Just wow!

@chris fullmer said:

In SketchUp you'll see that those faces that are extra dark are in a shadow from the sun. Try this, turn off shadows and turn on "Use Sun for Shading". You see you get a smooth shading, but no hard shadow lines. I know that doesn't help with V-Ray though.

Maybe in v-ray do something to help diffuse your sunlight. I'm not sure how V-Ray works, but can you make you sun physically larger? I think it would help if you didn't have a small point of light casting the shadows, but if you had instead a large light that would create softer shadows. That might be something to try.

Thank you very much for bringing me to a couple of ideas!
1.Increase the size of the sun (1 to 24):

2. Do not use the sunlight at all. I tried a rectalgular light instead:
   

I think I shall not use sunlight with this model.
And thanks to all for suggestions!

@chris fullmer said:

What software are you using to render with?

V-Ray 1.49.02

@gilles said:

its just something to see with shadows, if you change a little the hour or the month everything goes ok.

@unknownuser said:

yeah.. thats the way the flat surfaces are shading (you can't have a truly gradual shade on a curved object being represented by flat facets.. not inside of sketchup itself..)

here's your model with the sun position changed.. now you have 'problem' polygons in other locations.. see?

[attachment=0:1f7woi5z]<!-- ia0 -->zil_debug.skp<!-- ia0 -->[/attachment:1f7woi5z]

[edit- yeah.. what gilles is saying]

Now i understand. I made a render with another sun position and yes, hard edges appeared in the some new positions. And how it can be avoided? I need to make more hi-poly model?

@gilles said:

its just something to see with shadows, if you change a little the hour or the month everything goes ok.

Do you think so? They look very hard-edged on a render. I don't like it at all ))

@chris fullmer said:

I think Dave's got some good intuition on that - . Could you upload the model?

Allright, here it is:

zil_debug.zip

@dave r said:

It's hard to tell without seeing the SKP file but it looks to me as if either those edges are hidden instead of softened and/or there are internal faces connected to those edges.

Here is closeup view of the top-right poly.

I manually deleted all 3 lines, then made them again with "Line" tool, and erased with Ctrl pressed. Nothing changed. This put me into a dead end.

Dear all, I need your help. Why some polygons/edges in this model look like this?

@beginner said:

Folder with SKP files looks different too

And "Open" dialog too, with "giant" preview

Guys, you are exaggerating ) This is my first big SketchUp job, and it has been going on for almost a year. When i started, i knew nothing about plugins, rendering and many other stuff.
PS: just made ​​another render, and see that there is still a lot of improvements to do. Thahks you all for your advice and criticism