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Terrain smoothing algorithm

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#1 xDarkShadowKnightx   Members   -  Reputation: 374

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Posted 24 August 2014 - 08:08 PM

Hello! I'm creating a terrain/heightmap editor and am wondering what the typical "Smooth Terrain" tools algorithm would be. I'm currently using the Box Filter algorithm (take the surrounding heightmap pixels and average them together to get a final height). But this doesn't produce satisfying results, nor does it look like what Unity3d's terrain smoothing tool produces (Unity3d being an example of what I'm looking for). Does anyone have any ideas as to what Unity or other terrain editors use for there smoothing tool? Thank you!



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#2 xbattlestation   Members   -  Reputation: 320

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Posted 24 August 2014 - 09:06 PM

Increase the size of the box?  Sorry I don't know unity, but I'm pretty sure if you set each heightpoint to the height of the average in a large box instead of the average neighbour's height, then you should see a more dramatic effect?


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#3 Ashaman73   Crossbones+   -  Reputation: 7235

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Posted 24 August 2014 - 10:44 PM

Use gaussian blur (the heighmap is just a grey-colored greyscale image).


Edited by Ashaman73, 24 August 2014 - 11:56 PM.


#4 TheChubu   Crossbones+   -  Reputation: 4187

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Posted 24 August 2014 - 11:52 PM


the heighmap is just a grey-colored image
HOW DARE YOU

 

:P

 

More seriously, Ashaman is right. What you can further take from his statement is that a heightmap can be treated like any single channel image, thus you can use whatever image filter you want on it (blurs, distortions, noise, low pass, high pass, etc).


"I AM ZE EMPRAH OPENGL 3.3 THE CORE, I DEMAND FROM THEE ZE SHADERZ AND MATRIXEZ"

 

My journals: dustArtemis ECS framework and Making a Terrain Generator


#5 xDarkShadowKnightx   Members   -  Reputation: 374

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Posted 25 August 2014 - 10:47 AM

Alright I'll go ahead and will try both increasing the box size and the new filter. Thanks guys! I'll make sure to get back to you as soon as the changes have been done.



#6 Alundra   Members   -  Reputation: 853

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Posted 30 August 2014 - 02:42 PM

Here the code I use to smooth a part of the terrain or the whole heightmap when I import from an image :

float CTerrain::Average( const Int32 i, const Int32 j ) const
{
  float avg = 0.0f;
  float num = 0.0f;
  for( Int32 m = i - 1; m <= i + 1; ++m )
  {
    for( Int32 n = j - 1; n <= j + 1; ++n )
    {
      if( InBounds( m, n ) )
      {
        avg += m_Heightmap[ ( m * m_InitInfo.Width ) + n ];
        ++num;
      }
    }
  }
  return avg / num;
}

Is it really better to use a gaussian filter ?







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