Artlantis 4.0 Radiosity This tutorial covers the radiosity parameters found in Artlantis 3.
We will focus on each setting, analyzing their effects on the rendering quality and light conditions. First, activate the proper checkbox in the Preferences menu to access all the extended parameters. The radiosity parameters have two main sub-sets.
I. Radiosity expert parameters
 |
1. Accuracy Defines the precision of the radiosity calculation.
There is a scroll-down menu that has three pre-defined settings : normal, medium and high.
Long range slider : defines the distance (in pixels) between the radiosity sampling points on the image being calculated.
The area between the radiosity sampling points are interpolated. The shorter the range the higher the radiosity quality achieved. Values from 96 to 8, lower value means more samples to calculate.
Short range slider : works similarly to the previous one, but this one defines the special processing for nearby surfaces. The longer the range analyzed for this type of process, the higher the radiosity quality achieved. Values from 0 to 48, higher value means more samples to calculate.
2. Lighting
Lighting defines the lighting conditions. Pre-defined settings for interior or exterior light conditions can be activated from the scroll down menu.
Before we continue, a short explanation is needed here about how radiosity works.
In real life, emitters emit photons. Popping from object to object, they light our world while losing their energy as they are partially absorbed by surfaces.
|
|
|
1. First bounce controls the tone of the bounces that effects the surfaces receiving direct light.
A higher value means a larger contrast between the light and shadows.
2. Next bounces controls the power of the bounces after the first bounce. More bounce produces more energy on the surfaces; a higher value means more light on surfaces that receive indirect light.
|
3. Attenuation defines the amount of absorption of the ”energy.” 1.00 means that the energy is kept while bouncing toward, while 0.50 means energy is halved for each bounce. It affects the contrast of the radiosity shadows.
4. Color bleeding controls the amount of color transferred from surface to surface. Low valuedesaturates the radiosity calculation.
|
II. Radiosity parameters - Accuracy
1st render
Accuracy is set to normal
Assessment : A rough picture. Draft shadow/light conditions can be checked easily on larger surfaces; smaller surfaces have a general ambience and lack of precise details. This rendering setting is ideal for quick test renders.
Explanation : let's focus on the normal, pre-defined setting regarding the accuracy sliders.
Long range : 96
Short range : 4
These two values mean that radiosity is computed using only a low number of sample points, while large sections of the surfaces and the image are simply interpolated. Therefore, the radiosity is not very precise. |
|
2nd render
Accuracy is set to medium
Assassment : Better radiosity quality, owing to the larger density of sampling points. On small surfaces, such as parts of toy cars, we may observe better shadows and less general ambience.
Radiosity shadows around the objects become visible.
Explanation : the medium, pre defined setting has the following values :
Long range : 64
Short range : 16
Value 64 of “long range” occurs in more precise radiosity calculations. Value 16 of “short range” affects the surfaces nearby, emphasizing details and creating radiosity-shadow transitions. |
|
3rd render
Accuracy is set to high
Assessment : High radiosity quality with precise and soft shadow transitions. Comparing the image to the
previous render, we may observe smaller details. Radiosity shadows are soft and have less contrast.
This setting is highly recommended for final renderings.
Explanation : the high pre defined setting has the following values:
Long range : 32
Short range : 32
Density of radiosity sampling points is enough to produce this result.
It is important to mention here that the higher quality we choose the longer the render takes. |
|
III. Lighting conditions - Bounces and Attenuation 
1st render Accuracy is set to high, Bounces: 4-1
The picture is O.K. Lack of enough secondary bounces; surfaces that receive only indirect lighting stay dark. The contrast between shadow and light is too much. Lets tweak the “Next bounces” slider a bit. |
|
2nd render Accuracy is set to high, Bounces: 4-4
Surfaces in shadow got brighter in general. More secondary bounces provide more lighting power calculated onto these parts of the scene |
|
3rd render Accuracy is set to high, Bounces: 4-8
Surfaces got brighter again a bit. Comparing to the previously calculated images, it is obvious that surfaces facing downward (such as the bottom side of the roof and slabs) got brighter.
More and more small details can be seen in the shadows. |
Attenuation has an affect on the calculation as well as on surface brightness.
Low bounces value can be compared with higher Attenuation value. On the other hand, if the surfaces are too bright because of high secondary bounces; decreasing the Attenuation value will solve this.
|
It is important to note that calculating more bounces takes more time to render. It is quite important to see clearly how each rendering parameter works and what their effects are.
What is more important is finding the setting that provides the requested quality and worth to render regarding the rendering time. |
|
|
|
|
|
