View Port Lens Length from Camera Data

Rhino Rhino for Windows
1

I’m trying to match my model perspective to an image placed as wallpaper and need to know how to determine the proper lens length to input. I’ve tried using the actual lens length of the photograph as reported by Adobe Bridge as well as its equivalent on 35 mm film.

The first approach yields results that are clearly wrong. The second approach approach doesn’t seem to work either. For example, I may get a decent fit in the background or mid-ground, but the fit is way off in the foreground.

Yes, I tried the PerspectiveMatch command, but it yielded results that were clearly wrong. Perhaps it’s the cameras I’m using, which includes a Canon EOS 4Ti (18.0 mm focal length), an iPhone 7 Plus (4.0 mm focal length) and an iPhone Xr (4.3 mm lens focal length). How do I convert those focal lengths into the lens length required by Rhino?

For all photos I have the x-, y- and z-coordinates of the camera. I can measure the angle of view from the plan position of the camera and the items captured in the photo. Would the PerspectiveAngle command better achieve the results I need?

Thanks in advance for any pointers.

2

The focal lengths used by Rhino are 35mm equivalents. Various iPhones have different focal lengths, my i8 is somewhere around 28mm equivalent IIRC (I think the 7 is more or less the same)… The Canon EOS looks like it has an APS-C sensor, you can multiply the actual focal length by 1.5 to get the 35mm equivalent, i.e. an 18mm would be 27mm.

3

Thank you for your timely response.

I get a better fit in the background and midground, but not the foreground.

Should the Viewport be set to Parallel or Two Point Perspective instead of Perspective?

4

No, the camera “sees” in 3 point perspective… Other than “you need to fiddle with it”, I don’t have any better advice, maybe someone else can chime in…