We purchased the city image from a stock photography website. The software used to generate the city image was a combination of Rhinoceros 5.0 (NURBS modeler) and a plug-in called Grasshopper (a parametric modeler). A grid of points (representing the circle center points) was overlaid on the image. A custom script was written which analyzes the greyscale value of the pixel located at each grid point and we used the greyscale value to control a circle radius that the CNC followed.
While this was created with a custom script, this could also be done with free software called Rasterbator to pixelate an image and then using 'live trace' in Adobe Illustrator to get vectors opposed to raster (there are free versions of Illustrator-equivalent software online). Scroll below to the Rasterbator link with instruction and then we also linked an article from Instructables about how to use 'live trace' in Illustrator. Once you have vector outlines in illustrator that file can be cut on any CNC software.
The 24” x 36” aluminum sheet is secured to the ShopSabre 4896 CNC machine using 3M double-sided tape. Hundreds of holes and cuts using Amana Tool’s CNC router bit reveals the Aluminum City design.
We used a black frame LED light box which contains hundreds of LED lights to frame and backlight the Aluminum City art piece for illuminating results.
Feed, Speed & Step Down Technical Information:
1/8” Dia Solid Carbide Spiral ‘O’ Single Flute Aluminum Cutting CNC Router Bit #51474
Feed Rate (IPM): 40”
Speed (RPM): 18,000
Surface Feet Per Minute (SFM) 600-1,000
Chip Load (Per Tooth): .002” - .004”
Step Down (Per Pass): 0.0625”
Aluminum City CNC LED Lightbox Project Video Using Amana Tool® Solid Carbide Spiral 'O' Flute Router Bits Video, by ToolsToday, Your Source for Industrial Cutting Tools
Instructables article on making vector paths