This tutorial is no longer available on the original creator's website, so to ensure it is not lost I am hosting it here. It would be such a shame to loose it.
Creating a Waterfall Animation By Richard Vanlippe
The first step for creating an animated waterfall is to create a still version of the scene. To do that, a duplicate of the terrain was made and where the water was to flow over it the areas were selected and lightened. Animating the waterfall was done last using starting and ending keyframes in the Material Editor for the waterfall and pool. To create the basic terrains, PhotoShop was used but its possible to duplicate all of the following using only Bryce.
Place the Terrain After creating the main terrain, launch Bryce and use it for a terrain in a scene file. Spend all the time you like creating the perspective and layout desired. Resize the terrain as needed - feel free to even stretch it and deform it if you want to. The waterfall that flows over the terrain is simply a copy of whatever terrain you use. Its a good idea to assign a family group and name each terrain for each step. That will be useful later if you need to make changes. Also notice that the scene to the right only has one terrain. A second terrain was used for the upper portion of the waterfall later. Start with one and add as many as you like - the technique is the same for all of them.
Wirefame terrain arranged in scene file
Duplicate the Terrain After creating and placing the terrain in your scene file, the waterfall terrain can be created. Select the terrain and use copy and paste to create an exact duplicate. Assign a new family group to the copied terrain before continuing to avoid confusing the two terrains. Return to PhotoShop to edit the duplicated terrain. If you didn't save the original terrain's grayscale image, you can copy the terrain from within the Terrain Editor and paste the copy into a new document in PhotoShop. If you don't have PhotoShop, or anything similar, you can use Bryce to edit the terrain. The basic idea is to lighten areas in the duplicated terrain where the water is intended to flow. The only "trick" is in applying the correct amount of brightness.
Scene file showing the duplicated wireframe terrain
Edit the Copied Terrain The next step is to edit the copied terrain. The intention is to make the portions which are supposed to have water flowing over them slightly lighter than the original terrain. Before you start, you should save a pict version of the original terrain. The edits you make from now on need to be saved in PhotoShop format since the selections made should be saved with the file. At each step in the process you should save both PhotoShop and pict files. As long as your PhotoShop file contains the original terrain idea, you can always reopen the file later and make new selections or changes as needed. Saving selections along with the primary terrain is the basic process for creating all the remaining terrains. Be sure to save the file early on and not overwrite it later!
Open your previously saved terrain in PhotoShop or copy the terrain from within the Terrain Editor
Define the Waterfall To the right is the original terrain with some selections drawn using the lasso tool in PhotoShop. The selections represent where the water will flow over the terrain. One word of caution for this technique - it doesn't prevent you from creating waterfalls that run downhill - and then back uphill again! You'll have to use your own judgement - and maybe some trial and error - to select the correct areas in your terrain. After you've drawn your selections, you should save the file again - in PhotoShop format - to retain the selections. Although two terrains can effectively create a waterfall, I've actually used three - and its important to be able to restore the saved selections later. Next step is to feather the selection slightly - about 2-4 pixels should do - and then lighten the selection - about +4 to +8. Then, select all and reduce the brightness of the entire terrain by only about -2.
Duplicated terrain with selections drawn with PhotoShop's lasso tool to define the water areas
Check the Waterfall Terrain The reason for selecting the entire image and reducing the brightness by about -2 or so, is to prevent the duplicted terrain from showing through in places where it isn't intended to. In addition, I always do a test render of the edited terrain combined with the original to see how the edits came out. No fancy semi-transparent and reflective materials at this stage though! I assign a bright red material to the edited terrain to see exactly how the edits look. If you aren't quite satisfied with your work - return to PhotoShop or the Terrain Editor and start over. If you make new selections in PhotoShop be sure to save the file again! This is only the first step and those selections become important later. After you've made a test render that shows your edits are placed as you like, you can try a render with a material that looks more like water.
A rendered view of the edited terrain assigned a red material
Basic Water Layer At this stage its hard not to stop and assign a water material to the terrain you've just created. I've done just that and rendered the preview at the right. But wait - the results looks less like a waterfall and more like water runoff! Truth is, although the terrain can be made more noticeable (increase the brightness of the selected areas - and/or reduce the transparency of the assigned material), this is really just the underlying layer for the waterfall that I made. You could probably skip this step but the process involved so far is at the heart of the technique and this terrain combined with one more additional copy is what creates the final affect. Select the original terrain once again and make another copy. Assign the copy to a new family and return to PhotoShop and the terrain you saved with the selections so far. If you are using the Terrain Editor, follow the instructions for the second terrain copy.
