Page 2 of 2 FirstFirst 12
Results 16 to 20 of 20

Thread: HDRI & Limit Dynamic Range Questions

  1. #16
    RETROGRADER prometheus's Avatar
    Join Date
    Aug 2003
    Location
    sweden stockholm
    Posts
    15,863
    Quote Originally Posted by gerry_g View Post
    might have thought so once but by adding a light to the horizon and turning on scattering I find I can beef up the look of where the fog hits the ground in a way I can't do otherwise, makes it more like the old volumetric where you get a total white out but without the cost if you are careful
    Donīt we have a thread with the global scattering somewhere, I also posted a couple of scenes, there, not sure it was global scattering or the primitive item...(edit..think it was mostly primitive item in volume mode)


    https://forums.newtek.com/showthread...volumetric+fog



  2. #17
    LW Junkie squeegie's Avatar
    Join Date
    Aug 2003
    Location
    Central Florida
    Posts
    97
    It appears my lack of skill seems to be the biggest hurdle, but you guys are always such a huge help!

    Yeah, I had the old model enabled before I had packaged it, but honestly I couldn't tell the difference ( I feel like I am forever playing catch up with learning LW). I am really beginning to think the problem was in the original HDRI I was using itself rather than the fog. I may just end up using Physical Sky and comping in some clouds in PS.
    The render hit on Global Scattering was way more than I was willing to invest, as the original scene is quite large.
    <insert clever signature here>

  3. #18
    RETROGRADER prometheus's Avatar
    Join Date
    Aug 2003
    Location
    sweden stockholm
    Posts
    15,863
    Quote Originally Posted by squeegie View Post
    It appears my lack of skill seems to be the biggest hurdle, but you guys are always such a huge help!

    Yeah, I had the old model enabled before I had packaged it, but honestly I couldn't tell the difference ( I feel like I am forever playing catch up with learning LW). I am really beginning to think the problem was in the original HDRI I was using itself rather than the fog. I may just end up using Physical Sky and comping in some clouds in PS.
    The render hit on Global Scattering was way more than I was willing to invest, as the original scene is quite large.
    Theres really no quality control directly in global scattering, it is controlled in the light itself...and it often needs very high amount of volumetric samples to resolve grain, they really need to adress this in upcoming lw releases.

    - - - Updated - - -

    Quote Originally Posted by squeegie View Post
    It appears my lack of skill seems to be the biggest hurdle, but you guys are always such a huge help!

    Yeah, I had the old model enabled before I had packaged it, but honestly I couldn't tell the difference ( I feel like I am forever playing catch up with learning LW). I am really beginning to think the problem was in the original HDRI I was using itself rather than the fog. I may just end up using Physical Sky and comping in some clouds in PS.
    The render hit on Global Scattering was way more than I was willing to invest, as the original scene is quite large.
    Theres really no quality control directly in global scattering, it is controlled in the light itself...and it often needs very high amount of volumetric samples to resolve grain, they really need to adress this in upcoming lw releases.
    Still think it is easier to control both quality and fog level with primitive item in volume mode.

  4. #19
    RETROGRADER prometheus's Avatar
    Join Date
    Aug 2003
    Location
    sweden stockholm
    Posts
    15,863
    I need to create a bug content scene for the global scattering, I do not think it behaves correctly when used together with volumetric items as clouds, occasionally I can get a bit of decent quality when having global scattering and godrays, but with the new sunlight and setting a volumetric distance properly to allow for that sunlight to yield godrays/sunbeams when hitting clouds from behind for instance, or almost from behind..it will generate a sharp ray cutoff...leaving sort of a dark edge around the clouds..it shouldnīt look like that.

    Now..I tried by instead using a volumetric item to serve as the scattering medium..and with that I do not get that kind of artifact, with that seupt...it excludes the lights volumetric distance since I do turn off the global scattering and thus no effect with that.
    So a bit sad that the global scattering isnīt working optimal by providing proper quality when used together with volumetric items such as clouds, it has nothing to do with the lights volumetric samples, camera samples doesnīt do anything either..and asymetry can help tone it down..but then it would loose the genera ray effect.

  5. #20
    Quote Originally Posted by squeegie View Post
    It appears my lack of skill seems to be the biggest hurdle, but you guys are always such a huge help!

    Yeah, I had the old model enabled before I had packaged it, but honestly I couldn't tell the difference ( I feel like I am forever playing catch up with learning LW). I am really beginning to think the problem was in the original HDRI I was using itself rather than the fog. I may just end up using Physical Sky and comping in some clouds in PS.
    The render hit on Global Scattering was way more than I was willing to invest, as the original scene is quite large.
    Hi,
    the problem occurs when a very bright light is scattered (e. g. by subsurface scattering, GI, high roughness or similar). The sphere surface has a roughness of 50% (which is very rough) and the hdri has a bright light, the sun (this may differ from hdri to hdri).

    The "correct" solution would be to increase the reflection samples. But that increases the render time enormously.

    Ways to get rid of the bright pixels without increasing the render times are:
    "Limit dynamic range" can help but will limit the dynamic range of the whole image (in the example a bit exaggerated).
    "Despike" is designed to find and remove individual bright pixels.
    You can set the "Reflection Limit" to something lower (you loss dynamic range only for reflections).
    Turn off "Glossy Reflection" for the surface is in my opinion not a valit solution (with a few exceptions). You loss the hole indirect reflection and a big piece of realism .

    Here is a comparison of the possibilities; final render and specular indirect buffer (where the problem occurs):

    Click image for larger version. 

Name:	Vergleich_02.jpg 
Views:	19 
Size:	486.7 KB 
ID:	146855

    Since all renders are different you have to decide from case to case which method is the best one for you.

    ciao
    Thomas
    Web: www.dieleinwandhelden.com

    I use two pieces of the three-piece application with mocap module.

Page 2 of 2 FirstFirst 12

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •