Photorealistic Sun Dogs

www.atoptics.co.uk  ©L Cowley & M Schroeder. All rights reserved.

HaloSim3 program found at:

https://www.atoptics.co.uk/halo/downld.htm

If you are interested in the sun's glare but not the sun dogs, check out this mod:

https://www.nexusmods.com/oblivion/mods/49880

For a discussion about why the sun always points a certain direction, see this mod:

https://www.nexusmods.com/oblivion/mods/49879

HaloSim3 is a raytracing program that simulates sun dogs of all types. You can create some fantastic images using the program. I made some basic sun dogs and used GIMP to edit the results to be suitable for in-game use. This produced far higher fidelity and mostly cleaner results than trying to doctor a photo.

Currently the images are somewhat grainy because I'm not familiar with the program and don't want to spent too many hours rendering just yet. The sun was simulated with an inclination of 1 degree above the horizon, so it will look most realistic at absolute sunrise and sunset.

Recommendation: in Oblivion.ini under set:

fSunGlareSize=226. 0000

fSunBaseSize=350. 0000

The sun itself having a textured glare is leading to a very interesting backdrop effect with the clouds, there's a real sense of perspective when the flare is behind the clouds but in front of Masser or Secunda.

Under certain viewing conditions the texture can appear to be distorted, seeming too tall or too wide. I assure you the sun texture is nearly perfectly circular and the sun glare is mirrored so it is 100% symmetrical. This mild viewing distortion seems to be a part of Oblivion's sun rendering. I believe it is due to the sun being rendered as a sprite. This means it is a 2D picture living in a 3D world and it seems to rotate and stretch in an unusual manner compared to the very normal looking 3D terrain.

The dogs were rendered to fit a field-of-view of 120 degrees. This is too large for typical gameplay but if you want to see approximately how large the phenomena looks in real life,  set:

fSunBaseSize=715. 0000

With a normal in-game FOV of 75-90 this is going to make the atoptics seem ABSOLUTELY COLOSSAL. You have to remember that in real-life, our eyes are naturally able to provide an almost 180 degree FOV with a few degrees of precision focus in the center, always scanning. If the sun glare ends up covering 120 degrees of the sky that's still a lot less than what we can easily see with a little looking around, we can "see" the full 360-degree sky dome with our peripheral vision. But in-game we have no peripheral vision and our "viewport" the screen can only show a fraction of the sky at a time. The central ring occurs at exactly 22 degrees of deflection from the Sun so we can easily calculate the exact size the flare n