Reflections

[Peter Milner]

In this image, the right hand wall is a floor to ceiling mirror.

When using the Path Tracer engine, the light from the reflected windows does not reflect in the floor.

When using the Hybrid engine, everything reflects as it should.

Is this a fault with the Path Tracer Engine, or is there a setting somewhere that I have overlooked?

I've tried switching caustics on, increasing reflective bounces for the individual materials and increasing overall reflective bounces, but with no luck.

[Roy Hirshkowitz]

Ah-- there's what's going on.  Your metal material is being treated as a standard material as well by the translator.  It needs to be changed to a metal.  The standard materials are now designed to never go metallic in the new interface.

The ceiling lights look like a bug.

[Roy Hirshkowitz]

"Fixed" the reflection color bug...

[Peter Milner]

On this one, I've moved the sun round and you can see it shining on the wall, but it doesn't appear to shine on the floor.

[Peter Milner]

After a bit of testing it seems to be linked to the colour of the floor.

When the floor is black, the sun highlight is also black. As you lighten the floor, the sun highlight becomes more obvious. It's almost as if it's a percentage of the darkness of the floor. Looking at images on the web, even black floors should show up the sunlight.

Turning up the brightness of the sun improves things a bit, which makes me wonder if the balance between sun and sky light is not quite right.

[Roy Hirshkowitz]

Not exactly-- reflections of the solar disk are currently excluded from the calculations (they really are with the other engines as well, although I think I'm faking it for one or two of them, can't remember.)  The sun itself is very bright (as much as 4,000,000,000 cd/m^2)-- including it can burn a hole in the image or cause a lot of noise.  This is an area I'm very interested in, so I will likely revisit it soon.  We are capturing more and more paths of light-- this is one we don't quite have yet.

Currently, you can only see direct sunlight if your surface has some diffuse component.  Set the floor to be slightly less than black to get the result.  Do keep in mind that the sky has a patch around the sun that is quite bright (100,000 cd/m^2) so you will get some of the effect of direct sun on glossy surfaces.

The mirror should not be showing direct sunlight.  That's only happening because you're using the Standard material instead of the metallic material.  Of course, if you want this effect, go right ahead.  If you notice this happening in the real world, it's due to imperfections in the mirror causing some diffuse reflection.

[Peter Milner]

Sorry Roy, I was referring to patches of sunlight on the floor rather than reflection of the sun.

[Roy Hirshkowitz]

It's the same thing, when you're talking about a purely glossy floor.  Glossiness is part of the "specular" component of the material.  In order for it work properly, the solar disk has to reflect.  When you add something other than black however, you create a "diffuse" component to the material.  Diffuse reflection of the solar disk is captured properly.