Small Bright Speckles - no GI

[Morne]

Hi all

I have a scene without GI, only VRaySun, VRayAmbientLight, HDRI Environment map. I have small bright random speckles (almost like I have a diffuse override with splat map)
All shaders are VRay. I mostly see it on my reflective surfaces, more so on anything metal. It's not noise from too low subdivs, its something else. (Because reflection and rawreflection element looks different to the speckle in beauty) Light and Rawlight element also doesnt leave any clues. Arrrgg!

I'm thinking it has something to do with lights or something such as settings sun to invisible - but this doesnt do anything.

DMC - 2, 16
Quadratic filter (does same without this)
Sampler 0.85, 0.01

Its for an anim and I'm, hoping motion blur will help smooth things out, but still, I often get this and can never pinpoint from what it is from.

(Sorry I can't show screenshots)

[Morne]

As a last option I can tick subpixel mapping and clamp on to maybe 2 or 3, but I would prefer to avoid this

[kosso_olli]

We have this all the time, and it is hugely annoying. And it is always happening on glossies. Enabling subpixel mapping doesn't change anything at all.
I am pretty sure that in your scene the speckles are coming from the HDRI. Let me guess, is there a very bright sun in it? That's often the case in our scenes. If you clamp the HDRI at values around 10 (using the colorcorrect map from here: http://www.cuneytozdas.com/software/3dsmax/), the speckles go away, but your shadows will be much softer. A trick to avoid this is to put a second domelight in the scene, which only affects diffuse and specular. Put your unclamped version into that one. The clamped HDRI goes into the other domelight, which has only affect reflections enabled. Hope this makes sense...

[Morne]

enabling subpixel and clamp at 2.5 solved it in my case
(I dont have a dome light in my scene)
But I might stick the hdri in one

[vlado]

These are usually caused by reflection rays hitting some bright hilight or a bright portion of the hdr map. Using a dome light might help; using sub-pixel mapping also works.

Best regards,
Vlado

[Morbid Angel]

These are usually caused by reflection rays hitting some bright hilight or a bright portion of the hdr map. Using a dome light might help; using sub-pixel mapping also works.

Best regards,
Vlado

for example if your hdr had a sun in it, which is a dot under the lowest exposure, then sampling that will most likely create this kind of effect. This is common in other renderers too, we had that problem with mental ray many times. The solution typically is to clamp the hdr and use a sun light instead.