@majid said:

also an small tip about those 2d trees of sketchup (i.e like ths one : http://sketchup.google.com/3dwarehouse/details?mid=225cd184c144ad3189319f015ffd8b7&prevstart=0) :to achieving shadows for trees , for sure, you must have those trees above the ground. i.e 2m (or more, to preventing intersection with cars, like the first image) above the ground level. and delete the shadow part from your model.

That is exactly what i do, Majid.
See the attached component.
2D-Shrub01.skp
2/components nested within one, 2D elevation component casts and receive shadows. The 2D Plan component cast shadows but does not receive shadows.
Both 2D elevation and 2D plan components is set 600mm above the ground plan and is on a unique layer. This is done so when in plan view the elevation component can be switched off. [and visa versa for elevation view]
There are three layers;
Master layer for Landscaping - LANDSC
Layer for 2D elevation component - LANDSC-Elev
Layer for 2D Plan component - LANDSC-Plan

Finally, both components have materials that are minimum of 70% opacity. That way they both cast shadows.....

The blue color would be back faces, to correct this select all, right-click and choose 'reverse faces'. As for the zoomed out view, did you ticked the 'override viewport' checkbox in the output section of the vrayfsu options? If you did, uncheck it. Sometimes that worked