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thracker11
Inspiring
July 25, 2017
Answered

Creating diffused shadows from a Parallel Light?

  • July 25, 2017
  • 3 replies
  • 8161 views

HI,

I have motion tracked a clip using 3D Camera Tracker.  I created text and extruded it and added several lights and a shadow catcher.  My problem is that I'm using a parallel light to simulate sunlight and produce the appropriate shadow.  I want to diffuse the shadow, but I don't seem to get that option with a parallel light.  I've tried adjusting the Ray-tracing Quality Setting, but it made no difference.  I also tried adjusting the AntiAliasing, but still no difference.  Does anyone have any ideas how I can diffuse the shadow for a parallel light? 

    This topic has been closed for replies.
    Correct answer Rick Gerard

    It is possible, it's just a lot of work.

    1. Before you make the layer casting a shadow 3D duplicate it and name the duplicate soft shadow
    2. Add an adjustment layer on top of the soft shadow layer
    3. Add a gradient filled shape layer above the adjustment layer with a black to white vertical gradient extending from the bottom of the layer to the top of the layer and name it track matte
    4. Set the gradient filled shape layer as a luma track matte for the adjustment layer
    5. Add a significant Gaussian blur to the adjustment layer so that the shadow layer has little blur at the bottom and a lot of blur at the top
    6. Pre-compose the soft shadow, adjustment and track matte layer and name the pre-comp shadow caster
    7. Make the shadow caster pre-comp and the layer you want to cast the shadow 3D
    8. Add a solid to the comp, name it ground, make it 3D and rotate it into position
    9. With all 3 layer selected press the A key twice to reveal the material options
    10. Set the shadow caster pre-comp to cast shadows only
    11. Set the original layer, the one casting the shadow to Cast Shadows off
    12. Set the ground layer to receive shadows
    13. Add a parallel light and adjust the point of interest to make the light fall where you want it to fall
    14. Press AA to reveal the light options of the parallel light and make sure it is set to cast shadows and the fall off is set to none or adjust it to the setting you want to use
    15. Make final adjustments of the soft shadow in the pre-comp by adjusting the amount of blur and the gradient to get the look you want

    The second option is to add a point or a spot light and adjust the light....

    Here's a project file for you to play with: Dropbox - softShadowParalellLight.aep​ (note: your browser may add a .txt extension to the file when it is downloaded. Just delete it and things should work just fine)

    3 replies

    R
    Community Expert
    Rick GerardCommunity Expert
    Community Expert
    July 27, 2017

    In the real world the sun gives parallel light and the edges of the shadows are hard. That's the way it works in nature and in AE and it makes perfect sense. I'm not sure why you would want to create soft shadows from parallel light when it's so easy to create natural looking diffused shadows using a spot light or a point light.

    My explanation was more an exercise in compositing using AE's 3D space and track mattes. The techniques I demonstrated can be used for far more than just faking a diffuse shadow.

    You also would want to be adding some ambient light whenever you are working with shadows and you need to pay attention to the falloff distance and type. There's a lot to learn.

      Mylenium
      Mylenium
      Legend
      July 27, 2017

      Rick GerardIn the real world the sun gives parallel light and the edges of the shadows are hard. That's the way it works in nature

      Not at all. It's merely a simplification going back to the olden days of computer graphics. I'm gonna spare you a detailed explanation from my POV as a physics buff...

      Mylenium

      Mylenium
      Mylenium
      Legend
      July 26, 2017

      It's not possible with AE's parallel lights. as suggested, simply use a spot light. Otherwise shadows often can be faked using layer duplicates, but without knowing anything about your comp nobody can advise specifically.

      Mylenium

      R
      Community Expert
      Rick GerardCommunity ExpertCorrect answer
      Community Expert
      July 26, 2017

      It is possible, it's just a lot of work.

      1. Before you make the layer casting a shadow 3D duplicate it and name the duplicate soft shadow
      2. Add an adjustment layer on top of the soft shadow layer
      3. Add a gradient filled shape layer above the adjustment layer with a black to white vertical gradient extending from the bottom of the layer to the top of the layer and name it track matte
      4. Set the gradient filled shape layer as a luma track matte for the adjustment layer
      5. Add a significant Gaussian blur to the adjustment layer so that the shadow layer has little blur at the bottom and a lot of blur at the top
      6. Pre-compose the soft shadow, adjustment and track matte layer and name the pre-comp shadow caster
      7. Make the shadow caster pre-comp and the layer you want to cast the shadow 3D
      8. Add a solid to the comp, name it ground, make it 3D and rotate it into position
      9. With all 3 layer selected press the A key twice to reveal the material options
      10. Set the shadow caster pre-comp to cast shadows only
      11. Set the original layer, the one casting the shadow to Cast Shadows off
      12. Set the ground layer to receive shadows
      13. Add a parallel light and adjust the point of interest to make the light fall where you want it to fall
      14. Press AA to reveal the light options of the parallel light and make sure it is set to cast shadows and the fall off is set to none or adjust it to the setting you want to use
      15. Make final adjustments of the soft shadow in the pre-comp by adjusting the amount of blur and the gradient to get the look you want

      The second option is to add a point or a spot light and adjust the light....

      Here's a project file for you to play with: Dropbox - softShadowParalellLight.aep​ (note: your browser may add a .txt extension to the file when it is downloaded. Just delete it and things should work just fine)

        T
        thracker11Author
        Inspiring
        July 27, 2017

        Hey Guys,

        Thanks so much for weighing in on this question.  I find the limitations of After Effects CC 2017, on this issue, a bit frustrating.  Maybe there will be some improvements soon.  I appreciate your responses and suggestions.

        Rick, as usual, you've gone the extra mile.  I appreciate the extra time and effort you used in helping me out with my question.  The inclusion of a sample .aep has also been very helpful.

        Again, thanks to everyone!!

        Jorge

        Dave_LaRonde
        Dave_LaRonde
        Inspiring
        July 25, 2017

        I wouldn't use parallel light.  I'd use a normal spotlight, but back it way, way up from the subject.

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