Add a dirt/smudge/scratch map to specular_roughness and maybe a slight bump map too.
I am very glad to see your answer. Please look at the picture below. The inherent colors and highlights are very obvious in the direct sun. The rendering outside the glass is correct, but the rendering effect inside the cockpit is not correct.Thanks.
Thank you very much for your reply. I have added a light below. This should be his correct performance. The highlights and inherent colors are obvious under direct light.Image Caption
Have you tried this scratches osl shader?
https://arnold-rendering.com/2020/03/20/scratches-osl-shader/