Hi Denis, welcome
Heh, photorealism is the holy grail - to be fair I've never managed it myself, but an approximation is often good enough for what I need.
A lot of it comes down to the quality of the model and the texturing. If you have a rubbish model, then it will never look quite right, and no amount of awesome texture work will save it. So you need to start off with trees that look like trees and cars that look like cars - theres some fantastic models on the 3D warehouse for Sketchup so take a look and try some of those in your scene.
Next up is how you texture your model - you need to make the surfaces react as they do in real life, so your car needs to be shiny, your grass standing up and so on and so on.
That grass texture - I've never been able to work that one out either, it always just renders completely flat, so if anyone can shed any light on this! A good easy way to make grass:
-Pick a default Sketchup grass texture, example Juniper
-Right click the texture in your model and under the menu heading SKindigo, click edit material to open the material editor.
-You need to add a displacement map to the material (to make it stand up) so under material attributes (click the UI button if you can't see it) and displace, change it from 'none' to 'Sketchup', then enter a value of maybe 0.1.
- Render and your grass should be standing up
For your car, you want the paint to be shiny, so again, right click the texture on the model and in the material editor choose PRESETS and in there is a shiny car paint texture. Click that and now your car should render shiny.
Of course a shiny car won't look shiny without some bits and bobs to reflect in it, so perhaps a fence of some other items in the scene - dress it up a bit really.
Don't forget you need you textures at the correct scale, so right click the textures on the model and select texture, then position to scale and move them around.
The lighting is important too, so you need to fiddle with the shadows and where they fall to make a more dynamic image.
And one last thing, Reinhard tonemapping (the default for indigo) is fine for testing, but try switching to camera tonemapping as you render and try some of the settings. Better contrast always improves the image.
Heres something I did a while ago when I was trying to work out how to use the materials - not photorealistic by any means, but it gives an indication.
Good luck with it all, post your images as you go
