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LW²TG Documentation

 

 

 

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LW²TG Tutorials
Basic Setup & Camera Matching
  Adding LightWave Objects to the Scene
  Casting Shadows from LightWave Objects onto the Terrain
  Animating with Motion Blur
  Matching a Terragen Scene in Layout
 

 

Casting Shadows

Since the terrain models are currently set up with a totally luminous surface, shadows will not be cast on them so go to the 'Surface Editor' and set the 'Luminosity' back to 0% and the 'Diffuse' back to 100%.

There are two methods of adding shadows depending on which version of the plugins you are using or how much control over the final render you need.

The first method uses LW²TG_ShadowComp from the full version of the plugins. This enables all shadow rendering to be done entirely within LightWave.

The second method involves rendering out different elements of your scene and then combining them together in an external package such as Photoshop or After Effects. Depending on the scene this method can give more flexibility and control over the final animation at the expense of longer setup and render times.

A useful alternative is to combine the two methods by using LW²TG_ShadowComp while you are creating your scene and generating test renders (enabling you to quickly see where the shadows from your objects are falling) and then rendering the final animation as seperate passes for compositing when the shot has been finalised.

Both methods are described below.

 

Using LW²TG ShadowComp

(Full Version only)

Open the 'Effects' panel and select the 'Processing' tab.

Select LW²TG_ShadowComp from the 'Add Pixel Filter' list.

Open the 'Surface Editor' and select the terrain surface.

Click on the 'Shaders' tab and select LW²TG_FPM from the 'Add Shader' list.

LW²TG_FPM automatically assigns the background image sequence to the terrain surface, there are no other settings required.

Click on the 'Advanced' tab and then on the 'Special Buffers' button. Enter a value of 255 in the 'Special Buffer1' field.

Any LightWave object that is placed in the scene will now automatically cast shadows onto the terrain. The strength and colour of the shadows can be adjusted by opening the options dialog for the plugin.

 
You can now move the camera anywhere in the scene and the shadows from your LightWave objects will automatically be added to the Terragen terrain.
 

Rendering as Separate Passes

(Demo Version)

Open the 'Surface Editor' and select the terrain surface.

Go to the 'Advanced' tab and select 'Shadow Density' from the 'Alpha Channel' list, close the 'Surface Editor'.

So that the objects don't show up in the alpha channel we need to set the 'Alpha Channel' to 'Constant Value' and the 'Alpha Value' to 0 for every surface apart from the terrain. This will leave us with an alpha channel containing only the shadow areas as below.

Remember to select 'Save Alpha' in the 'Render Options' panel.

Render the frame. Two images will be saved out, one for the RGB and one for the alpha channel.

You now need to combine the two rendered images in a paint package that supports layers (Photoshop or Paint Shop Pro 5/6 for example).

Load up the two images, copy and paste the alpha channel image onto the rendered image as a new layer. Invert (Negative) the colours of the layer so that the shadows are black. Set the layer combine mode to Multiply. You will now see the shadows on the terrain as shown below.

As it stands these shadows look too dark and too sharp, set the layer transparency to around 40 - 50% and apply a small amount of Gaussian blur to the shadow layer.

TIP: You can also use your compositing package to tint the colour of the shadows allowing an even closer match with the Terragen renders.

There are other methods of achieving the effect of Lightwave objects interacting with and casting shadows onto the Terragen renders but I find this method gives the most flexibility when it comes to adjusting the shadows. The process sounds long and tedious when written down like this but you'll find it only takes a few minutes to do once you've generated a few images.

 

 

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