I'm using an ARSKView which blends 2D SpriteKit with 3D ARKit. When it displays the camera AR experience, I notice that the field of view of the camera is a bit narrow (in portrait mode). It's equivalent to 1.5x zoom in the built-in camera app.
I would like to zoom out, or widen the field of view a bit... even if it's just to the same 1x resolution that the built-in camera app allows.
Is there any way to do that?
If the video appears zoomed in in an ARSKView, it's most likely because it's frame size is too big in one dimension, and it's essentially trying to do an aspect fill effect, which causes one of the dimensions to zoom in.
Make sure the scene.scaleMode is .resizeFill1. Next, make sure that the ARSKView width / height ratio is exactly the same as the configuration.videoFormat.imageResolution (swap width & height if in portrait mode).
In my case I was using phone in portrait mode and using the back camera. configuration.videoFormat.imageResolution was 1920 x 1440. Since it's in portrait, I jotted down the size as 1440 x 1920 (i.e. I reversed it). Next I calculated the ratio: 1440 / 1920 = 0.75. Thus, on an iPhone 11 which has 414 pixels horizontally, I needed to ensure that the height of the ARSKView was 552. Since 414 / 552 = 0.75.
If my ARSKView height is too small (e.g. 207) this makes the ratio too big (e.g. 414 / 207 = 2). In this case, the entire width of the video will be seen properly, but the top and bottom of the video will be cropped out of frame.
If my ARSKView height is too big (e.g. 828) this makes the ratio too small (e.g. 414 / 828 = 0.5) In this case, I end up with the entire vertical portion of the video seen, but the horizontal portion will be zoomed in to maintain the aspect ratio.
1 The other fill aspect ratios like .fill and .aspectFill might work for your use-case as well, but the one you likely want to avoid at all costs is .aspectFit which behaves very oddly, and never shows you the full video resolution no matter the size of the view. As you resize the ANSKView's height from 0 to larger, you'll notice that it crops both the vertical and horizontal parts of the video, and once you reach 552, it'll stop revealing (never having reached the full video resolution), and instead go into zooming, followed by a weird black bar being added to further cover the vertical dimension. It also has black bars in the vertical and horizontal dimensions nearly the entire time, leading to a poor user experience.