Hey Vikkram! Long time no see.

I replicated your settings and I have no idea of what's wrong with your render. In fact, the environment skylight alone set to 2 (direct light turned off) is burning my scene to whites.
The only thing I can think of (so far) is the type in the color mapping. Is it set to the default (linear multiply)?

Beautiful building, btw.

fine anthony. how r u?

caprier, ya i am using default linear multiply only for color mapping but changed dark mapping to 5 as advised google search with topice "vray exteriors rendering dark", otherwise it is even darker than now.i have tried all this settings first on a simple scene with out the materials (followed a tut) and it is fine. i am attaching that here.

my god caprier, i never expected this clue. i never expect this kind of camera effects. really wonderful. its amazing cam very close to the realworld. I just used it because it is there. i don't know anything about it. thanku very much. since how many days you are using this? this is the first time i used that is since 1 day.

ecidream first of all thanks for the detail explanation. coming to answer the qs.

No, i am not using vray sky. only environment light. and there is a sky map in the environment (not vray sky).

yes i am not using vray sun. yes problem is with the camera. i have not noticed that until caprier pointed it. yes i did it already as what suggested using standard camera instead of vraycam. with this i got major difference. the above image is the result of that.

yes environment light is set to 1.0 and very light skyblue color. yes selcted area filter upto i'll now change it. sampling is now set to min -1 and max 1 for quick preview. irrediance map is set to min -4 max -4. color mapping is set to linear map and 1 (defaults). clamp output n subpixels are not selected. now i do this rendering and the redering with settings u specified and i'll post them here side by side.

Comments? Well...

I don't know VRay but here goes...

Your own settings looks a bit blurry as in like a soft-focus. Ecidream's suggestion looks like it's a bright sun shiny day. The third setting looks like it's shot in overcast lighting. I like ecidream's.

Ideas to tweak your setup? I wouldn't know. Heheheh...

However, I believe you may need to change or tweak the colours a bit. That what makes your rendering looks fake. Your test render with white material overide looks like its carved from polistyrene blocks - real, white, polistyrene blocks scaled model - so there's nothing wrong with the Vray setup, I believe.

About the colour being bounced onto other walls, I don't know how to adjust it in Vray but I believe there must be a setting for the number of times the light is bounced off of a surface so you get the realistic GI. Maybe only bounce it once? But I'd try using a darker material/colour first. Tell you what, why not take a photo of a surface that have your desired colour? Or scan it from the paint brochure? Or find out the material's true GI parameters? You know, like how gloss paint has a different reflective surface than plastic surface.

Oh, one last thing: The Ecidream's suggested renders looks a bit bluish. You may photoshop it to 'shif' the colour to just a bit to the red-orange tint so that the ambience looks natural i.e proper white-balancing.. If you're familiar with broadcast equipment, imagine a vectorscope helping you do the colour correction by showing where to shift the chrominence to the desired area so you get proper white balance. I don't know how to explain this white balancing thing properly, anyway. But the render's bluish, make it warmer so that it looks right.

All in all, you did a great job!