DEM file produces different results depending on frame size?

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  07 July 2010
Thumbs down DEM file produces different results depending on frame size?

Hi,

I have used a DEM(Digital elevation model) to create a displacement map.
Essentially this is just a gradient grey scale .jpeg. The file is plugged into the displacement
attribute of my shader set up.

I have been working with a 640x480 sized test render window and positioned all my other elements according to the results defined by this frame size. I have also created a stand in poly as a reference with a simple convert displacement to poly.

However, I am ready to start remdering some full HD720 frames and the resulting displacement in the render is different. Areas where I have purposely painted depressions in the landscape are not a severe and my stand in geometry no longer fits within the scene.

My question is, how do I ensure the displacement maps are tesselating according to my setup. It is only to do with the render frame size. My stand in polygon terrain surface reacts normally.

Do texture files re_size or their aspect re_size if I render HD720. I know 640x480 is 1.333 and HD720 is 1.777 and have tried maintaining the 1.333 size.

I am a little confused as to what might be happening and can only hope someone who has played with displacement maps may have encountered the same issue.

640/480result


HD720 result



regards

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Last edited by aroestenburg : 07 July 2010 at 01:27 AM.
 
  07 July 2010
Hello all,

I have found a related fix. the initial sample rate and extra sample rate needed to be bumped up to accomodate the larger frame size.

If anyone know WHY this is the case , it would be great to know.

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  07 July 2010
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