Simple Path Shapes (link HERE.)
(Please also download the scripts that are included with this plugin)
Mura Meister Copies (link HERE.)
Please remember that .scm files are scripts and go in the scripts folder, and .py files are plugins and go in the plug-ins folder of your user folder .gimp-2.8. If you are using a Mac or Linux machine, you'll need to make sure your .py files are executable.
This method came about from a post on GIMP Chat that can be found here.
I will only be focusing on one small area of the skyline, so I will crop that area I want to use for the digital mandala.
Step 2: To keep the image consistent in the rotation, we will use a pie shape to accomplish the mandala. First, we need to open a new transparent image with a large enough canvas to host the new mandala pie. The size of canvas you need depends on the size of the cropped image. The one you see above was 1000 x 1044px, so my new square image will be 2100 x 2100px.
How did I come up with that size?
Well, the absolute height of the image is 1044, so I doubled that and rounded up. Width doesn't matter since we are going for a complete square image.
Notice that I centered a copy of the cropped area onto the new transparent canvas with centered guidelines to help me guide the pie slices in the rotation.
Step 3: Now it's time to add the 1/8th pie slice using Simple Path Shapes. Selecting 1/8 pie, you'll end up with several path shapes but you only need ONE of the 1/8 paths, so you can turn all the other paths off by clicking the eye next to each.
The path and image are both perfectly centered. Yes, I mean perfect, using simple math. Half a rotation of 45° is 22.5°. That is how much I rotated the 1/8th pie path. Just keep in mind that the Rotate tool allows you to adjust the center, like shown here:
See that little circle on the crosshairs of the guidelines? That is the rotate center point and it can be moved to wherever you want it. I chose the EXACT center of the guidelines, for obvious reasons.
Step 4: Now it's time to copy and flip the path selection of the area of image we want to create a mandala from. So, activate the selection while the pasted image layer is selected, selecting the canvas layer will result in an empty copy.
Halve your selection using the Free Select Tool with mode set to "Subtract from the current selection - CTRL". It doesn't matter which half you select since you can always flip the selection horizontally afterwards.
Copy that selected area, and then paste it as a new layer. Center it back to the canvas, and turn off the pasted layer.
You'll notice I duplicated the first 1/16th pie copy and then flipped it. Then merge the two copies together as one layer. Run Mura Meister Copies, selecting the exact center coordinates of your canvas, (mine was 1050 x 1050) and run 8 copies of the merged layer.