Hello agin. I
hope you saved the resulting scene and objects from the Speaker tutorial as we will continue
from there. In this tutorial we will modify the scene and make the
speaker and the blob objects seamlessly integrate into a background
photograph.
So, load the scene you made in the Speaker tutorial and then open the image editor. For conveinience's sake i decided to use MountainHighway.iff as the background - you can locate it from Images/Landscape folder in your Lightwave install directory. Load the image. If you can't find it, you can always get it from the Lightwave installation CD. Next go to the Scene > Backdrop > Compositing tab and and set MountainHighway.iff as the BG image. The BG image is always on "top" of other backdrop types, so you don't have to remove the SkyGen environment. |
Okay, what we
have so far should look something like this. Notice how the ground
surface smoothly blends to the background image because of the backdrop
fog.
Also, notice how the background image is severely distorted. Let's fix that now. go to Camera properties panel, and set the render resolution to 640*427, which is the resolution of the mountain highway image. Next thing
to do is to modify the ground surface to show the background image
through. Go
to surfaces panel and locate the ground surface. Open the color texture [T], and modify it to
the following settings: |
Projection: Front - this will cause the surface to always get it's colors from the selected (usually background) image. The surface will always be perfectly aligned to the camera (I will later refer to this mapping method as FP mapping).  Believe it or not, but
the result looks much better than what i would have wanted - i was
about to demonstrate the most common problem with FP mapping, the
visible polygon edges caused by lighting/shading the FP objects. In
this case the lighting in the scene causes rather correct luminance
levels to the ground object, and when the backdrop fog blends the
ground object to the background image smoothly, there are no visible
artifacts.
Set the fog off. Rotate the Sun_REF object about to Heading 260, Pitch -50, Bank 0. Open the SUN_mixer object's endomorph mixer (Object properties > Deformation), and adjust the sun color sliders to 80% B, 90% G, 100% R. First of all, this will make the lighting match the scene better. Second of all, the errors i mentioned earlier are now visible. Even though the errors still are subtle in this scene they can become extremely annoying with a little more complex geometry - or if the lighting is uneven (see the arrow pointing at the polygon edge - the ground is lighter and of warmer tone than the bg).
|
| |
| Okay, it's
time
to run one more LScript - called OC_Exclude. This script will make a selected object recieve
only shadows from Overcaster lights.
To make the ground object perfectly match the background, set it's surface 100% luminous. Adjusting the shadow catcher object's surface's diffuse amount controls the density of the shadows. In order to separating shadows from the diffuse and specular shading, the Overcaster rigs use negative lights for the shadows. As these negative lights are the only ones that affect the shadow catcher object after running OC Exclude, surface's diffuse level actually becomes shadow density adjustment. I ended up
setting the diffuse level to 50%. On the
left, the new (PlugPak 2.0) version of Overcaster Exclude. Running the
script at default settings equals PlugPak 1.0 performance. |
| |
| Okay... i
think
we are done for now - here's the finished render.
|
Let's
start by
loading our backdrop image. 
Well - let's
make some! 
Set
the ground
object the shadow catcher object. Notice that the ground object will become
black after running the script, because the script has disabled
overcaster lighting from the selected object. 