How know current camera’s curvature?
Or possible set camera’s curvature, like a Convex lens?
Please master. 
do you mean this? What is Field Curvature?
you can use postprocessing pipelines
Use the default rendering pipeline - Babylon.js Documentation
or simply for use lensrenderingpipeline
Use depth-of-field and other lens effects - Babylon.js Documentation LensRenderingPipeline - Babylon.js Documentation
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Thank you!
I’am found from in your answer! 
This is distortion