render volumetric - view 'top' - problem luci

[spilladabalia]

I explain my problem as briefly as possible.
I dissected my model horizontally and rendered from the 'top' view. the result is, practically, that of a plant. in the model I have many stairs and ramps, oriented in various ways and with the lighting that I used (triangular with 3 target spots) the steps lose definition, the trend of the stairs is flat, not well readable (being a plant, clearly I have to play on the shadows).
Do you have any plans?
Thank you so much!

 

[Fulvio Romano]

the top renders will never be good, point.

to make a little something... a "direct" (I don't know how it is said in 3dstudiese, I mean that with all the parallel rays, as to simulate the sunlight) to 30 ° regarding the dominant dimension. . .