Hi everyone,
In Ask The Trainer, the theme of frame-padding showed up.
Intro
Some questions come up from time to time. One of those classic questions is: How to keep the image content in the exact frame resolution while adding a frame around it? I think for two decades, I have gotten this question.
If the frame is equal around the picture, the frame ratio will change! So, in this new version, I added both (vertical and horizontal padding). This works for equal padding or for different padding to keep the image ratio the same.
1
One option to solve it
I hope the quick screen capture gives sufficient information to use it successfully.
https://www.amazon.com/clouddrive/share/TPLgTAhhvJluucj9EefJma2rLRSshHgKlr4M7XpT0ZR
Click on the XPresso Icon to get to the UserData.
Some thoughts about frame padding
In 3D, we measure renderings in pixels, the rendering in mm has to do with your idea of DPI (dots per inch), which translates the inches into a specific amount of pixels added accordingly. DPI is not a fixed ratio.
Move the camera?
To pull the camera back is not an option. Any change of the POV (point of view) will change the complete perspective of the image. With this, the composition among objects in various depths will change, perhaps dramatically.
Field of View!
The way to do it is to change the FOV (field of view) while the POV and the camera itself stay precisely as before.
Depth of Field
Increasing the FOV will change the length of the lens. With this, the formula for the F/number (fraction) will change. To achieve the same DOF (depth of field) if needed, this needs to be adapted. Focal length divided by the (optical) size of the aperture will give you the F/number. This needs to be the same, which might work with very wide FOV not really possible. A lens with a focal length of 36mm and an F/8 aperture would have an equivalent optical aperture of 4mm in diameter. If we go to an 18 mm lens also with F/8, the optical equivalent of the aperture would be F/2.25mm. Much smaller and with that a larger DOF.
2
Sensor Size, an alternative way, quick and simple.
A nice little trick is to increase the sensor size and increase the render resolution in the same way. So the short version is, multiply the sensor size and then the render-resolution with the same factor, both numbers. Why was that not mentioned on top of this post? Because the question was about equal padding, and that is a little bit more work, just add twice the padding to height. See screen capture:
https://www.amazon.com/clouddrive/share/O2QvaQBrAcY2jkDjgnBwUthOf11QO7lsgq2jMcdsZVo
Note
Each option might have limitations or downsides, so please test before going into production. Any change to the image that is done globally will be changed, of course, if it is lens distortion or light flares (a wider lens will “see” more), etc.
All of this works, as we use a flat focal plane in Cinema 4D, like most modern lenses provide.
Enjoy