This is a crude tutorial on how to create a realistic water reflection with a displacement map, like I did in my "Tent On The Water" chop.
For those who don't know: A displacement map (dmap) "shifts pixels" in horizontal and/or vertical direction according to its brightness values. White shifts pixels one way, black shifts the other way and 50% gray does nothing. I used a single channel dmap. A dmap can also have two channels, one for each direction.
First make the dmap. In CS use 'Filter > Render > Fibers...' Use the sliders to control the size of the waves and hit OK. Rotate the image 90 degrees.
Zoom out. With 'Free Transform' create some perspective by Shift+Ctrl+Alt / Shift+Command+Option dragging one of the bottom corners to the side to 700%. Save as .psd.
You can also make a good dmap with the Clouds Filter. Start with a canvas of about 1000px wide and 10000px high. Use 'Filter > Render > Clouds'. Shrink the canvas height to 5%. And then continue as I described above after
.
To create the water, first create the reflections, which is often not as easy as 'Edit > Transform > Flip Vertical'. (Only if it's distant, like the sky or if you're going to use a lot of distortion.)
Merge your reflections into one layer. Select your reflections. The dmap will fit the area confined by the selection. For the right perspective, choose your selection so that the horizon of the dmap corresponds with the horizon of the scene, even if your water surface does not extend to the horizon.
Go to 'Filter > Distort > Displace…'. Set the amount of distortion with 'Vertical Scale'. Set 'Horizontal Scale' (close) to zero. Choose 'Stretch To Fit' and 'Repeat Edge Pixels'. Hit OK and choose your dmap.
In the distance the waves become too small for the pixels. Use a bit of vertical motion blur near the horizon to simulate those.
As a finishing touch to make the wave fronts a little darker, add the dmap as a layer, choose multiply mode, invert, and add a gradient layer mask to darken only the nearby waves.
If you use a lot of distortion, paint a little with 50% gray in the dmap to make sure the reflections connect with the corresponding objects. You will also have to crop away the repeated edge pixels, so extend the reflection layer beyond the boundaries of the final image.
I hope this makes sense.
I'm still experimenting with this. I welcome any ideas to improve this technique.
