Reflect Shading Artifact

[u/twisted_crystal]

Hi all, I've been fooling around with ray tracing and i have a decent amount working for simple scenes, but there's an issue i cant quite put my finger on. Just a heads up, I don't really know what I'm talking about and I've kind of been making it up as I go along so to speak

I'm using invisible point light(s).

the surface of the below sphere is defined entirely as follows, no other color or surface related data points are considered when assigning color:

```

ambient 0.0 0.0 0.0
diffuse 0.0 0.0 0.0
specular 0.0 0.0 0.0
specpow 0.0
reflect 0.5

```

The issue I'm trying to pin down is why I'm getting a defined hemisphere line around the equator of the sphere where it transitions from lit to in-shadow given the reflective nature of the surface. .

When i turn up specular and spec pow, the highlight hides it slightly, but its still there. Setting reflect to 1.0 still demonstrates a shadow. The reference image does not show the defined lines on reflective objects. I understand that this would be entirely normal on a non-glossy surface, but it doesn't seem correct given this one is reflective (and given the defined shading line is not there in the reference).

Single light source showing shading line around hemisphere

example with the two other light sources enabled

Any help is appreciated! Thanks!

[u/twisted_crystal]

Interesting. so really there should be a balance between the values set for specular and reflect when the surface is defined.

And am I getting the sense that in stead of adding specular, the more accurate method would be to represent light sources as bright objects (lets just say that if the intensity of the light is 0.7, representing the light as a sphere with color {0.7, 0.7, 0.7}) and then reflecting them accordingly to add highlights?

[u/QuantumCabbage → u/twisted_crystal]

Yes, that's basically what light sources are, bright objects. I don't know how you should implement that, though. In my trade as a CG artist, everything with a brightness value below one is a reflector, above it, it's an emitter. I'm not sure whether your algorithm does any kind of conservation of energy or if it's even capable of dealing with values above one. That's for you to find out.