HDRI Sharp shadows

[radiance]

well how does it work presently?
will making it smaller/bigger make the shadows a little fuzzy?
give us an example of the effect to look at and we'll tell you...

edit: how about 2 or 3 virtual point suns superimposed at slightly different distances, angles and strengths for a pseudo blur/penumbra?
I guess this is *a bit* like a stereo image in reverse..

that will be quite complex and slow down the engine a lot...
i think just a value to change the size of the sun should do.
if you make the sun smaller, the visible area of it is smaller and the shadows sharper.
the smaller you make it, the more 'parallel' it becomes, eg sharper shadows.

this can be implemented fully precomputed, so it does'nt any any impact at all on render times.

Radiance

[pixelrush]

Good, right , well we'll put our order in then.
One sun size slider please.

[sam75]

I don't see the point of a sun casting soft shadows if we still have a clear uniform sky. I mean soft shadows comes from obstruction of sunlight by clouds, or I got it wrong ? what is that bigger/smaller sun thing ?

I thought octane was closer to maxwell and fryrender but all this sounds more like other biased engines.

[radiance]

I don't see the point of a sun casting soft shadows if we still have a clear uniform sky. I mean soft shadows comes from obstruction of sunlight by clouds, or I got it wrong ? what is that bigger/smaller sun thing ?

I thought octane was closer to maxwell and fryrender but all this sounds more like other biased engines.

Hey,

We're talking about the soft parallel shadows caused by the fact that the sun is a disc with an area instead of an infinitely small point in the sky.

The sun / sky code in octane is the same one used in all the others (maxwell pre 2.0, fry, indigo, lux, yafray, vray, blender, etc...), they are all based on the same paper.
(except maxwell, which has a modified one since they're 2.0 version)

Radiance

[sam75]

I don't see the point of a sun casting soft shadows if we still have a clear uniform sky. I mean soft shadows comes from obstruction of sunlight by clouds, or I got it wrong ? what is that bigger/smaller sun thing ?

I thought octane was closer to maxwell and fryrender but all this sounds more like other biased engines.

Hey,

We're talking about the soft parallel shadows caused by the fact that the sun is a disc with an area instead of an infinitely small point in the sky.

The sun / sky code in octane is the same one used in all the others (maxwell pre 2.0, fry, indigo, lux, yafray, vray, blender, etc...), they are all based on the same paper.
(except maxwell, which has a modified one since they're 2.0 version)

Radiance

Hi

But as far as I know neither maxwell nor fryrender have such an option for controlling sun size, we can with lens and exposure but it's related to the camera not to the "real" size of the sun nor the shadows it casts.

Would a simple slider to control hdr accuracy be that hard to implement to octane ?
And also being able to replace the physical sky by a hdri sky while keeping the sun ?

[simmsimaging]

I have no idea if the sun size will have an impact on shadow sharpness or not. If the model is fairly accurate to reality then I kinda doubt it, as over the kind of distances we are talking for sun-rays they are effectively parallel at any size. I'm not sure how the math is setup though, so maybe it would work.

The typical softer shadows you can get from the sun are (AFAIK) caused by clouds or atmospheric haze etc. However, I'm not really concerned (personally) with the methodology, but would love to have the option to adjust shadow sharpness to make it easier to integrate renders with actual photographs, where for sure you will find the effect quite often. It will also allow us "non purist" users to use the sun as an optional added studio-type light

Anyway, don't care to start any uproars over "accuracy", but if can be done there will likely be a large (and probably largely silent) group that would like it and use it.
Just my POV.

b

[gristle]

One trick would be to place the scene inside a large single sided (or double sided ) sphere that has a frosted finish...
Probably kill the render time however.

[n1k]

I have no idea if the sun size will have an impact on shadow sharpness or not.

Well, in Vray when you increase size of the Sun, shadows become softer.

Cheers,
n1k

[sam75]

One trick would be to place the scene inside a large single sided (or double sided ) sphere that has a frosted finish...
Probably kill the render time however.

haha I thought about the same joke

[vinz]

+1 ...