## What is Lacunarity in Perlin-noise?

Lacunarity. A multiplier that determines how quickly the frequency increases for each successive octave in a Perlin-noise function. The frequency of each successive octave is equal to the product of the previous octave’s frequency and the lacunarity value.

**How does Perlin-noise work?**

Perlin noise is a procedural texture primitive, a type of gradient noise used by visual effects artists to increase the appearance of realism in computer graphics. The function has a pseudo-random appearance, yet all of its visual details are the same size.

**What are Perlin-noise octaves?**

Perlin noise combines multiple functions called ‘octaves’ to produce natural looking surfaces. Each octave adds a layer of detail to the surface. For example: octave 1 could be mountains, octave 2 could be boulders, octave 3 could be the rocks. Lacunarity of less than one means that each octave will get smoother.

### Is Perlin Noise a fractal?

Perlin noise is an algorithm that creates smoothly varying random structures of an arbitrary frequency. Through the use of a technique known as fractal noise or fractional Brownian motion (fBm), octaves of noise with different frequency are combined to generate coherent noise with a broad frequency range.

**Why is Perlin Noise used?**

Perlin noise can be used to generate various effects with natural qualities, such as clouds, landscapes, and patterned textures like marble. Perlin noise has a more organic appearance because it produces a naturally ordered (“smooth”) sequence of pseudo-random numbers.

**What is coherent seismic noise?**

1. n. [Geophysics] Undesirable seismic energy that shows consistent phase from trace to trace, such as ground roll and multiples.

#### What is 3D Perlin noise?

Generates a procedural noise when a baked Position Map is plugged into the input slot. It is meant for use with the GPU engine only. Very similar to Perlin Noise and Gaussian Noise, but instead works in 3D Space, based on the UV coordinates.

**How does a noise module work in libnoise?**

In libnoise, not all noise modules generate coherent noise. Some noise modules modify the output value from another noise module, while others combine the output values from two or more noise modules in various ways.

**How do you create rough terrain in libnoise?**

To generate the rough mountainous terrain, you’ll create a module::RidgedMulti noise module, which generates ridged-multifractal noise. This type of coherent noise is similar to Perlin noise, except it adds “ridges” to the coherent noise.

## How to add seed to Perlin noise in C + +?

Given the same seed value, the same noise values should be generated. If the solution would be to have a custom noise function, I would be interested if it could be implemented using Boost.Random (or C++11’s Standard C++ Library classes).