For my final project, I created a new light source for lrt to model lighting due to the sun. My SkyLight model is parameterized by the latitude and longitude of the viewing location, the time zone of the location, the time of day, the day of year, and weather conditions.

 

My project is based on the 1999 SIGGRAPH paper by A. J. Preetham, Peter Shirley, and Brian Smits at the University of Utah.

 

The paper can be found here.

 

 

◄ This image was produced by my implementation.

 

 

 

 

 

Sunset:

 

  

 

 

 

6:30 PM - May 25th

 

Latitude: 38

Longitude: 75

(Approximately Washington, DC)

 

Turbidity: 2

 

 

 

 

 

 

           

 

 

 

7:00 pm -May 25th

 

Latitude: 38

Longitude: 75

(Approximately Washington, DC)

 

Turbidity: 2

 

 

 

 

 

 

  

 

 

7:30 pm – may 25th

 

Latitude: 38

Longitude: 75

(Approximately Washington, DC)

 

Turbidity: 2

 

 

 

 

 

 

 

Objects:

 

 

       

 

               

 

 

 

 

 

 

 

◄Here is a black and white rendering of the sky scene. This is based only on the luminance value values at each pixel. The model behaves appropriately, lightening towards the horizon.

 

 

 

 

 

Alternative Renderings:

In the process of modeling a realistic sky scene, I came across quite a few unexplained phenomena. I am convinced that these results are of no fault of my own, and therefore their existence can only be explained as ‘magic.’ The following is my explanations of these peculiar results.

 

           

 

 

 

◄This picture appears to be a image of the sky in the distance with a road in the foreground.

 

 

 

 

 

 

            ◄This is a rendering prior at 6am, prior to dawn.

 

 

 

Alter Reality Sky Models:

This category of ‘magical’ images could possibly represent the appearance of the sky in an alternate universe.

 

 

 

◄ This is how the early morning sky would look if it were green.

 

 

 

 

           

 

◄ This image represents how the sky might look to a person on a planet with a red atmosphere, such as Mars.

 

 

 

 

           

 

◄ This image shows how the sky might look on a planet with a pink atmosphere.

 

 

 

 

 

           

 

◄ Here is a green atmosphere.

 

 

 

 

 

           

 

◄ Here is the green atmosphere again on a brighter day.

 

 

 

 

 

 

◄ Clearly large explosion of some sort must have occurred during the rendering of this picture. The red along the bottom of the image must be lava

 

 

 

 

 

 

           

 

◄ Here is a picture several days after the explosion; the molten lava above has solidified into yellow sand.

 

 

 

 

 

 

Modernistic Sky Models:

This category of images does an excellent job at portraying how a modern artist might depict the sky.

 

 

                    

 

                       

 

                             

 

                        

 

Kristen Neal - kgn4b@virginia.edu