What should Shadow Blur Radius be for a bright, sunny day?



  • @3dcheapskate Here's what the Poser Reference Manual says which is where I tried to take my answer from:

    The Shadow Blur Radius parameter specifies the radius of this blurry region. By default, this dial is set to a low value. Raising the blur radius increases the soft shadow edge effect.

    So generally, in math, Radius is a measure of distance or length, not angles.


  • Poser Ambassadors

    Light is a strange thing. In 3D we have to fake it. That was where the "old style AO faking" came from.

    => => It depends to a very large extend on your light setup. Wanna be true to life or cheat?

    If :

    • You render with GC ON at 2.2 and IDL enabled
    • You render in a IDL dome
    • If you have only a single infinite light "playing Sun".
      So sorry, but planet earth has only ONE Sun shining on dust particles polluted air bringing us the IDL.

    Your best bet would be a SBR between 10 and 15.

    But everything changes the second you add a second light, because the moment you added that second light, you started "cheating" again.

    So, For outside renders => Render inside an IDL Dome + a Single Infinite light to "play sun" + GC and an SBR of around 10-15 to start with.


  • Poser Ambassadors

    I'll second 0.5; that's what I use because I remember @bagginsbill recommending that as appropriate for full sunlight with an infinite light some time ago (possibly on the Rendo forums). Using a larger number will soften the shadows & is useful for approximating more overcast conditions.



  • @vilters You should never use a second light in an out door daytime render. It'll look off. Skydome and 1 infinite is all you need. If the HDRI you are using is of a very overcast day you can just use the skydome.


  • Poser Ambassadors

    @ghostship
    That is what I said : A good IDL dome and a single Infinite light.



  • Many times I add fill lights to outdoor scenes.
    Basically to add to the reflected light in the scene
    Simply because nothing in an hdri is close to the figure like it would be in real life, or in many hrdi photos



  • @vilters said in What should Shadow Blur Radius be for a bright, sunny day?:

    Light is a strange thing. In 3D we have to fake it. That was where the "old style AO faking" came from.

    => => It depends to a very large extend on your light setup. Wanna be true to life or cheat?

    If :

    • You render with GC ON at 2.2 and IDL enabled
    • You render in a IDL dome
    • If you have only a single infinite light "playing Sun".
      So sorry, but planet earth has only ONE Sun shining on dust particles polluted air bringing us the IDL.

    Your best bet would be a SBR between 10 and 15.

    But everything changes the second you add a second light, because the moment you added that second light, you started "cheating" again.

    So, For outside renders => Render inside an IDL Dome + a Single Infinite light to "play sun" + GC and an SBR of around 10-15 to start with.

    I still say 10-15 is rather high. According to the manual.



  • @shvrdavid I suppose on indoor shots maybe with colored mesh lights??? Out door scenes work just fine without that as long as you light the skydome properly. Here the sun in behind the subject so most of the light is from the skydome.

    0_1525816477612_Camping.jpg


  • Poser Ambassadors

    If there are absolutely no clouds or haze in the atmosphere, the correct SBR is .5. And it is degrees.

    It's not wrong to use more (like up to 1) if the sun is passing through a lot of water vapor.



  • @bagginsbill said in What should Shadow Blur Radius be for a bright, sunny day?:

    If there are absolutely no clouds or haze in the atmosphere, the correct SBR is .5. And it is degrees.

    All right then. I obviously don't know what I'm talking about. So forget everything I said.



  • @caisson said in What should Shadow Blur Radius be for a bright, sunny day?:

    I'll second 0.5; that's what I use because I remember @bagginsbill recommending that as appropriate for full sunlight with an infinite light some time ago (possibly on the Rendo forums). Using a larger number will soften the shadows & is useful for approximating more overcast conditions.

    Found that one (or at least one of them) - 22 Apr 2015:

    https://www.renderosity.com/mod/forumpro/?thread_id=2889971&page_number=2#msg4200771

    (just spotted bagginsbill's post above which reconfirms)



  • @eclark1849 said in What should Shadow Blur Radius be for a bright, sunny day?:

    @3dcheapskate Here's what the Poser Reference Manual says which is where I tried to take my answer from:

    The Shadow Blur Radius parameter specifies the radius of this blurry region. By default, this dial is set to a low value. Raising the blur radius increases the soft shadow edge effect.

    So generally, in math, Radius is a measure of distance or length, not angles.

