View Full Version : making lights reflect?

07-22-2004, 09:49 AM
Hi! I'm working on a scene where I'm augmenting some live footage of a 'death machine' and am having surface problems.

I'm trying to add an evil circular saw attached to a metallic arm sprouting from the back of a live action chair-like thing.

Right now all the objects share the same surface-- a shiny metal-- and I've added the original footage as a spherical environment for reflections.

My problem is that although I think the arm parts look pretty good, the circular saw is not reflecting properly. As you can see from the screenshot, I'm trying to match some bright toplighting. The saw, however, when pointed up, doesn't catch the lights.

My first question is-- do lights reflect on surfaces in lightwave? I've got a point light at the top of frame cranked to 200% or something. The lighting seems to reflect well in quickshade mode, but in realistic mode the 'glare' disappears.

I'm a little bit of a newbie when it comes to surfaces, and I've read some stuff in these boards about creating reflections with incident angles in the surface, etc... but for this scene I need the objects to reflect the lights at the top of the scene geographically... not in relation to camera angle. At least that's what I think I need.

Thanks so much for helping a noob out!!

07-22-2004, 12:42 PM
Add a small reflection to the blade sides to help with the Circular illusion that a saw blade has when it spins also turn on Raytrace Refrections in the Rendering Options. Also you need to add specular to the blade so it will pick up the the light in the scene.

07-22-2004, 02:38 PM
Thanks a ton for your reply, wizcraker.

That definitely helped a lot. While I had had the specularity high, I cranked it above 100% to get the results I wanted.

Then, however, I experimented around with the image seam angle of my environment. You may recall that I was using the original footage to reflect as an enviroment spherical map. I found with some tweaking I could position it so the highlights seemed to appear at the right time. I could then lower the specularity, as highlights were showing up in my objects. I even got some pink from my damsel's dress to reflect (see second screenshot).

Follow up questions are: 1) I had to kinda guess around via trial and error to find the right image seam angle for my environment to reflect correctly. Is there a method to lining up environments?
2) I think a problem I was facing at the outset was that my environment reflects really BIG. That's why I wasn't seeing reflections in my first go... the dark blue of the frame was reflecting... and not the highlighted areas. Is it possible to shrink the size of the reflections? The environment reflects nicely in the 'arms' of the saw thing because they wrap around. But in the flat saw blade I need to be precise or risk reflecting the dark/uninteresting portions of the environment footage.

Thanks for all thoughts on this subject! Any other ideas on making reflections look real to match real footage would be appreciated!

07-22-2004, 02:39 PM
here's the first frame with proper highlights.

Triple G
07-22-2004, 09:58 PM
When I need to do stuff like this, I usually map the image to a globe with its normals inverted. Make the surface 100% luminous, and turn everything else down to 0. Turn off shadows for the object in layout, and make it unseen by camera (but SEEN by rays!) This way, you can scale/move/rotate the globe to position things much more easily than if you use an image probe or texture environment.

07-22-2004, 10:37 PM
Thanks for a great tip, Gregg. I'll give it a try!

07-23-2004, 12:06 AM
looks cool!
I suggest you blur and tweak video distortions to match the background!