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doctorsixstring

Unity Perlin Noise: Value Range

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I'm looking for confirmation on the appropriate range of values my Perlin Noise module should be generating. I've written a test that runs my noise generator thousands of times, and stores the minimum and maximum values. A single octave of one-dimensional noise with a frequency of 1.0 and an amplitude of 1.0 results in a range of values between -0.5 and 0.5, but not including either (the exact result of one test was -0.4923 and 0.4981). That seems to make sense, since that range almost equals the amplitude. My limited math abilities recognize that the amplitude is the limit of the range. Increasing frequency to 2.0 and decreasing amplitude to 0.5 results in values between, but not including, -0.25 and 0.25. Again, that matches the amplitude. Next, I generate a set of summed noise values using both the octaves described above. I would expect the final values to be in the range of -0.75 and 0.75. However, running the generator 10000 times results in values between -0.6007 and 0.5991, which is a range of 1.1999. I would expect the range to approach 1.5. Am I misunderstanding how that works, or is there just a low probability of reaching those high values? Do I need to run the generator many more times in order to see values between -0.75 and 0.75?

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The ranges are correct, The reason you aren't seeing the full range when you add them is because this would require both the noise functions to generate the maximum/minimum value at the same point which is a lot less likely then just one of them generating it.

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