Camera FOV framerate issues

I would expect the framerate to go down as FOV increases since you’re rendering more on the screen but I’ve made a simple zoom lens for drone cameras in my game that are supposed to go up to 30x and I can’t get the FOV that low before hitting 12fps. Its a pretty linear scale, too. I get 60fps at FOV 90, 30fps at FOV 45 and so on.

Does anyone have any advice at all on how I can save frames with these extreme zoom levels? My client is asking for realistic zoom capabilities.

What’s the widest FOV ? You’re showing fps going down with narrowing FOV? (60 @ FOV 90, 30 fps @ FOV 45?)
Have you tested just with a fixed camera directly?

The range is 90 to 3, I would need to get as low as 7, which is currently getting around 18fps. How do you mean fixed camera? As in moving the camera? I’ve tried it but if you’re looking at an angle the image barely changes vs looking at the ground directly beneath the drone where you can almost hit the floor. I would need to continuously move the camera based on your viewing angle which might be hard to make realistic.

I started removing things from my scene until I found that the issue was coming from the Cesium World Tiles. No idea what about them is causing it, but will update if I ever solve this.

It was the Frustum culling settings. Ideally you have this enabled but there are some tiles that I was using for an overhead view camera that needed this to be set to false. Then there’s a setting being used when its false called “Culled Screen Space Error” which I had set to 64 because that’s the default. Increasing this to 512 has resolved the framerate issue but some image downgrading now occurs on tiles outside the field of view. I tried out changing the Culled Screen Space Error at runtime as the player zooms in and for whatever reason when doing it like this I maintain framerate while zoomed in and do not lose quality even while zoomed. Alls well that ends well I suppose.