Houdini Workshop - Weeks 1-4

    These are all of my notes from the first two Houdini Workshop days. I will continue uploading my notes as the workshop continues. These weeks continued to iterate over the island project.

    One of the things discussed in the workshop is the idea of levels of noise. If you want something to be realistic in VFX, you need 3 levels of noise to make it believable. Big, medium, and then small, with the amplitude of the noise getting smaller as you go through each level.

    Voxels were also discussed, you can think of them as 3D Pixels.

Starting out

    First  we need a curve node to draw the outline of the island. The curve node is a similar tool to Photoshop's pen tool. Once the curve is complete, we need to change the normals, as they are currently facing down away from us. Make a reverse node to show the Normals right side up. If we don't do this step it wouldn't render correctly. Finally, add a polyExtrude node to give it some depth. 

Making Volcanos

    We're starting to make a rough outline of our island. Now we want to add in mountains and volcanos using cylinders. Create a cylinder node. and adjust the top radius so the bottom radius is larger. Then use a transform node to adjust the position and size. Duplicate this with how many volcanos/mountains you want. 

Change the first input box for radius to change the top radius

    Once you've finished making enough mountains, you'll need to combine them all, including your island shape into a Merge node. 

Should look like this for now

Heightfield Node

  

    Now drop in a heightfield node, make it large like 4,000 by 4,000. Heightfields are useful in making realistic terrains. Using a heightfield projection node we can use the geometry we just made to 'shrink wrap the heightfield's volume around it. The heightfield uses voxels instead of polygons, so it'll appear smoother.

    You'll want to have the heightfield in the first input slot, and the merge node in the second input. 

    We have the heightfield set up, and we can use different nodes Houdini already has dedicated to manipulate heightfields to get a realistic looking Terrain. However, we first want to create a mask so the noise doesn't affect the water around the island. 

Heightfield Mask by Geometry

    You need a Heightfield mask by geometry node. First connect the heightfield project node to the first input, then connect the merge node you have with all the volcanos and poly extrude. You shouldn't have to change anything in the parameters. In the viewport you should see your island show up red. Anything in red is what will be affected. Everything outside the red will be masked out. 

    We'll want to adjust the mask so it fades off as it goes into the water. Add a mask shrink node and change the radius to around 50. Then add a heightfield mask blur node and change the radius to around 100. 

    The mask is now finished and we can now move onto adding noise to the terrain. 

Adding Noise

    We can consider the base island shape and the cylinders to be our first level of noise. They're for blocking out the overall shape. Now we'll start on our second level of noise with a Height Field Noise Node. 

        Insert the heightfield project node into the first input of the heightfield noise node, with the second input coming from the mask we just made. Change the parameters to: 

• Noise Type: Worley Cellular F2-F1
• Amplitude: 200
• Element size: 810 (this is the scale of the noise)
• Turn off "center noise: (noise is actually 4 dimensions of numbers, center noise means the noise starts in the center of the scene, aka the origin) 

Additional Resources

https://www.youtube.com/watch?v=Oe0_C14lYgU