Mo-blur: way, way slower to render at higher shutter speeds?

[simmsimaging]

Not sure if this to be expected, I don't use mo-blur that often. Trying to shorten up some motion trails, but as I advance the shutter speed (Vrayphysical camera for the blur) the render is stalling out. Going from 200 to 400 literally crippled the render - had to kill it.

Is that normal/expected? Seems to me it would render faster as there was less blur?

/b

[Macker]

Surely you can't be seeing much motion blur at speeds that fast?

[simmsimaging]

You wouldn't think so, but if I wasn't seeing it I wouldn't have bothered to post

Testing indicates that the mo-blur samples (in the Vray properties) need to be radically tuned down as the blur length becomes shorter or the render times really spike. Expected?

b

[joconnell]

Seems a bit odd alright - you'd think that with the samples of the object being closer together with the reduced motion blur time that the samples would be closer together and thus easier to clean?

[simmsimaging]

you would think , but it doesnt seem to be working that way. Anyone confirm?

b

[joconnell]

What way is your scene lit Brett - any other factors that might be involved? Things like highlights, hdrs, reflections?

[kriscabrera15]

whats you ISO set at?

[svetlozar.draganov]

Can you post a sample scene ?

[simmsimaging]

Sorry guys - don't know why but am not getting any topic update emails all of a sudden.

@John: it was lit with Vraylights, lots of reflections and refractions - but that stuff was consistent, just the shutter speed was changing.

ISO - can't remember now, but was probably around 200-400

Scene: I can, but I have to do it next week now. I am badly crunched for time and had to do the mo-blur in post to get by. WIll do though!

[joconnell]

I wonder is it that the more focused (less motion blurred) the objects were, the higher the concentrations of very bright values was and thus harder on the sampler?