Cineversity

I might very well be missing something here but I thought I’d ask the community to see if someone’s seen this.

I have a scene where I put in a point light specifically to catch specular on some text - so I disable diffuse lighting for that light.  However, in this particular result the reflection of the text shows the results of diffuse lighting for the side of the object that would have received that lighting if I had it enabled.  Basically it appears that disabling diffuse lighting for a light isn’t considered for object reflections?  Is there another way I’m doing this that I’m missing?  See the attached image - you can see the lighting on the right side of the logo and the reflection of that same side is lighted completely differently…  Bug, perhaps?

I think what you are seeing is correct.
What you may be getting is that spec light also casting a spec onto your reflective material that is causing the reflections of the letters to appear lighter.

When you disable the spec. light are the reflections darker.
What about if you turn off the specular channel on the reflective material (if it’s not off already.)

I rebuilt a file myself to see if I could confirm but found no issue.

Hey Newtmich,

There are several ways to have more control about those things. A typical use for ExtrudeNURBS objects is the C1, C2, R1 and R2 preselections for the Caps and Roundings. (The other parts need to have the material on the left in the Object manager. In this way you can set up for the specific parts of the Extrude NURBS more or less (none) specular.

The other way is given with Multi-pass and Object buffer, In that way you might dial in the effect “in Post” and get it done perhaps faster and easier to change, if someone like to have the specular highlights e.g. brighter, colder etc.

More simple, but longer rendering, one render pass without the light that cast the spec and one rendering pass with it, then blend as you like.

The Multi-pass set to “all lights” is certainly the way to go to find out if there is a light in the scene that works against your target. It’s in an upcoming series of mine a tip.

All the best

Sassi

P.S. I can’t reproduce it here, e.g. set the Material spec color to blue in a new white material, to check if you get anything else than blue while the diffuse is off in the light

Patrick Goski - 10 May 2012 02:15 PM

I think what you are seeing is correct.
What you may be getting is that spec light also casting a spec onto your reflective material that is causing the reflections of the letters to appear lighter.

When you disable the spec. light are the reflections darker.
What about if you turn off the specular channel on the reflective material (if it’s not off already.)

I rebuilt a file myself to see if I could confirm but found no issue.

Thanks Patrick.  The reflective material has no spec - I opted for a “true specular highlight” via reflection so I disabled spec in the first place.  I turned the diffuse of the light back for the light on and didn’t see any change in the reflected side of the extruded text - not sure if that tells us anything or not.  I’ll take a look at your file and see what I can see from there.

Dr.Sassi - 10 May 2012 02:32 PM

Hey Newtmich,

There are several ways to have more control about those things. A typical use for ExtrudeNURBS objects is the C1, C2, R1 and R2 preselections for the Caps and Roundings. (The other parts need to have the material on the left in the Object manager. In this way you can set up for the specific parts of the Extrude NURBS more or less (none) specular.

The other way is given with Multi-pass and Object buffer, In that way you might dial in the effect “in Post” and get it done perhaps faster and easier to change, if someone like to have the specular highlights e.g. brighter, colder etc.

More simple, but longer rendering, one render pass without the light that cast the spec and one rendering pass with it, then blend as you like.

The Multi-pass set to “all lights” is certainly the way to go to find out if there is a light in the scene that works against your target. It’s in an upcoming series of mine a tip.

All the best

Sassi

P.S. I can’t reproduce it here, e.g. set the Material spec color to blue in a new white material, to check if you get anything else than blue while the diffuse is off in the light

Thanks Dr - a few things to try.  I’ll give them a try when I have a minute this evening.  I prefer avoiding the multi-pass if I can help it although it would allow me to dial in the highlights on the main object exactly as I wanted.  I mostly wanted to confirm whether or not I was seeing an aberration of rendering somehow.  I’ll try a few more things and post here with the results.  Thanks again!

Hey Newtmitch,

You’re welcome. There are two ways, one is just to render a single frame as Multipass, not even saving is needed, to get for each light a separate rendering in the picture viewer, this allows very fast to see what each light does to the scene. Sometimes those effects as you described them are based on the fact that a scene has already lots of lights, like one case I got where a light was on a layer, but hidden—except for the rendering. So I stay open to all sources of such “effects”.

Have good one

Sassi