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Atmospheres Underwater

For use with Poser 7 as well as Poser 5 or 6

Poser 6's new lighting models (point lights, image-based lighting, ambient occlusion) provide a great deal of realism in many situations- but in this tutorial we'll use an older lighting trick to explore new depths of realism, by simulating underwater effects.

A little-used feature of Poser's lighting is its ability to simulate atmospheric effects- fog, smoke, etc. Applying an atmosphere is not difficult but its effect is dependent on scene features and light settings that aren't immediately apparent. Specifically, in order for atmosphere effects to show up in the rendered image, two things need to happen-

(1) There needs to be a background against which the atmosphere will appear. This can be any combination of props and figures, but atmospheric lighting only shows up against a solid object.

(2) The lights in the scene must be set to use the atmosphere. By default, lights are set to apply the atmosphere at 1%, or 0.01; turning the atmosphere strength up enhances the effect but you need to be careful not to overwhelm the scene with the atmosphere.

For underwater scenes we'll use the Depth Cue and Volume settings on the Atmosphere; we'll also need to apply some shaders to the lights in the scene to simulate the way that light bends water. Poser doesn't have any way of creating caustic effects, in which transparent surfaces (like water) bend light to focus or diffuse it (for an example of caustics, see ), but underwater caustic effects can be faked by applying procedural shaders to the lights themselves.

1. Set Up The Scene

You can use whatever props and figures you have available- Poser ships with a dolphin and an angelfish in its default libraries, and there are a great many aquatic figures available through sites like our own . For this tutorial I used the default Angelfish as well as the CP Stingray and Manatee figures. We'll need to use the Single-Sided Square prop as the backdrop for the scene- move it back -20 along the Z-axis with the ZTranslate dial and scale it to fill the camera view. Apply a blue color to the square (using the paint bucket, or in the Material Room) to simulate water.

2. Apply the Special Effects

After setting up the figures and props- remember the backdrop!- it's time to apply the atmosphere. To do this we click the Material tab to go to the Material Room. We'll need to use the Advanced Material Room, so click the Advanced tab if necessary; choose the Atmosphere from the Object menu. To simulate water's light-scattering and dimming effects, check the Depth Cue and Volume boxes, and set the colors (in the Volume and Depth Cue channels) to blue.

Just to add a fancy effect, drag the little plug icon off to the right of the Color channel and choose New Node>3D Texture>Cellular to attach a Cellular node; adjust the scale of the effect along X, Y and Z as shown-

Now that the Atmosphere has been set up, and as long as we're in the Material Room, let's fix up the lights. Since we're simulating an underwater scene, the lights should be set to blue or blue-green- we can do this by choosing a light in the Object menu and changing its Color value. We'll also want to attach a node to each light to simulate the caustic effect of light in water- this is easily done with another Cellular node. Attach one to each light as shown here-

3. Get Ready To Render!

With the lights set up and the atmosphere in place, we can go back to the Pose Room and make our final adjustments before rendering the scene. In particular we want to make sure that our lights are shining down from the top of the scene, since the water isn't generally lit from below, and it might be a good idea to turn the atmosphere effect up just a bit on the main light in the scene. Depending on the precise effect you want it might be necessary to do a couple of test renders to see which settings give the perfect effect.

That brings us to the point of actually rendering. Atmosphere effects don't require ray-tracing, but rendering with atmosphere effects does add considerably to the render time, so test renders should either be small or should be done as area renders, to save time and frustration.

The results, though are worth the wait-