Good idea, I gave this a try (typical vanilla DF, the haystacks disappeared when I re-loaded the save game for unknown reason) with the following results:
- vanilla DF, corrected to 4:3
- daggerfall-ARC.png (86.98 KiB) Viewed 448 times
- DFU, 16:10 cropped to 4:3
- DFU-crop.png (394.11 KiB) Viewed 448 times
- vanilla DF, 1:1 pixel ratio
- df-noarc.png (30.54 KiB) Viewed 448 times
You can notice that the DOS version is slightly taller, which suggests that the XnGine renderer does some vertical squishing at least of 3D objects if not sprites, to compensate for the 320x200 -> 640x480 stretching that would occur on a contemporary 4:3 CRT display. While DFU apparently renders the world in 1:1 pixel ratio, with the wheel on the cart being more "round" (as far as it can be round with this shape) compared to the DOS screenshot. Conversely, the 1:1 rendering in DOS is wider than DFU.
No wonder then that the 4:3 retro rendering option results in the image that is vertically over-stretched, whereas the 2D interface, inventory and other screens always look correct when compared to original DOS output.