A rendered view of the edited terrain assigned a water material
Edit the Second Copy Back in PhotoShop with the original terrain. Load the previously saved selections (I told you they'd be needed again!) and feather the selection by about 8 pixels. Use the "Brightness/Contrast" tool to increase the brightness of this feathered selection by around +18. This the terrain edit will be assigned a material for "water drops". The feathering combined with the increased brightness makes the selected area both wider and higher than the previous copy used for the water material. The feathering will also ensure the selected areas are more rounded. Save a copy of the edited terrain as a pict file or copy and paste the edited terrain directly into the Terrain Editor in Bryce. Next its time for the fun stuff - making this terrain look like rushing water!
Second terrain copy with the previous selections feathered and then brightened by +17
Make Terrain Solid After the second edited terrain copy has been applied to the third copy of your terrain in the scene (I usually name this terrain "water drops"), there is one more step before leaving the Terrain Editor and opening the Material Lab. The water affect that is coming up uses a volume material. While volume materials that are too complex can take forever to render, they really don't have to be complicate to work. While still in the Terrain Editor, locate the pull-down menu at the lower right corner of the preview area and select "Solid". This will make sure the volume material that is applied next actually has a "volume" to work with.
An important step before assigning a volume material to a terrain is to set the terrain to "Solid" in the Terrain Editor. If you don't do that, you'll just be wasting rendering cycles for an affect you won't even see.
"Water Drops" Material The material used for the waterfall scene is provided and available in both zip and binhex format. The extracted file name is "drops.mat". You can skip the following discussion and jump directly to the section about animating the volume material but I've included some information about the material if you are interested.
This is a quick discussion concerning the basic controls for volume materials and no more.
Volume Material Setup The screen shot below shows the basic setup for the volume material used. This isn't particularly fancy. Normally I shy away from setting a full ambient value, for instance, but in this case it ensures that the material appears bright white at all times. If you intend on using this material on something that runs under some shadows, you may have to adjust the ambient level. The lower four sliders - Base Density, Edge Softness, Fuzzy Factor and Quality/Speed - are the ones to play with. It is the combination of all four that deterimines how the final material looks. For this material, I reduced the quality to its lowest to help increase the render time. The fuzzy factor was also set to zero to increase the "sharpness". Edge softness, however, was increased to maximum which allowed each "drop" to be a little softer without blurring the overall affect. The Base Density was adjusted until the affect seemed full but not overwhelming.
Snapshot showing the basic setup of the "water drops" volume material.
3D Texture for Volume The 3D texture uses a single noise operator assigned to the alpha channel. With only one noise operator , the rendering time is much faster. Continuous noise was used to drive the density. Its good for a wide variety of effects and doesn't require as much render time as some of the other noise selections. The frequency and direction will depend greatly on both the terrain's size and orientation. In the final material, I scaled the 3D texture by 200% and the direction was alterred over time for the animation. The octave amount was kept low to keep the alpha channel more distinct and the mode was left as standard.
Noise operator used for the volume value
Filter Settings for Noise One of the more important controls for noise is the filter. This simple little tool can make all the difference when working with even the most basic of noise operators. For the water drops material, the filter was set for "quantize". This changed what would have been a rather "fuzzy" alpha channel into something much more coarse. With only a few steps of grayscale being used (the "C" adjustment"), the gradual changes from black to white in the original noise operator are changed into more distinct jumps. The end result is a random "drop" look that works well for water spray.
Filter settings used to create a more pronounced alpha channel
Final 3D Texture To the right is a snapshot of the final 3D texture assigned for the volume values. The first and last "squares" are empty because those are used for "color" and "bump" respectively - and neither of those values is being used for this material. The next step was to repeat this entire process for the "upper waterfall" terrain in the scene and merge in some trees. After that the materials were set up with keyframes and rendered as a movie. To complete the still waterfall, however, here is a quick look at the scene so far.
Snapshot of the 3D texture used for the volume values
Water Drops Test Render Here is a test render with all three terrains rendered together. The second terrain with the water assigned is almost invisible. You could probably leave it out in many cases. It was included because it seemed to add a subtle affect that was noticeable when rendered larger. As stated above, from this point on the other elements in the scene were added. Actually, the upper terrain had been added earlier but was left out of the screen shots. Its usually easier to compose a scene with the basic terrains before starting the process of duplicating and editing the copies for use as waterfalls. The trees, at any rate, were added at the very end.
A preview render of all three terrains showing the final "water drops" material