Fix view-space depth for POM (again)

Assets/ScriptableRenderPipeline/HDRenderPipeline/Material/Lit/LitData.hlsl

 #if defined(_HEIGHTMAP)
     maxDisplacement = _HeightAmplitude;
 #endif
-    return maxDisplacement;
+    // TODO: explain this 0.5 factor. It is likely related to the fact that
+    // setting the amplitude to 2 in the UI only results in the max. displacement of 1.
+    return 0.5 * maxDisplacement;
 }
 
 // Return the minimun uv size for all layers including triplanar
 #endif
 #endif
 
-    return maxDisplacement;
+    // TODO: explain this 0.5 factor. It is likely related to the fact that
+    // setting the amplitude to 2 in the UI only results in the max. displacement of 1.
+    return 0.5 * maxDisplacement;
 }
 
 // Return the minimun uv size for all layers including triplanar

Assets/ScriptableRenderPipeline/ShaderLibrary/PerPixelDisplacement.hlsl

 // ref: https://www.gamedev.net/resources/_/technical/graphics-programming-and-theory/a-closer-look-at-parallax-occlusion-mapping-r3262
 float2 ParallaxOcclusionMapping(float lod, float lodThreshold, int numSteps, float3 viewDirTS, float maxHeight, PerPixelHeightDisplacementParam ppdParam, out float outHeight)
 {
-    // TEMP: 0.1 to achieve parity between tessellation and POM w.r.t. height for a single tile.
-    // TODO: for tiling, the max. height of the tessellated height map should be reduced by NumTiles.
-    maxHeight *= 0.1;
+    // TEMP: 1/5 to achieve parity between tessellation and POM w.r.t. height for a single tile.
+    // TODO: explain this factor. Is there a connection with the number of samples?
+    maxHeight *= 0.2;
 
     // Convention: 1.0 is top, 0.0 is bottom - POM is always inward, no extrusion
     float stepSize = 1.0 / (float)numSteps;