Typically, the Fresnel effect causes images to soften around the edge of a reflective surface. So, save a copy of the scene, and then delete all the textures. Make a new texture without activated channels, except for the color channel. Make the color channel 100% white and apply it to each object in the scene. Now remove all the light sources and create one new point light that is in the same place as your camera.
If you animated this scene, you would like to group the lights into the camera if the camera has moved. This light source should have no decay and no shadows and be at full 100% intensity. Run this pass and name it "Fresnel.tif". Now, in order to control the fresnel reflection effect, you should have four separate files from four rendering passes: Mask Pass, 100% Reflection Pass, 0% Reflection Pass and Fresnel Pass.
Composing these passes together can be done in Photoshop or any image editing program that allows multiple layers to be used. However, it's very simple in AfterEffects, and if you are doing animation, AfterEffects is the only way to go. Thus, we will look at the build process in AfterEffects. In AfterEffects, import all four passes into the project (File> Import> Video Files).
After all of them are imported, create a new composition (Composition> New Composition). Do not forget to adjust the size of the composition so that it corresponds to the size of the rendering and the final desired size. In this case, the rendering has a size of 800 x 600 pixels, and since it is fixed, the length should not exceed one frame. In this first composition, we want to start influencing how the fresnel effect plays out.
Drag the 100Reflection.tif file from the Project window to the Composition window or Time Layout window. Then do the same with Fresnel.tif. At the bottom of the “Time Layout” window there is a button labeled “Switches / Modes”. Press this button so that you can see the functions of the mode and tracks of the mat of this composition. Change the 100Reflection.tif mode to “Add” and change the TrkMat setting to “Lum Inverted Matte”.
This means that Fresnel.tif (or our fresnel pass) is opaque for 100% reflection. Lum Inverted Matte determines that the pixels will be opaque when the brightness value is 0%. Notice that the center of the ball is now dark and “aligned” in the composition window. Now we need to mask the effects of the fresnel passage from the rest of the image. To do this, create a new composition (Composition> New Composition) and place “Comp 1” from the “Project” window into the “Composition or Time Layout” window.
Now place the MatteMask.tif in the same way and click the "Switches / Modes" button. This time, change the Comp 1 mode to “Add” and change TrkMat to “Luma Matte”. What it does is use the first composition (the one where the Fresnel passage was applied to 100% reflection) and mask everything except where the ball is treated as defined in the MatteMask.tif transmission method. Create a third composition (Composition> New Composition), and in this composition, first place 0Reflection.tif in the Composition or Temporary Layout window, and then place Comp 2.
This places a clean file with textures and lighting for all the objects below, and then places a bit of the sphere that was modified through the lamination we did in Comp 1 and Comp 2 from above. Click the “Switches / Modes” button and set the “Mode for Comp 2” to “Add”. You can continue to improve the effect by applying a blur effect to the reflection. You want to do this in Comp 2 and apply the effect to Comp.
To do this in the Timeout window, click on the Comp 1 line (and not on the tab), then go to Effects> Blur & Sharpen> Gauss Blur. A new window should appear in the workspace, which will allow you to adjust the degree of this effect. Tune in to your liking, making sure that you click on the Comp 3 tab in the Time Layout window to check the results periodically. When you like what you see in the final Comp 3, go to Composition> Save Frame As> File. This will allow you to save the file as a Photoshop document, which you can later save as jpg, tiff or any format you need.
If it was an animation, you would go to the track> Make Movie. After Effects will then take some time to make the adjustments you made to the frames you imported. You might think, “Well, if I still have to do in AfterEffects, why not just redo it in a 3D application?” In some cases, this may be a more reasonable way; however, in most cases, AfterEffects will generate many frames per minute, rather than one frame in many minutes, as most 3D applications with large, complex files do.
In addition, in some situations like the ones discussed here, we create effects that cannot be easily implemented in a 3D application, so AfterEffects (or Photoshop) is the only way to do this. This is another argument in favor of the fact that he was never too attached to any one program. Use the application or a combination of applications that perform the task to create the desired visual effect.