    Ah yes, in maths (or math if you prefer) radius is distance, but in Poser Manual speak it could be anything - time, weight, Jessis, etc... ;o)

    ( You don't actually believe that the manual speaks the truth, do you ? )



  • @bagginsbill said in What should Shadow Blur Radius be for a bright, sunny day?:

    It's not wrong to use more (like up to 1) if the sun is passing through a lot of water vapor.

    Phew, imagine the steam created by that !



  • @ghostship "Called fourex and spelt 'XXXX' 'cause Queenslanders can't spell 'Beer'" ;-)

    I can't count the number of times I have seen "behind the scenes" footage of photoshoots where crew members are holding up a big reflector. Absolutely zero difference from an area light used for fill, especially if the primary (Sun) illumination is somewhat behind the model and therefore casting shadow in the direction of the camera. If the real world professionals aren't afraid to augment inconvenient daylight when outside, then Poser artists certainly shouldn't be.


  • Poser Ambassadors

    @anomalaus

    Totally agree; But the same "thing" goes for make-up.

    Make-up, eyeliner, nailpolish, plastic boobs, and the list goes on and on.
    The lot is also to , tja, how to put it without stepping on toes. . . . . . make something not so perfect, "look" perfect. LOL.

    It is like so many things in life.
    We "fake" to look better, stronger, more appealing to the other side of the hormones. LOL.

    For years people have been complaining that I hang my Poser boobs too low.
    Tja, I live in a continent where we still have something called "gravity". (even with a Poser bra) LOL.

    So, in my Poser scenes, there is only ONE Infinite light inside an IDL dome.



  • @anomalaus I have tried using an area light like a reflective/bounce card. It's gotta be used tastefully or it'll ruing the lighting. Too much and it just looks like photo-flash with a cheap camera. OTOH if that is the loom you are after then that's what you do.
    0_1525900407020_Photoflash.jpg


  • Poser Ambassadors

    Cheap fill flash would give harder shadows than that as the light source is physically small. An area light would be equivalent to a softbox which is directly emitting light from a flash unit, rather than a reflector which is passively bouncing it back. Reflectors are used as a more subtle alternative to fill flash as it can easily be too harsh. I'd try using a polygon mesh (like the simple square primitive) with a white (or maybe gold) diffuse material.

    I made a demo a while ago on bounced/indirect light, thought I might as well post it. This scene is using a single infinite light at 100% intensity plus the Blackout material applied to the default Ground (the Construct) -

    0_1525904847055_demo1-black.jpg

    Exactly the same setup with one change - the White material has been applied to the Ground -0_1525904953321_demo2-white.jpg

    The materials are in the default installation in Materials/The Construct. They are diffuse colour only - the environment is not emitting light at all. The parts of the scene receiving direct light from the infinite light don't change, but the rest of the scene is transformed as the areas that are lit indirectly by bounced light pick up colour & value from the environment. Superfly does real ray traced reflections all the time which is why it must have a 360 degree enclosed rendering environment; that environment could be a simple diffuse colour, or an HDRI pano, or a JPG, or a complete 3d environment. It depends on what is required but whatever it is it will have a massive influence on the scene & is as important as any direct lighting.



  • With Infinite light and shadow blur radius I prefer to use 1-2 or around this figure,but sometimes I use higher number for indoor renders where I use high numbers like 10 and more and agree with guys who use extra fill lights,I use large or larger area lights which are further from figure like in this render,I used infinite light with low intensity and two area lights with 65-75%

    Edited in Photoshop,edited only curves with Camera RAW filter and render has been exported as OpenEXR

    alt text

    Hope this helps

    Thanks,Jura



  • A quick reference from the real world - I find that that can sometimes help clarify things.

    Here's thee shadow of a plant (leaves about 1m from the ground) on a gloriously tropically sunny day.

    Top photo - no clouds in front of the sun, but possibly a slight overall atmospheric haze.
    Subsequent photos - a cloud passes in front of the sun.

    I used the auto setting on the camera, so exposure is different for each photo.

    Question: what Poser infinite light settings would you change to mimic (fake if you prefer) this effect ?
    I'd guess both Shadow Blur Radius and Shadow Strength ?
    0_1525929548762_shadow.jpg



  • You could try to mime the effect of the atmosphere haze and the clouds on the direct sunlight by a large surface, say a dome, with variable transparency and noise on the IOR.
    A second dome, not casting shadows, could be used to add the atmospheric diffusion light.