Loading...
> >

Lights and Render Time

kocammykocammy Posts: 65
in New Users

Hello Again,

I have a question about adding lights to a scene and their impact on the time it takes to render the scene.

I'm using 3Delight and the scene I'm working with takes approximately 10 minutes to render with no lights added to it.  However when I add a single area light (from Studio Light Pro 4.6) the same scene takes hours to render.  Its rendering now and is at 2% after 28 minutes.

Here are my settings; Bucket Size 16 Max Ray Trace Depth 2 Pixel Samples 8 Shadow Samples 16 Gain 1 Gamma Correction Off - Gamma 1 Shading Rate .2 Pixel Filter - Sinc Pixel Filter Width 8

Is it normal for render time to increase so dramatically by using a single light in the scene rather than just relying on the hedlamp and no added lights?

Thanks,

Cammy

Comments

  • SzarkSzark Posts: 10,634

    yes mesh lighting will increase the render times but also consider your surfaces, are they reflective, do they have displacement mapping etc etc. If you are not using any raytrace functions like reflections, refraction and SSS the you can lower the Max Ray Trace Depth to 0 and you will still get Ray Traced Shadows and quicker render times. Of you are just using Ray Traced reflections you could use 1 and you will only get a reflection of anything in the scene, 2 will give you a reflection of a reflection and so on.

  • kocammykocammy Posts: 65

    Thanks!  It took the attached scene just over an hour with a single area light applied. The scene I'm currently rendering has anothe figure in it an the lights are brighter but it's taking so much longer - I'm at 8% after 2 hours and 20 minutes. Can brighter lights make it take that much longer?

    Thanks for your help!

    Stacey Hears Michelle Come Home (Lights Area Med White Default).jpg
    800 x 796 - 223K
  • mjc1016mjc1016 Posts: 15,001

    Go to the Area Light and post the light parameters for it (if/when it  finishes...).

    There are usually other settings on area lights that can pump up the render times.

    Also, what is the skin shader on the additional figure?

    What's the render size?

  • kocammykocammy Posts: 65

    Thanks - relly stupid question when you say go to the area light - how do I do that?

    The render size is 800 x 800.  The skin shader on both figures are each generic Genesis 2 shaders.

    The attachment above is supposed to be darker - she's in a dark room.

  • mjc1016mjc1016 Posts: 15,001
    edited December 2015

    In the Surfaces tab, Area Lights are surface properties...there will be a Light settings for what ever has the Area Light shader on it.

    The default G2F shader is UberSurface...so there is a switch for Occlusion. There should be 3 controls there a switch, a dropdown box and a slider.  Set the switch to  'On' and in the box pick (Ocllusion Shading Rate Mode) 'Global' .  Flipping that to Override will activate the Occlusion Shading Rate slider (3rd control).  Leave that at 10 (higher is 'faster')...that should give you a boost in speed.

    Also, since you are not using Depth of Field (at least in the one posted) or Motion Blur, drop the Pixel Samples  AND the Filter Width back to their default values...they aren't doing much, except increasing the render time.

    And, unless these are 'final' renders, the overall Shading rate of 0.2 is just slowing things down...bumping it up to 0.5 or even back to the default of 1 will make things much faster.

    This render, using a single area light and the settings I said above (Shading rate of 1.0) and Max Raytrace depth of 8 rendered in 3 and a half minutes on a quad core 2.3 GHz, 8 GB RAM machine...at 1000 x 800.

     

    All the materials are default (except for the overrides)

    rendersettings.png
    1000 x 800 - 1M
    Post edited by mjc1016 on
  • mjc1016mjc1016 Posts: 15,001
    edited December 2015

    And for the kicker...turn Progressive Rendering 'ON' in the Render settings..

    Same scene...same everything, except Progressive is ON...


    Render time: 2 minutes and 6 seconds!

    rendersettings2.png
    1000 x 800 - 1M
    Post edited by mjc1016 on
  • mjc1016mjc1016 Posts: 15,001
    edited December 2015

    And I'm not going to bother posting the last render I did...just chaged the lighting a bit and that barely affected the render time.  Dropping the light level rendered in 2 minutes, 6.44 seconds...as opposed to  the 2 mins 6.12 seconds last time.  That's well within the margin of variability for a render...basically anything under about 5 difference means 'it's the same time'.

    Post edited by mjc1016 on
  • SzarkSzark Posts: 10,634

    Check out my Area Light tutorail listed on my render page, link is below.

  • kocammykocammy Posts: 65
    edited December 2015

    Thanks everyone for all the help - I really appreciate it!

    MJC 1016 - What did you mean by "final" renders?  Is there a way to keep rendering an image?  Thanks again!

    Post edited by kocammy on
  • mjc1016mjc1016 Posts: 15,001

    Final render: something you are comp;letely satisfied with the lighting/settings and are rendering for publication/posting to a gallery....something that you won't want to teak any more.

Sign In or Register to comment.