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emilyn26405795
Participant
September 4, 2021
Question

CC Radial Blur: Cannot Place Centre Out of Shot

  • September 4, 2021
  • 2 replies
  • 1057 views

I'm making a title sequence for a film. The idea is that it looks like a theatre stage, with spot lights moving around to show the various titles. All of my light sources will be out of view as they would be in a theatre. What I would like is to add beams of light as if the spot lights are shining through smoke. I've added a white circle (3D shape layer) and used javascript expressions to size and move the circle into the beam of the spot light. I have then used CC Radial Fast Blur to turn the circle into a beam. The centre of the blur effect is the location of the spot light but using 'toComp' to convert it to 2D coordinates.

 

The above has all worked really well, if the light source is within the shot. As I move the spot light location out of shot, the centre of the blur effect does not move out of shot. I should highlight, the coordinates do move out of shot but the appearance does not follow. I've tried setting the centre manually so I don't think it's anything to do with parenting or calculations.

 

A couple of screen shots attached to illustrate. Sorry if this makes no sense at all. Any help would be gratefully received.

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2 replies

Mylenium
Mylenium
Legend
September 5, 2021

Most of the CC effects restrict the output buffer size to the comp or layer source size. that's a historic limitation coming from a time where this was critical to prevent excessive memory consumption on much weaker system's, obviously. Somehow they never worked on that later, it seems. You may want to find an alternate blur effect fro ma third-party suite like Boris Continuum or Sapphire.

 

Mylenium

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    emilyn26405795Author
    Participant
    September 6, 2021

    Thank you Mylenium, that's great insight and explains why it isn't working. Maybe something Adobe improve in the future. Really appreciate your help.

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    Community Expert
    Rick GerardCommunity Expert
    Community Expert
    September 4, 2021

    Cropped and not embedded* screenshots don't tell us much. We need to see the whole UI with the modified properties of the problem layers shown. Select the layers, press the 'u' key twice, and use the toolbar, or drag or paste the screenshots in the reply field so we know what is going on in your shot. 

     

    I have faked a lot of spotlight beams over the years and I cannot remember ever using CC Radial Fast Blur to create one. Most are masks, some are masks combined with gradient track mattes. Almost always, unless I'm using Trapcode Lux or Trapcode Shine, the spotlight effect will start out with a shape layer or a solid with a mask and some blend modes. 

     

    I am guessing that you positioned your ellipse somewhere in the comp and then used this expression to tie the CC Radial Fast Blur/Center to the position of the spotlight.

     

    L = thisComp.layer("Spot Light 1");
L.toComp([0,0,0]);

     

    The problem is that the circle then also has to be moved so that it is on the line between the Spot Light 1/Position and the Spot Light 1/Anchor point. That complicates things quite a lot. I don't think the approach is viable because of the way CC Radial Fast Blur works when the blur center is outside of the comp frame. Even if you fixed the position problem, you won't get a realistic look that way. 

     

    You would probably be better off using Window/Create Nulls From Paths/Points follow Nulls script on a 3 pointed mask and then tie one of the nulls to the position of the spotlight using the toComp expression I have shown. Fractal noise and some directional blur or just Radial Blur would probably do it. 

     

    * The "Drag & Drop here..." area is buggy and should not be used to share images. Please use the toolbar or just drag your images to the reply field.

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      emilyn26405795Author
      Participant
      September 4, 2021

      Thanks Rick, that's really helpful. Sorry, I'm pretty new to After Effects (and completely new to the forum) so I'm probably using all the wrong terminology. Using a triangular solid or mask is a great idea so I'll give that a go if I can't work this out.

       

      I'm attaching a further screen shot to show the settings. You're quite right, I'm using 'toComp' in that way. Positioning and sizing the ellipse wasn't too bad (unless I've done it totally wrong of course). I'm fairly sure there isn't a problem with this part because switching off the formulae doesn't solve the problem. It seems to me that CC Radial Fast Blur doesn't allow a centre that is out of the camera's view. If the spot light location is within view it works perfectly. If I move the light out of view, the centre doesn't appear to move past the edge of the frame (though the actual point does move correctly). I just hoped I'd missed something obvious. Example project also attached.

       

      Thanks again. Will have a go with the mask approach.

       

       

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