About Houdini terrains workflow, notes on masterclass

Massing model

Houdini’s terrain workflow starts with the concept of creating a first pass of blocking geometry, usually with larger required features to create a solid base HF to perform erosion simulations later on.

Techniques :

  • Paint “ HF-paint” Mask painting and distortion
  • Big geometry – large features
  • Lidar Data –
  • Gis Data –
  • 2D images with COPS
  • Geometry Projection
  • Mapbox

Note : HF tools work on a 1k by 1k model as default. Erosion setting are defaulted to this size. this generates larger that realistic erosion on terrains that are smaller than 1k, for this reason erosion settings must be tweaked to accommodate smaller Height Fields

Basic Workflow

  • Basic geometry can be used as a mask – use “ HF Mask by Object
  • HF Paint ” creates a mask by brush painting or can use use a object.
  • “HF Noise Distort” Uses noise to distort masked areas
  • “HF Blur” can blur the HF mask or the HF itself
  • HF layer ” This node composites the height field layers in the first (“base”) input with the layers in the second (“layer”) input. The third input takes an optional mask. A layer can be distorted with “HF noise”works much like photoshop layer it can stack noises of mask of top of each other
  • ” HF project “can bring in geometry files to project into or out from the HF
  • ” A COP Net “ 2D shapes can be brought in from COPS and layered to create a Massing Elevation map. Note H-17.5 can read density from COPS layers
  •  

Seeding

Refers to the process of taking the initial massing model and work in “seeds of interest” with basic erosion passes first at low res, then adding more areas of interest ” lobing” to create obstacles and a extra pass of low frequency Masses this should be Very low res. The general idea is to introduce areas where detail will appear when erosion simulation is generated

Basic Workflow

  • HF – paint layer – Use this node to create new seed areas
  • HF mask by feature – Computed with elevation, it uses the HF own terrain feature to create mask. Use it to produce natural looking masks
  • HF Distort by noise – Use noise to displace the new seeds and introduce a first level of variance
  • HF layer Distort – Uses a mask + HF noise to distort the seeds
  • HF Pattern – creates a nature based pattern for massing of re seeding
  • HF mask clear – clears the current mask
  • HF Terrace – creates terraces from elevations
  • HF mask blur – blurs current mask, very useful for blending between noises

Remap

Process of squashing layers of detail to extract further high frequency detail. Imagine an ancient mountain in which you can see multiple layers of detailed erosion, this happened over millennia ” remapping ” elevation and squashing it helps create this illusion

  • HF remap : remaps elevation to a set parameter squashing detail to begin the the “lobing” process

Lobing

 ” packs of low masses “- refers to the creation of at least two levels of terrains that create lobes of interest by squashing elevation down and adding more detailed terrain features.

Basic Workflow

  • Uses a low res “HF resample” and a “HF remap” to achieve a first layer of lobes
  • HF remap – use several remaps to create more complex terrains
  • Use a low pass of HF erosion or a single erosion type ( thermal or hydro ) ! important”
  • HF erode thermal – a base single thermal erosion node can help create big changes at this point 
  • HD erode Hydro – a base single hydro erosion node can help create big changes at this point
  • Repeat the process until ready to “ Up-res” 

Up- Res –  

Process of Up sampling resolution to generate more detail  

Basic Workflow

  • HF resample – Sets a desired resolution for the final HF
  • Clear masks and create new ones for further shaping    
  • re-Shaping – HF Noise, HF Distort by layer – Create medium detail based on masked parts of the Lobbed terrain

Re seed – Refers to the process of masking different parts of the terrain and re shaping it with the “ Seeding steps” at a higher resolution + An erosion pass. 
Erosion – At low resolutions changes must be made to make erosion more apparent Default is set to work on high frequency detail 


Parameters for low resolution erosion after Re-Seed
Thermal erosion settings

Ramp up Iterations = “how many cycles it takes for erosion to kick in” if 0 = very fast and 1 = slower

Initial factor “Where erosion begins” if at 0.2 of Slope factor == maximum angle factor erosion will work on = 0 = or all will be eroded, Increment of 0.2 for less slope factor

Sediment capacity – “how much sediment can stack up – can be over-cranked to 20 -40 “

Post-process and scatter

Slope Node – Post process node – uses a mask to create mud slide effects
Hierarchical weights scattering: For this to work @weight must be class primitive 
Hf scatter – Can be set to keep incoming points and  Per point count using Source Points this will scatter around  the incoming points. @weight can also be added here. Smaller and Smaller detail can be added to the terrain, lowering the size of each scattered points recursively
Randomize yaw : randomizes rotation of the instances cz3