Updated June 11, 2011

This is a guide to help you place objects in an exact circle.  I have used these exact steps to place objects in my own maps and I hope they help you.

What Will I Need

Normally when Setting things up you will only need to play Halo.  For this you will need GIMP and a Spreadsheet (recommend using MS Excel, The MS Office Online Tool (can be done in side of web browser), or Openoffice.org if not Excel, they both work the same and the functions I will use will be available in both.

We will start in GIMP

  1. Create a new gimp image by opening up FILE>NEW or CTRL+N
  2. Type in the value
    1. How big you want the Radius of the circle to be, Times by 10, and Times by at least 3 (may be bigger this will give you room to work)
    2. Example If I what a circle of 13 (in the Halo Reach Forge Units). You will need to create a new image of (13*10*3), Which equals 390, but I will use 450 to have some room to work in.
    3. Create a New Image
  3. Select the Ellipse select tool in the toolbox
    1. Ellipse select tool
      The on highlighted in yellow
  4. then click and drag in the picture area and create a circle of any size
    we will make it exact in the next step.
  5. now in the Toolbox window;
    1. *update* turn Antialiasing off by unchecking the box it gives a better line for what we are doing
    2. Set the aspect ratio to 1:1 (for a circle)
    3. Set Size to the DIAMETER of your circle
    4. Last set the position to about 50 or 100 (use the same number for easier math later)
      1. again so you have room to work
    5. Ellipse select Properties
  6. next create another circle but click on Mode: Subtract (the 3rd from left in image above) or hold CTRL while creating a circle.
    1. *Update* Keep Antialiasing off and the Aspect Ratio to fixed “1:1”
    2. Set size to 4 less than the diameter of your circle (260-4 = 256)
    3. Set Position to 2 more than what you did in the previous step (100+2 = 102)
    4. see picture in step 7
  7. Your ellipse should look like this
    1. Ellipse should look like this
  8. Now select the Bucket Fill tool
    Bucket Fill tool
  9. Hold down CTRL and scroll up to zoom in on the existing edge of the circle
  10. Click inside the 2 line of the circle to make the edge permanent
    Bucket Fill Should look like this
  11. Hit CTRL+SHIFT+A to Deselect everything
  12. Select the Paint Brush tool and set the Brush to “Circle (3)”
    Paint Brush tool
  13. now to find the center of the circle: Take 1/2 the diameter + one of the numbers from the position
    1. (260/2)+100 = 230
  14. zoom in and scroll so that the measurements 230 on top and left are visible
  15. Then make sure the the mouse is at perfectly at 230, 230 at the bottom Left corner of the window
    Placing the Center Dot
  16. Stay zoomed in and Select the Measure Tool, Then Click the check box for “Use info window.”
    After that, click somewhere in the image and drag to the center of the dot
    Measure Tool

    1. Note: If you ever loose the measurement “+” in the center of the dot you can come back to this step and re-find the center of the dot
  17. now zoom out so that you see the whole circle
  18. now Grab the “+” that is NOT in the center of the circle and drag it close to the top of the circle
  19. Zoom in to where you are at the top of the circle and can start to see the pixels
    I found 800% to be best
  20. Click and hold on the measurement “+”, hold down CTRL on the keyboard, then drag to the top of the circle and to the edge of the very top pixel.
    1. The Reason for Clicking and holding first then holding CTRL is that if you do it in reverse it will cause a Horizontal Guide to be created.
    2. If done correctly your window should show a distance of the Radius (mine is 130)
    3. Measure Check
  21. Now open Excel or the Openoffice.org Spreadsheet and in separate columns record Width, Height, and if you like the Angle
    1. When recording the number please not that Halo Reach uses units that are 10x smaller than what we used so they must be recorded with a value of x/10
    2. In Excel
  22. Now click and hold on the “+” that is at the top of the circle and move it clockwise around the circle to where you want the next item to be.
    1. Hold CTRL to give you increments of 15 degrees
    2. When doing this make sure it touches the outside of the circle and the distance is as close to the Radius as possible (again mine is 130)
    3. Measure position 2
    4. Now Record those values again in the Spreadsheet
  23. Now repeat step 22 until you get to 0 on that fourth of the circle
    1. If you are doing unique angle all around the circle go around the whole circle.
    2. Please note that Gimp does not measure  a circle in 360 degrees, but in 90 degrees that are all positive.  when recording these number remember that some values will have to be negative when recording them in the spreadsheet.
    3. Positive and Negative
  24. This step is for those who have done a fourth of the circle
    1. This is my Values for every 15 degrees
    2. First Fourth
  25. now we will use Excel to convert the numbers for the rest of the circles
    1. we will start at cell A10 and go to C10 having that row equal A3 to C3.  Also For this group we will be doing the fourth of the circle where Height is Negative
      1. A10 set it to =A3
      2. B10 set it to =B3
      3. C10 set it to =C3*-1
      4. excel calculation part 1
    2. now select those 3 cells and grab the little black box at the right corner of what you just selected.  Drag it down to for how many total coordinates you got from the first fourth.
      1. should look like this
      2. excel calculation part 2
  26. now we will repeat step 25 for the third Fourth of the circle.  Just it will start at A17 and go to C17
    1. A17 is set to A3
    2. B17 is set to B3*-1
    3. C17 is set to C3*-1
  27. Now we will repeat step 25 for the fourth Fourth of the circle.  It will start at A24 and go to C24
    1. A24 is set to A3
    2. B24 is set to B3*-1
    3. C24 is set to B3
  28. step 26 and 27 look like this when done
    1. excel calculation part 3
  29. Now find the center of your map

Finding the center

  1. Load up your map in halo reach
  2. find the center of your map or where you want the circle
  3. create a flag stand (in the objectives tab)
  4. Place that object in the center of your map
  5. Hit “B” to open the coordinate Window and Hit “A” on the Coordinate placement
  6. Use the Length and Width to place this object exactly at the center of the map
  7. Record in cells D3 and E3 the Width and Height of the spreadsheet
    1. example: Center coliseum (63.5, 223.6)
    2. example: Center of Forge World (0.0, 0.0)
  8. Now input those numbers in to the Spreadsheet
  9. In Cell D4 and E4 set
    1. D4 set to =$D$3
    2. E4 set to =$D$3
    3. Then select those to cells
    4. Grab the black box on the bottom right of those to cells and drag down to till you do not need it any more (if you have to many it is fine)
  10. Now to add the cells together
    1. F3 set to =B3+D3
    2. G3 set to =C3+E3
    3. Then select those to cells
    4. Grab the black box on the bottom right of those to cells and drag down to till you do not need it any more (if you have to many it is fine)
  11. Steps 9 and 10 parts ‘A’ and ‘B’ should look like this
    1. excel calculation part 4
    2. Steps 9 and 10 parts ‘C’ and ‘D’ should look like this
    3. excel calculation part 5
      ** if you would notice that the first column of numbers (A-G) are organized how I described in the Guide above, while the second column of numbers (I –O) are ordered by coordinates that form a circle.  I have highlighted (in the second columns) where the points match up and you should only place one object at these coordinates.
  12. Now you are done with all of the calculations needed for placing items in a circle.  All you need to do is load up your map again and place the objects at the object coordinates column of the spreadsheet.
    1. *Note* Please Notice that we only calculated 2 coordinates for a 3 coordinate map.  These object must have a common coordinate; here it is the height.

What I have used this for

I personally used this to place respawn points around my AGLA Grifball map that I have made.

The GIMP File:


The Excel Spreadsheet Embed:

The Excel Spreadsheet for downloading:

Excel File for Circle