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DHudson
05-13-2008, 03:38 PM
Hello-

I am trying to render a peice of wood moulding- it is PVC covered- so it is white. It is supposed to be very shiny and reflective. But - it sits in the scene by itself and has nothing to reflect.

I think instead of white - i have to make the color a light gray to show shine- is that true? And how do I show a reflection of something on it with nothing to reflect? I tried putting a reflective image in the light- but then lost the shine.

help please :(

4dartist
05-13-2008, 04:04 PM
There are a lot of ways. The main goal is to give the object something to reflect.

1st way> What I usually do is make really big sphere and make the polygons face inside. Then I wrap some image on it, like a sky or panoramic setting. Put the sphere in layout and have it really big so it surrounds everything by a lot. (don't make it TOO big or it's just anoying to work with) Then select the sphere, go to object properties, turn off cast/receive/self shadows and set it to 100-luminosity 0-diffuse. Last, make it unseen by camera. (now it will reflect, but not render the actual backdrop)

You can use a sky, or outside setting, or just a reflection map like the ones newtek provided online where you download LW.

2nd way> I do that method because you can see the backdrop in the scene and rotate/move it how you want. But instead you can put the image as a background image. To do this hit ctrl-F5 or find the Backdrop settings area. Then click 'Add Environment' and you can use textured environment and wrap it spherically or however you wish. If you want to prevent the image from rendering in the backdrop you can cover it up by using the 'compositing' tab just a few tabs over on the same 'backdrop' window. In the compositing tab just pick background image and select a 1pixel by 1pixel black image that you make in photoshop. Then i'll render a black background instead of the image you are using to reflect.

3rd way> (probably the easiest for simple scenes) select the reflective surface in the 'Surface Editor' and click the 'Environment' tab instead of 'Basic' tab. Then for Reflection Map, you can put in any image and it'll reflect that image + any other objects in the scene.


I'm sure there are more ways, but those I think are pretty common and easy to do. I use #1 all the time, but we have massive scenes with lots of objects reflecting so it's easier than editing each surface at a time.

DHudson
05-13-2008, 04:12 PM
Great! thank you Benjamin.

I am still having trouble with the color itself. All the shadows look washed out. It is a glossy image on a white background. Here are my settings:
Luminosity: 0
Diffuse: 100%
Spec: 100%
Glossiness: 60%
Reflection: 40%
Trans & Transluc: 0
Bump: 100%
Smoothing on

See anything I need to change?

Thanks again so much.

4dartist
05-13-2008, 04:31 PM
I suppose if you have a pretty reflective surface and white is your background color then the area in shadow is still going to be very light because it's reflecting all that white. If you could post an image it would be very helpful to give you better advise. or a scene/model.

Just because the end product is going to be on a white background doesn't mean you have to have the background color be white. If you change the background color from white to lets say gray, or an image using a method mentioned above ^, then you can still composite the object onto a white background. A couple ways to do that.

1. output the image from lightwave as a 32-bit image so it has it's alpha channel with it and then composite in photoshop. (be sure to turn premultiply off in the render global output section)

or

2. like mentioned above use a 1pixel by 1pixel white image and in the compositing tab of lightwave (control-F7) Then you can change background color to blood red, and it'll reflect blood red but still have a white background. (not that you want to use blood red) hehe.

Titus
05-13-2008, 04:34 PM
HDR images are excellent to get reflections.

DHudson
05-13-2008, 04:54 PM
Here is the image I am working on - as you can see- no reflection. The numbers under the Basic tab are still troubling me.

Thanks so much for all the help.

DHudson
05-13-2008, 08:23 PM
Here are the Object file and the Scene file. I tried the large sphere textured and the moulding profile was blown away by "whiteness" lol...

Any suggestions? Thanks!

4dartist
05-14-2008, 12:31 PM
Well the 1st thing i see about the scene, is that you have 'raytrace reflection' turned off. If you want to reflect objects you need to have that turned on.

DHudson
05-14-2008, 12:36 PM
I caught that after I uploaded the file. My bad :( Thanks for catching that

4dartist
05-14-2008, 12:45 PM
--> My files <-- (http://4dartist.com/cgtalk/reflectiontest.zip)

I played with it some and used a reflection map thats free from newtek.

I changed your surface a little. I think reflective objects should have a little less diffuse, because a lot of it's brightness comes from reflecting stuff.

Ben

4dartist
05-14-2008, 12:51 PM
oops i think I forgot to save the object. Re-uploaded files.

SP00
05-16-2008, 07:01 AM
I see that there is an issue with your diffuse and reflection channel. If you want realistic materials. You got to balance out the diffuse and reflection to equal something below 100 percent. This is a general rule, so you don't have to use it all the time.

DHudson
05-16-2008, 07:20 AM
Thank you 4dartist- for working on that - I have version 8 and cannot open it though :(


Thanks for the thought SPOO - its an early lesson I should have remembered

Mike_RB
05-16-2008, 07:43 AM
You have to simulate energy conservation. You can't technically shine back more light than you receive. So anywhere you make reflective you have to lower the diffuse by the same amount.

DHudson
05-16-2008, 07:46 AM
Thank you for your thought Mike ... Lowering the diffuse makes the profile darker - and its is supposed to be white with a shine to it. So what do I "up" to make this not so dark?

SP00
05-18-2008, 10:28 PM
Thank you for your thought Mike ... Lowering the diffuse makes the profile darker - and its is supposed to be white with a shine to it. So what do I "up" to make this not so dark?

So if you use a diffuse 90% white, the reflection shouldn't be more than 10%. In theory, there is no limit to how white a color can get. So by making you color off white, I don't think anyone will complain.