Design Statement:

Our project is designed to imitate the planetary motion in solar system in GIMP (a software used to generate images). We coded to create images corresponding to elements in the solar system including the sun, the galaxy and nine planets.

We first set the background of the whole image to incorporate galaxy. The background, filled with gradually blended dark colors and intended to mirror the color of the universe, is dotted by hundreds of “stars” from the bottom left to the upper right. At the center of the image lies the sun, around which are nine main planets. The warm color of the background and cool color of stars are well organized into a harmonious composition, which is the picture plane of the whole design. The positive space in the image are the shapes that represent planets and the sun, while the negative space in the back enables us to create the galaxy, which is also the background of the whole image. 

Our project takes various inputs, and we will see the different positions and different colors of the planets in subtly variant background. The orbital periods of nine planets strictly follow the actual ratios in astronomy. Namely, the orbital period of Saturn is 29.5 times orbital period of Earth, and our project accurately reflects this ratio. However, we changed the ratios of distance and radius because otherwise some elements will be too small to recognize in the image. We tried to make the proportion and scale of planets as close to the real ratio as possible. 
We changed the ratios for distance and radius but still intended to keep them within reasonable range and order. Since the sizes of all the elements are relative to the height and width of the whole image, the scale and the placement of all the elements are consistent. We re expecting to display the image of how the positions of nine planets vary with time

The colors of nine planets gradually change among the specific color scheme. As an example, the color of nine planets varies among darkgreen, darkolivegreen, darkseagreen. etc. The similarity shared by the colors belonging to one color scheme adds to consistence of the image. When given distinct reasonable input, the program is supposed to generate images with colors among another color scheme. Meanwhile, we set a light halo around each planet aimed to imitate each planet’s atmosphere. 




Technique Statement:

Our project is based mainly on the following algorithmic tech: Drawing with GIMP tools, drawing with turtle graphic instructions and building images by iterating over positions. In addition, we also exploit truncate and module to create lists of shapes and colors

First, in creating the background for the whole image, we took advantage of “image-compute” procedures. With various input n, the background color will gradually change from black to a mixture of red and blue. We wrapped n around 32 so that each time we will get different background colors, which sum up to 32 possibilities correspondingly.

Second, we dot all the stars on the background with the help of turtle graphic instructions. First we write the procedure to create a pentagon; however, we put down the brush every time the turtle made a turn and let it move forward 1 unit before lifting the turtle up. Through this procedure, we can only display five dots after finishing a complete pentagon. We created the galaxy-like background by drawing hundreds or even thousands (depending on input n) pentagons by using “for-each” command. We are inspired by the procedure “polygonal progression” from Exam 3 Problem 5. We revised the procedure so that the starting points of those pentagons expand from the bottom left to the upper right. We deleted the dots that may form an apparent pattern in order to make the stars look randomly plotted.

Then, we used GIMP tools to create a procedure, “draw-ellipse!” for drawing ellipse (circles). We applied this procedure through “for-each” so that we can draw the sun and nine planets. The distances between planets and the sizes of each planet remain the same, while the position of planets varies with different input n. We wrapped n around 360 as we set a complete revolution of the earth as one unit, and the speed of other planets are all proportional to the speed of the earth. We set the rotational speed as 3.6 degree for 1 unit of input n of earth revolution as 360/3.6= 100 possibilities

The color varies as well. We use “context-list-colors” to extract all the possible colors for one color scheme, and made these color into a cycle list of ten elements (inspired by Exam 2 Problem 5). When input n is in different ranges, the planets will be painted by one of 10 color schemes. 

With above factors being said, we have proved that our project will finally generate 32 background colors, 100 positions for planets and 10 color schemes for planets. This ensures us that we will theoretically have 32,000 distinct images in all. Since the background color does not vary greatly. Even though the background color does not vary drastically, we can still say we have at least 1000 possible images.


Representative values
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