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Any Tips on Aligning Mirror Reflection, Subject and Camera

Db3dDb3d Posts: 248
in Technical Help (nuts n bolts)

Any Tips on Aligning Mirror Reflection, Subject and Camera?

I understand that the anlge of reflection is the oposite of the angle of incident.  But, is there an easy way to align a reflection in a mirror with your subject and camera?

Example.  You have someone looking in the mirror, but you want the camera to pick up the face in the mirror.  I can turn on NVIDIA Iray preview rendering, but when I go to reposition anything in the scene, the image goes to the white figures until it re-renders.

I thought about looking at a top view and aiming the camera at the oposite angle of the subject, but even that's hit-n-miss.

So, anyone have a surefire way to do this quickly?

Comments

  • felisfelis Posts: 4,669

    If the character is looking at itself in the mirror, this means that the character needs to be in front of the mirror.

    And if you then wants to be able to see the face in the relection from the mirror the camera has to be close to the character head in terms of angle, depending on the size of the mirror.

    Assuming that the mirror is vertical, you need the camera in around the same heigth as the character, and then I think a top view would be the easyest way to position the camera.

  • Db3dDb3d Posts: 248
    felis said:

    If the character is looking at itself in the mirror, this means that the character needs to be in front of the mirror.

    And if you then wants to be able to see the face in the relection from the mirror the camera has to be close to the character head in terms of angle, depending on the size of the mirror.

    Assuming that the mirror is vertical, you need the camera in around the same heigth as the character, and then I think a top view would be the easyest way to position the camera.

    I understand all of that.  If the mirror is positioned vertical at 180-degrees and the camera is aimed at the center of the mirror at 20-degrees and 10', then the subject has to be at 160-degrees at 10' to be centered in the mirror.  I fully understand the physics of reflections.

    My question is there an easier way to set the character+mirror+camera in order to remove some of the guess work and trial and error since the angles presented in the parameter tabs are based on the items position in the render scene.  (Yeah, I guess I could go through all the mathematics to calculate the (x,y,z) cooridinates and angles, but that's a bigger pain than trial-and-error.)

  • Db3dDb3d Posts: 248

    Hmmm... Maybe I could take a primative plane and place a .png image of a protractor on it, lay it parallel to the floor and use that to position the figures from the TOP camera.  Make everything in the png file transparent except for lines at 10-degree increments from 0 to 180-degrees.   I might just try this.

  • Richard HaseltineRichard Haseltine Posts: 102,701
    edited August 2019

    https://www.daz3d.com/measure-metrics-for-daz-studio will let you set up angle measures. You could also use cylinder primitives, in this case perhaps on postiive Z, place their bases on the mirror surface, and see what angle you needed to y-rotate them to to point at the figure or camera (perhaps parent a Null to the target and set the cylinder to pont at the null).

    Post edited by Richard Haseltine on
  • Db3dDb3d Posts: 248

     

    I looked at the Measure Metrics and wasn't sure if that would do what I want.  I might purchase it if I give up with other methods.

    Your idea about the cylinder could work too.  That might be the easiest way.  I'll have to play with it.

    I've attached the end results of my trial-and-error method.  

     

     

    Richard Haseltine said:

    https://www.daz3d.com/measure-metrics-for-daz-studio will let you set up angle measures. You could also use cylinder primitives, in this case perhaps on postiive Z, place their bases on the mirror surface, and see what angle you needed to y-rotate them to to point at the figure or camera (perhaps parent a Null to the target and set the cylinder to pont at the null).

     

    Charlotte8BreDVirgH M3M2painting2R2REND.JPG
    1280 x 1792 - 459K
  • Db3dDb3d Posts: 248
    Richard Haseltine said:

    You could also use cylinder primitives, in this case perhaps on postiive Z, place their bases on the mirror surface, and see what angle you needed to y-rotate them to to point at the figure or camera (perhaps parent a Null to the target and set the cylinder to pont at the null).

    Richard,

    You're a genius.  Got my camera and subject positioned perfectly the 1st time using your suggestion.  

    For anyone else following, here's a step-by-step of what I did.

    a) create a primative cylinder that was 6' high 6' diameter.  It lands on the stage at (0,0,0).

    b) added my vertical mirror which also comes in at (0,0,0)

    c)  Note:  it is important that the mirror and cylendar remain centered together.

    d) added my figure and camera and switched to TOP view

    e) positioned my figure where I want it

    f)  rotated the cylindar so the Y axis was point to the figure.  (In my case, it came out to -22 degrees)

    g) rotated the cylindar to +22 degrees and noted where the Z-axis arrow was pointing

    h) moved my camera so the dashed center line of the camera was aimed directly at that Z-axis arrow.

    i) turned off visibility on the cylindar

    j) switched to my camera and rendered in iRay

    k) my figure was centered perfectly in the mirror

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