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Blog
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Written by HzR
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Wednesday, 29 October 2008 19:39 |
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One thing that could come in handy when you are constructing something in CAD is 3D-scanning. This is especially handy if you want to bring complex existing shapes into your CAD models. You might for instance want to scan a lexan body for your car, so you can check its fit on the chassis you designed. Or you carved a shape from clay, foam or wood and would like to modify it in CAD. You can also use it to overlay scans of machined parts with CAD data and check them against each other to see if you got what you designed. Trying to recreate surfaces in CAD will take a lot of work, and because it is very hard to measure curved 3D surfaces, the result probably won't be very accurate.
Up till now machines that could do 3D-scanning cost thousands of dollars and were therefore out of reach for the occasional hobby user. However, on a recent episode of the Revision3 show Systm they showed a software package that can scan 3D objects with the help of a simple web- or other digital camera and a laser line. You can be up and running with a very basic set-up for less then $100! The basic version of the DAVID scanning software used is free. If you want more functionality you can buy a more advanced version. A webcam can be had for as little as $30, and a simple laser will cost you about the same. The system also needs two back walls with calibration points behind the object so the sofware can figure out where the object is in space. This shouldn't cost much and be easy to build yourself from some wood panels and printed calibration sheets. If you are looking for the best results and have some more money to spend, you can get more accurate scans by upgrading to a higher resolution camera and a better quality laser. For such a setup you can easily spend around $500. The way the scanning works is as follows: - Set up the back ground walls with the calibration points.
- Put the camera in a stable fixed position.
- Calibrate the software.
- Put the item you want to scan in front of the walls.
- Switch on the software.
- Run the laser line over the object top to bottom.
- The software captures the laser beam bouncing of the object with the camera and converts it to a 3D points cloud.
- You're done!
You repeat this procedure on the object from several directions until you have captured all the surfaces of it. With the software package you can then put those scans together to recreate your virtual part. Check out the episode of Systm where they demonstrate how to scan an object and convert and transfer it to CAD-software. They explain all the steps involved and show you how to scan an object and stitch the scans together to get a closed volume 3D model. To download the scanning software, more extensive information about 3D scanning and setting up your system, a forum with lots of tips and tricks and more, go to the DAVID 3D Scanner website.
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