the Render Tab, Click on the Renderer Tab and Scroll down to Indirect Illumination (GI) Tab Turn it on but don’t change anything just yet, leave it at the default settings and render again.

As you can see the render time has increased dramatically, with 4 prepass stages and then the final render. In these stages the GI is being calculated in progressively more accurate passes.

There is immediately more life in the scene and notice the very soft shadow to the right of the apple, this is being cast by the extra photons coming from the box light on the upper left. Of course these default settings take too long for test renders so we will check out some of the settings in the GI tab.

The GI options should look like this…

Note that the Primary and Secondary Bounces Boxes have an option of which Gi algorithm you wish to use to calculate those bounces, leave these as they are for now, Basically the…

Irradiance Map

Is a fairly good all round and very smooth GI engine, it calculates by taking actual  light samples and interpolating probable photon points in between, this allows for very smooth renders with next to no noise even at lower settings but especially at lower settings it is very poor at capturing small details. You will see this especially on detailed objects where two faces come into contact, it manifests itself as dark splotches and blurry artifacts.

Examples of Irradiance map artifacts on My Ninja Model

Notice the clean gaps between objects

Notice the rather ugly splotches and unclean gaps.

Well those are the basics of the Primary Bounce Engine, the Secondary Bounce is by default calculated by the.,…

 QMC (Quasi Monte Carlo)

This method of calculating GI is much more precise than Irradiance maps and allows  the capturing of smaller details, Rather than interpolating between samples taken it calculates the photon bounces directly, if used on its own however it can cause a lot of noise at lower settings as the detail is directly dependant on the amount of photon calculations made. However it is very useful in conjunction with the irradiance map as they complement each other weaknesses and make for a fairly fast setup.

I will not go into detail about the other GI methods, Photon Map and Light Cache as I know too little about them at this stage, I might do another tutorial later outlining the use of these methods, depending on if this tutorial is well received, e.g.. hopefully  I don’t confuse the last bit of understanding out of people with my endless rambling…lol

 

The main area of control for this Map can be completely mind boggling at first as there are no fewer than 20 different options to tinker with each having a specific result on both render times and quality, I will not try to explain them all because A) I don’t know for sure what some of them do and I don’t want to give out wrong info and B) since this is a basic enough tutorial I will not go into too much detail. I suggest just sitting down for an afternoon and twiddling with the settings until you get what effect they all have.

    

1. The First Thing you should do to optimize the settings is change the Current Preset to Custom, Now we can change the Min/Max Rate options.

Lets simplify this rather complicated method of calculation,

The number of difference between the min and max rate is the number of prepasses that are calculated, e.g., the high preset is from -3 to 0 which is 4 prepass calculations, the higher the number of either the min/max rate is the accuracy of that particular pass, so a
-5 pass is one with very few samples while a 0 is one with very many samples.

Hope that made some kinda sense…lol…but basically its not that hard to understand.
I personally like having 3 prepasses for my renders which range from a Min of -4 to a max of -2. This is good for testing with a nice amount of quality. For final renders a -3 to -0 is excellent and will get very accurate sample rates.

 

Now with that done your Irradiance Map Rollout should look like this. Make sure to check Show Calc. Phase, with this you can watch as the prepasses take place.

Ok with this done render again now.

The results are not all too different to the last render but the render time has been cut in half, this is very good to work with now, giving you fast feedback on all your material and lighting changes.

That render is now ok to look at but in fairness the lighting is pretty poor, the apple seems to be lit too strongly from all sides and completely washed out where the main light hits it, lets see what we can do here.

The lighting is way too strong at the moment, the GI is effectively washing the image out with bright white light so we need to attenuate the Vray light as the main light by turning down the GI.

and you will get

There that’s much better, BUT, the shadow of the apple is showing some nasty noise, there are two ways of solving this, as the Vray light is currently being calculated separately to Irradiance map changing the Irradiance settings will not get rid of the noise. But if you look at the Vraylight settings you will see spinner for subdivisions, increasing this from 8 to 16 will give you this result

The noise is reduced considerably but is still evident, also notice that the render time have increased somewhat, this may not be significant at this stage but when the render is taking hours this kind of increase could be unacceptable.

Thankfully there are always multiple ways of overcoming a problem and by clicking the Store with Irradiance Map option we effectively add the light to the environment as a light source and can therefore control the accuracy of its light together with the GI. Lets see what this does for the noise reduction and render times.

Voila!...nice clean Irradiance Style lighting at half the render time, but because we are working with the same Irradiance settings for the GI and the Vray light the Image has been darkened, to correct this simply Increase the Vray light multiplier, a setting of 8.5  got me back to almost the same illumination amount.

You’ll also notice the slight increase in render time, this is due to the extra photons being shot into the scene to increase the overall light output.

Ok Now that we have a good lighting setup and I think you’ll agree it looks pretty nice already, we can finally start on the materials.

Materials (Glass glass and more glass)

The main Glass Shader.

Three things to remember when making glass,

 

 

Apple Glass

Now, lets make the apple glass shader first. Before you do anything make sure that Vray is also assigned to the Material Editor in the Render Tab under Assign Render. With that done open the material editor and call up a new map.

 

 

Main problem here is that it has no reflections so lets sort that…

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