I'm wondering about the suggested use of the rayswitch node for this. Especially Matt and Ahmidou suggested it. Do you mean the mip_rayswitch_advanced? And would I use it to split up the shader influences on one sphere instead of making the two spheres as in Matt's suggestion?
Because in your 'old school' method, Matt, which I have been using to light the scene and create a background, with an hdri and a higher res color image (seen), there is not the desired glow effect. But it could create light for the FG, instead of a point light, which may be desirable. Any clearer explanations about using the rayswitch node, in this context? Many thanks, Nancy On Jul 3, 2013, at 9:46 PM, Matt Lind <ml...@carbinestudios.com> wrote: > Many solutions, but here's an older simple solution: > > The object emitting illumination should have secondary rays active, and > primary rays inactive. This allows rays to be cast for Global illumination, > final gathering, etc..., but not be directly visible by the camera. This > allows you to use a constant shaded sphere as the emitter. > > The object acting as the bulb and visible to the camera should have the > opposite settings so it appears in the render, but doesn't block the rays > cast by the emitter. > > You may need to do more subtle tweaking of visibility to account of other > situations. For those cases I'll refer you to the 'ray switch' node which > can perform the same task at a more granular level. > > Matt > > > > -----Original Message----- > From: softimage-boun...@listproc.autodesk.com > [mailto:softimage-boun...@listproc.autodesk.com] On Behalf Of Nancy Jacobs > Sent: Wednesday, July 03, 2013 3:02 PM > To: Softimage Listserve > Subject: Requesting advice about light object > > Hello, > > I've been away from XSi for about two years due to illness, but am back > working on a project. So, this may be very easy for you guys to answer. I'm > feeling noobness here, having forgotten so many things! > > I'm trying to make a small sphere look like a light source, illuminating part > of the scene, which is only lit by final gathering and a globe HDR object. > I'm pretty sure I've done this successfully before, but it's failing me this > time...;-) > > I can't make the sphere a constant material, because I want it to use many of > the attributes of the architectural shader. In other words, I want it to be a > reflective ball which is glowing and emitting light. I like the simplified > emulated reflections i was getting by using optimizations in the > architectural shader (also the rendering time advantage). So, I tried putting > a point light inside it, which has somewhat fouled up the nice surface I had > going with the architectural shader. And there is no 'incandescence' in this > shader to make it appear glowing. I don't want to see the actual point light > in the render, but I do want the ball itself to be a bit luminous. > > I'm also having a lot of trouble with the light attenuation using the > exponent. Does anyone have any idea how to measure 'Softimage units' in ones > scene? Do they relate to say, the sphere radius I am using? Or is that a > whole 'nother thing.... > > Anyone who can give me some ideas or point me to some info about this glowing > sphere light thing, much appreciated... Seems so rudimentary... > > Thanks, > Nancy >
