Good morning. It was possible to improve the material with angrypigs hints. Thank you for that. I had to rework the rivets. They are smaller and dont have deformations at the borders.
My material setup is now the following:
"name" : "Metal_001",
"diffuse" : "163,163,163,255",
"Ax" : "100",
"Ay" : "7",
"m" : "255",
"tex_diffuse" : "metal_diff.dds",
"tex_normal" : "metal_nrm.dds",
"tex_env" : "metal_env.dds",
"tex_opacity" : "",
"tex_reflectance" : "metal_ref.dds"
For faking the metallish illusion i cannot take 200 for Ax. This would be result in a chromium like appearance. Setting it to 100 gives some good results. Which you can see here:
Just the color of the reflection is not as i expected. I made it yellowish, but it just reflects the sun. So its white over the day and goldish at dusk and dawn. I read somewhere, that the color of the reflectionmap controls the color of the reflection, if someone doesnt want the normal sun reflection color. So i guess, i could make my reflection map even grey and the result would be similar.