8 Replies Latest reply on Sep 25, 2015 11:19 AM by Rick Gerard

    How to use multiple cameras in same comp for mirror reflection(if that's the only way)

    DannyBooth

      Hi all,

      I am trying to create a shot where camera pans over a range of objects on table one of which is a mirror. Now I want the reflection in the mirror to move as the camera moves just like in real life. But I can not figure it out how to do it. one technique that I have imagined is to create another camera and place it on the mirror surface and then have it somehow linked to the main camera so that it records image while moving the way light ray will react to the main camera. later I can render than mirror camera to place the rendered video in the comp so that it looks like a reflection from a different side. But again I do not know how to establish that as I dont know how i can link a camera with main camera that also reacts to the movements of the cam like light reflection. Is there any expression for it ? Please help.

       

       

      Thanks.

        • 1. Re: How to use multiple cameras in same comp for mirror reflection(if that's the only way)
          Zulkifar2 Level 1

          Hi ,

          Have you already thought about using the Ray Traced 3D renderer ( or Cineware ) for the reflections?Screen Shot 2015-09-23 at 10.35.35 pm.png

          • 2. Re: How to use multiple cameras in same comp for mirror reflection(if that's the only way)
            Rick Gerard Adobe Community Professional & MVP

            Using multiple cameras will not work because only the top camera in the comp will render. The easiest solution takes the longest to render. The fastest to render takes a bit of calculation. Let's take the easy solution first. I'm assuming you are creating an entire 3D world in AE and not trying to create a reflection in a video.

             

            EZ - (not recommended):

            • Enable Ray-Traced rendering
            • Adjust the material options (press the A key twice and start sliding things around) of your mirror layer to make it act like a mirror
            • Wait forever for the render or wait a very long time for the render if you have a GPU that is CUDA compatible (NVIDIA)

             

            Complex:

            Theory: A reflection in a mirror follows a simple rule, the angle of incidence is equal to the angle of reflection so If you duplicate your 3D scene and rotate the 3D scene on the precise center of the mirror following this rule, then use a copy of your mirror layer as a track matte for the duplicate scene it will appear as a reflection. Here are the steps:

            • In the project panel duplicate the comp containing the 3D scene
            • Rename the duplicate Reflection
            • Open the Reflection comp to modify it by removing the camera and lights
            • This is the tricky part - Find the optical center of the mirror. This will be easier if the anchor point is already in the center of the mirror layer
            • If necessary, move the anchor point of the mirror to the exact center of the mirror (hold down the CTRL key and double click the anchor point tool)
            • Turn off the mirror layer visibility
            • Parent everything in the composition to the mirror
            • Make sure that the Rotation tool is set to Object axis and then rotate the mirror layer exactly 180º  on the mirror's axis to create the reflected 3D world, easiest way is to position the original mirror using rotation then change the Y orientation 180º
            • Nest the "Reflection Comp" in the original comp and collapse transformations
            • Make a duplicate of the mirror layer and use that as a track matte for the Reflection comp
            • Adjust the properties of the mirror layer to get the final look you want by using it as an adjustment layer or changing the material options or blend modes to pick up specular highlights

            There you go. Pretty simple really. The trick is in the rotation of the duplicate world.

            Screen Shot 2015-09-23 at 7.28.42 AM.png

            Here's a CC 2014/CC 2015 project file: Dropbox - Reflections.aep (note your browser may add a .txt extension. Just delete it and leave the .aep only)

            • 3. Re: How to use multiple cameras in same comp for mirror reflection(if that's the only way)
              DannyBooth Level 1

              Hi,

              Really thanks for the advice. I would try this . The first method is out of question because my graphics card is ATI FirePro V4800 and AE does not recognise this card. So rendering a ray traced shot will be very time consuming..almost impossible in my machine. I would rather try the next one.But could you please give me a CS6 version of the file because I am using CS6.

              About the shot, well I forgot to clarify something crucial. The mirror reflection will not be an exact scientifically correct reflection .. I will frame a face in that mirror at the end of the camera pan .I guess I will have to cheat the laws of physics a little bit to make it look like a face appears in the mirror as the camera moves.But it will be fairly easy I think if I apply your method. Will let you know the result.

              Thanks.

              • 4. Re: How to use multiple cameras in same comp for mirror reflection(if that's the only way)
                DannyBooth Level 1

                Hi,

                Thanks man. But I can not use ray trace becasue my card is not supported in AE. Most probably my comp will crash if I render a ray traces shot. I do not know how to use cineware.

                 

                Shib

                • 5. Re: How to use multiple cameras in same comp for mirror reflection(if that's the only way)
                  Rick Gerard Adobe Community Professional & MVP

                  I'll try and get to the project and save it as a CS6 version.

                   

                  BTW, I forgot one step - you need to scale all your layers -100% in X in the Mirror comp.

                  1 person found this helpful
                  • 6. Re: How to use multiple cameras in same comp for mirror reflection(if that's the only way)
                    Rick Gerard Adobe Community Professional & MVP

                    Here is a CS6 version of the project: Reflections(CS6).aep

                     

                    This is the corrected workflow

                    • In the Main comp make sure that the mirror's anchor point is in the center of the layer and the scale is 100%
                    • In the project panel duplicate the comp containing the 3D scene
                    • Rename the duplicate Reflection
                    • Open the Reflection comp to modify it
                    • Here's where the fun starts. Select the lights and the 3D layers and parent them to the mirror
                    • Make sure that Local Axis mode is selected in the Tool Bar
                    • Select the rotation tool and make sure that it is set to Orientation
                    • Move the cursor to the Y axis of the mirror, hold down the shift key and rotate the mirror 90º in X (should be the 4th snap)
                    • Select the scale property of the mirror layer by pressing the s key
                    • Turn off the scale lock and set the x scale to -100%
                    • This should flip the lights around
                    • Split the timelines and reveal the position properties of the cameras
                    • Add an expression to the Reflection Comp's camera position by Alt/Option clicking the stopwatch and then drag the pickwhip to the Main Comp's Camera Position
                    • Nest the "Reflection Comp" in the original comp and collapse transformations
                    • Make a duplicate of the mirror layer and use that as a track matte for the Reflection comp
                    • Adjust the properties of the mirror layer to get the final look you want by using it as an adjustment layer or changing the material options or blend modes to pick up specular highlights

                    That should do it.

                    • 7. Re: How to use multiple cameras in same comp for mirror reflection(if that's the only way)
                      DannyBooth Level 1

                      This is so so great. I do not know how to thank you sir. You solved a major problem.

                      One little question. You mentioned I have to rotate the mirror of reflection comp 90 degrees in X but I see in the file the floor layer is rotated 90.

                      • 8. Re: How to use multiple cameras in same comp for mirror reflection(if that's the only way)
                        Rick Gerard Adobe Community Professional & MVP

                        Actually that should've been 90° on the Y axis. The floor is rotated on X so that it makes a floor.