Les didacticiels de LinuxGraphic.org

Blender : Modelling with cross sections
By Olivier Saraja

S t e p 7 :

This step is critical to make the reflection of the lake match perfectly to the reality !

Respectively in front view (NUM1-KEY) and in top view (NUM7-KEY), you should get a location for the Empty related to the camera near than this one :

Now that the pre-requisites are over, let's see the fundamental step, which is very easy.

Select the plane and edit its material properties (F5-KEY) (Material Buttons). Add a new material and call it Lake (MA:Lake). Edit its textures (F6-KEY) (Texture Buttons).
In the first channel, add a texture called Reflects (TE:Reflects). Click on EnvMap and specify Empty in the Ob button Ob:Empty). At the Don't render layer section, select the layer on which the plane is placed (for instance, the third).In the second channel, add a texture called Wave (TE:Wave). Click on Stucci.
Go back in the material properties (F5-KEY) (Material Buttons). Select the channel Reflects. Activate the Refl, Col, Csp and Cmir Buttons. Give the Col slider a value of 0.6 (or any other that suits you).
Select the Wave channel. Deactivate the Col Button and activate the Nor Buttons. Set SizeX to 1.000 and SizeY to 5.000. Play with the Nor Slider if you want to intensify the wave effect, 1.000 being a good starting value.
Set the lake's Alpha to 0.9 and activate the ZTransp Button.