Travelling Sheens and Logo Treatments


Yesterday I had a customer request (specifically) that I give his flying logo this treatment, after it has come to rest in the scene. Could I have a couple of suggestions how to best achieve this effect?

Hi Jim,
First make a reflection map for the logo face.This map should be white diagonal streaks over a black background. I used approximately 5 streaks. Save this image and use it as a reflection map for the surface of your logo. Parent the camera to the logo and rotate the logo around. This will cause the surface to reflect different parts of the image map and it will appear as if light is moving across the screen. I learned this technique from p.24 of the January 1994 VTU Dear John section that John Gross wrote and it works perfectly. He also recommends turning on Color Highlights for a high degree of reflection.

Lorenzo
LVH Productions

One of several possibilities:

Use the Grid Texture on Luminosity to create a narrow vertical glint (or sheen) on the logo face surface.

To get a narrow vertical glint:

Set the Texture Falloff to a rather high value in the X axis, (200%, for example, to get a 1 meter wide glint, assuming a 100% Texture Value.)

World Coords must be ON.

Texture Size is irrelevant.

Texture Value should be at least 100%, or more for a brighter glint.

Line Thickness must be 1.0.

Then parent everything in the scene to a new null object; camera, lights, objects... everything.

Bank the null to obtain the glint angle desired, and move the null off along the X axis so that the glint is beyond the end of the logo.

When the time comes for the glint to travel across the logo, move the null along the X axis, and the glint, tied to the world coords, will pass over the logo, sheen-like. (Actually the logo passes over the glint, but who's counting. :)

The thing I like about this method is that you have more immediate control over the width, brightness, angle, etc. of the glint than by using lights, or using a reflection map or other image that would require repainting to change these attributes.

Also, unlike an image, Grid doesn't get blocky pixel disease.

James G. Jones

What do you mean by "used a clip-map image sequence to make..." How is this sequence made to make the objet disappear except for the highlight?

I guess this is where I should explain the technique more thoroughly than in the message I sent to Dennis way back when...

* In Modeler, copy the face polygons from your logo and paste them to a different layer. Change the surface name for these polygons to something like "LogoSheen". Save this layer as "LogoSheen.lwo"

* In Layout, load your normal logo object and load the "LogoSheen.lwo" object. Parent the "LogoSheen.lwo" object to the logo object and offset it's position a little so that it is "in front" of the logo.

* Set the surface values for "LogoSheen" surface to something much brighter than the normal logo object's face polygons. Use a Luminosity that is greater than 100%.

* For those of you WITHOUT AMIGAS, here comes the tough part...use a paint program (like DPaint) to create a grey-scale image sequence of the actaul sheen moving across the screen. You should start with a solid black (or solid white) screen and have a bright white (or dark black) angled "bar" brush move across the screen the same way you want your sheen to move...this can be done in a few minutes with the Anim/Move Brush function. The goal is to create an image sequence that will be used as a clip map in LightWave.

* Load your image sequence into LightWave.

* Apply this image sequence as a Planar Image Map clip map to the "LogoSheen.lwo" object. If the image sequence is black with a white sheen, then you will have to turn on Negative Image. (Be sure to turn off Antialiasing and Pixel Blend)

And that's pretty much it...when you render the animation, the "LogoSheen.lwo" object will be invisible until the clip map image sequence sheen makes only certain parts show up. You can get some really nice effects by changing what the clip map looks like...try using jagged or round shapes instead of a straight line. The best thing about this technique is that it renders very quickly and you can get a clear idea of what it will look like before rendering...especially now with OpenGL support in LW 5.0!

-David Warner

 

© 1998 Primordial Soup Animation