WorldBuilder 4 Basics – Part 4

Let’s start by reviewing our scene in Production Rendering mode (once you’ve rendered the scene, click on Incremental Design Step Forward).

All of our landscape, vegetation and water elements are satisfactory.

But there is still something missing: an element of scale and distance. In the real world, airborne dust and haze cause distant objects to appear lighter and ‘washed out’ (this is sometimes called atmospheric perspective). We will now duplicate this visual phenomenon by applying a filter to our scene.

In the Scene Tree, select Scene and in the Properties Tree right -click on its Filters node.

Select the Haze filter. A little bit later we will add the Volumetric Light filter, as well.

Note: The Fog and Two Color Fog filters could also be used; they are both filters that were created for earlier versions of WorldBuilder.

After the Haze filter appears in the Properties of the Scene, re-render the image. Since we’re working with Incremental Design, the filtered image will appear very quickly.

The image is bleached out and is too foggy. We have to adjust the Haze parameters in order to simulate the conditions of a sunny day.

The Haze filter simulates light scattered in the atmosphere. Since the blue component scatters more, the color of the sky is blue; distant objects have a blue tint in a clear atmosphere. We can describe how the air scatters the light by specifying the distance at which the light intensity will be reduced to half of its original value. With independent Half Transparency Distance for each of the color components, you can set scattering of the blue component to a higher value (shorter Half Transparency Distance) to produce more realistic results.

We need to ‘push’ the Haze away from the Camera.

Let’s increase the Half Transparency Distance for all 3 color channels by a factor of 4.

Knowing the size of the Landscape object (1000 meters on a side) helps us to pick a good first approximation for these parameters.

Let’s re-render the scene again.

Although we are getting closer to a light haze on a sunny day, we lost some of the contrast and bright colors of the original image.

We can compensate for this by applying the RGB Levels filter. It works in a similar manner to Photoshop’s Autolevels filter.

In the Object Tree select Scene again. Right-click on Filters and select Add. Select RGB Levels.

Here is the image with both the Haze and RGB Levels applied.

Now the colors are over-saturated and the contrast is too high.

To reduce this effect, let us change the target colors’ range to make it closer to the original range in the window grayed out above.

Let’s use a target range between the full 0 -to- 255 values and the original range.

So instead of 0 for min Red, let’s enter 50.

Let’s increase the min Green Target value to 12.

We could play with upper limits as well, but these settings will produce a good result.

Let’s render the image again.

Overall, the newly-rendered image is closer to the original in terms of its foreground (we’ve ‘warmed up’ the colors somewhat), but the forest in the background still retains its hazy appearance.

In the Property Tree, right-click on Filters.

Select Disable all.

Right-click again on Filters and pull down to Add.

Select Volumetric Light from the Atmosphere/Volumetric group and click OK.

Because we’ll need to move the Light source (to use the Volumetrics filter to better effect), the look of the entire scene will change.

Select the appropriate Light source. Move the light source away so that it will shine almost directly into the Camera. Make sure that the Light’s Targeted parameter is enabled.

We need the light source to be visible in the Camera window. Placing the light source’s Target near or just behind the camera makes it a little easier to position and ‘aim’ the camera.

You’ll also need to make sure that the light source’s Shadow map is enabled. Use the Shadow View in Current Viewport feature to fine-tune your light placement.

Try to place your light so that Aspen 1 is between the light and your camera.

Because we want to simplify our lighting effect, open CompoundSky (in the Scene Tree) and delete the SunDiskWithHalo layer.

The idea behind all of this is that we want to create beams of light. Usually these become visible at the edge of a bright light and a shadow with fringed edges, like that cast by a tree or a cloud.

Once we have got our light source placed, let’s render the scene.

The default settings for Volumetric Light produce an interesting ‘flare’ effect, but we aren’t yet seeing the light beams that we want.

NOTE: You may find that the Volumetric filter produces a more effective render without Incremental Design.

Let’s examine the Properties Page for the Volumetric Light filter.

The Samples and Mask Size variables control the quality of the rendered Volumetric effect.

Let’s lower the Samples setting to 40.
This will reduce the number of volumetric ‘evaluations’ performed along the camera’s longitudinal (view) axis.

Now let’s increase Mask Size from 3×3 to 4×4.
This will allow the filter to interpolate the Volumetric effect across every 4th pixel in our image; the filter’s effect will be calculated more quickly, but it will also create a softer shadow until we use a finer setting (2×2, for example) with the parameter.

When we re-render the scene, we can see the light beams ‘streaming’ away from the light source and toward the camera.

Let’s adjust the Brightness settings.

Set Direct and Scattered Brightness to 2.
This will increase the overall opacity and contrast of the light beams.

Set Direct Glow Brightness to 1.
This will increase the intensity of the ‘flare’ behind the tree.

Set Direct Glow Radius to 0.1.
This will shrink the flare so that it has the appearance of emanating from a distant, bright source.

Let’s re-render the scene again.

We’re starting to get the effect we’re after, but our light beams are still lacking definition. Also, the overall effect needs to be heightened a little more.

Let’s apply the original Samples variable of 80, increase the Mask Size to 2×2, and set the Clipping Distance to 200.

Our scene is looking pretty good.

Let’s make another set of adjustments.

For Direct Color, select yellow.
For Scattered Color, choose a cooler bluish hue.

Our Volumetric effect now has a little color!

Let’s increase the Samples parameter again, this time to 160.

Adjust Mask Size to its finest setting: 1×1.
The Volumetric effect will now be applied to every pixel in the image.

Before we re-render, let’s enable the two other filters we applied earlier.

In the Property Tree, right-click on the Haze and RGB Levels filters and ‘un-check’ Disable.

Note: RGB Levels is a ‘post-process’ filter, which means it’s applied to the scene after it’s been rendered. In order to do this, it needs to be the ‘last’ filter in the Scene’s Property Tree. Currently, it is situated between Haze and the Volumetric Light filter. We need to ‘move’ it to the bottom of the Property Tree.

We could delete the filter and re-add it, but we’d lose its settings.

We can, however, use the Properties Toolbar to Copy the RGB Level settings.

Then we can delete the current filter and Paste the settings, once it’s been re-added.

Let’s re-render the image once again.

During this part of our tutorial, we have:

• reproduced the effect of atmospheric perspective by applying the Haze filter
• compensated for a slight loss of color saturation by using the RGB Levels filter
• created light beams by using the Volumetric Light filter
• moved the RGB Levels filter (so that it appears ‘last’ in the Property Tree) by using the Properties Toolbar to Copy and Paste its settings