Loss of Render Quality at Bottom Edge

[AstroStudio]

Here's a rather curious case.   The bottom edge of this finished rendered scene (see attached) exhibits a loss of quality.  It seems that I am able to work around the problem by elongating the Camera film aperture and the Render image height by the same proportion.  The glitch will then appear further down, and I can crop out my original scene from the elongated image.  But if anyone has any idea about how to I might ensure an entirely smooth render in the first place, it would be a time-saver.

Some misc notes:  Camera focal length = 15mm.   Image width/height aspect ratio = 0.75

Content makes use of "Dirt and Soil Pack by RArcher" (http://www.nwdanet.com/buy/7-preset-packs/29-dirt-and-soil-pack-by-rarcher)

[Tangled-Universe]

I'm pretty sure this has to do with subdivision of reflected surfaces which are outside the camera frustum.
If surfaces are outside the camera frustum they are subdivided less as an optimization, however, these less subdivided surfaces are being reflected inside the camera frustum and thus look facetted.
What we need is to have TG2 subdivide surfaces outside the camera frustum so that they appear correctly in the render.

In the rendersettings panel go to the advanced tab and set the "ray detail region" mode to "detail in camera".
Then set the ray detail region to 1.
This setting will extend the region of calculated subdivisions of surfaces to 9x the size of the camera frustum.

(1 = 100%, so 100% extra on left, right, bottom, top and left/right bottom/top = 9x bigger with original camera frustum centred.
0.5 = 50% extra added frustum.)

[Tangled-Universe]

Did it work?

[AstroStudio]

Sorry about keeping you in suspense.  I needed to finish a render-in-progress (still running at my bedtime) before I could test your solution.

Now I can tell you that the answer is: YES!  You were dead right.  Extending the Ray detail region did the trick.  Thanks for your help!

P.S., I'm very impressed with your image gallery and with NWDA products.  Cheers!

[Tangled-Universe]

Ghehe, no suspense, just curious
I'm glad I could be of any help and thanks for the nice compliments!

Cheers,
Martin