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How to Reverse Engineer Physical Objects

Reverse Engineering on dark grey background

Reverse engineering physical objects is a process that basically involves reproducing a product – often either digitally or on paper – through a careful and detailed examination of its construction and assembly. This process of acquiring and analyzing detailed design information is useful for detecting design flaws, analyzing product specifications for commercial reviews, and even competitive analysis. Every man-made product – and even some organic ones – can be reverse-engineered given the right tools, with every reverse-engineering process being unique. But almost always, the start of the process will entail taking the object apart to understand its inner workings and mechanisms. This crucial first step is the first big obstacle to those just getting started with reverse engineering.

Video Tutorial: How to Reverse Engineer an Object

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Fortunately, programs like Scan2CAD can help make this straight-forward and much less confusing than it has to be. Although the steps taken can be quite involved and might take a little time to understand, it’s one of the best ways to digitize and recreate a product part that’s difficult to find or procure otherwise. Today, we’ll go through some of the more complicated steps in using Scan2CAD and help you convert your physical objects to vector files that you can easily use for reverse engineering. High-quality CAD and vector files are immensely helpful during reverse engineering, and Scan2CAD is the easiest way to produce them.

A reverse-engineered 3D scan of a machine part

A reverse-engineered 3D scan of a machine part Source

Step 1 – Scanning or photographing the object

A low-quality scan of a machine blueprint

A low-quality scan of a machine blueprint Source

It is imperative that before we digitize an object using Scan2CAD, we get a high-quality raster image that is suitable for automated conversion. Ideally, the preference is to use a high-quality scan of the object. The settings for a good scan are as follows:

  • Make sure to set the scan file format to TIFF or any other similarly lossless file format. JPEGs will typically have some details lost in the scanning process since it isn’t a lossless file type so try to avoid this file type if you can.
  • Set the DPI at the range of 300-500. Anything lower than 300 DPI will give you a low-quality and often pixelated scan and anything higher than 500 DPI will give you unnecessarily large file sizes with no additional benefits.
  • Monochrome or black and white scans are best for the purposes of Scan2CAD automated conversion. You can use grayscale scans and colored scans as well, but these will still inevitably be turned black and white on Scan2CAD before being converted into vector files.

When a scan of the object isn’t possible, photographs can also be used for Scan2CAD given the right setup. Here are the settings for taking a photograph for conversion on Scan2CAD:

If you’re converting an image of a physical object it’s important that you acquire a suitable image in the first instance. Here are some key tips:

  • Just as with scans, make sure to set your photographs to lossless file formats.
  • Set the object against a background with a contrasting color. Specifically, place a light-colored object in front of a uniformly black background and place a dark-colored object in front of a light background.
  • Ensure that the camera is parallel to the object and is pointed at it directly. This is to prevent any prospective distortion to assure that the resulting photo is an accurate depiction of the actual dimensions of the object. Ideally, you could take a picture of the object from far away using a telescopic lens.
  • Set the lighting so that the object has minimal shades and is not obscured or covered with shadows. Any shades and shadows picked up by the photo will be included in the output when Scan2CAD runs the conversion process.

After acquiring a high-quality raster image, take the extra time to double-check the image and to edit out any unwanted speckles, distortions, and image noise. Re-do the scan or photograph if you have to. Scan2CAD does have some editing tools you can use for any last-minute edit, but it’s best to use dedicated image editing software to really clean up your raster image before converting.

Step 2 – Converting your image to a vector file

Vectorized spanner on Scan2CAD

Vectorized spanner on Scan2CAD

The next step involves opening your raster file on Scan2CAD and proceeding with the actual conversion process there. This basically involves doing last-minute edits on your raster image, optimizing the vectorization settings for your image, optionally making last-minute edits on your output vector, and then saving the file. Here are the specific steps:

  1. After opening up the file, choose the Edit > Grabcut tool. In the dialogue box that opens, either click on ‘Use whole image’ if you want to convert the entire image or click and drag to create a rectangular selection detailing the area you want to convert. Then on ‘Confirm selection’.
  1. Scan2CAD will automatically take out the background but in cases where you want to do it manually or if Scan2CAD missed some areas, click on ‘Background’ and scribble a line or two on areas that are supposed to be backgrounds. Click on ‘Run’ to execute any changes and then ‘Next’ to finalize.
  1. The next screen brings you to the finalize object and here, you can choose to use the ‘Smooth’ slider to smoothen any jagged edges in the image. Click on ‘OK’ once you’re happy with the result.
  1. Additionally, if there are any other small cleanup actions you want to take, you can click on the Clean Image dialog box located at the top left of the screen. If the option is available, tick the ‘Threshold (Black & White)’ option under ‘Color Reduction’. This turns your image black & white and makes it suitable for conversion. If the option is grayed out, that means your image was already black and white and no longer needs to be monochromatized which is the case if you’ve already used the Grabcut feature.
  1. Although at this point, any major edits should have been done beforehand, there are also additional options under ‘Clean Image’ that you can use to do any small last-minute changes.
  • Remove Speckles & Holes: for any small clusters of pixels of white or black that need to be removed from the image
  • Thicken Lines: for any barely legible lines that need to be thickened
  • Smooth: for ‘jagged’ or pixelated lines that need to be smoothed out

Click on OK if you’re done with the ‘Clean Image’ dialogue after this.

  1. Other than the options under ‘Clean Image’, you’ll also have editing tools available on the left side of the screen. Most notably, you’ll be able to use the following:
  • Several ‘draw’ tools: separate tools for creating new raster lines in the drawing.
  • Draw text: to add raster text into the image
  • Erase: to take out any unwanted parts of the image
  1. If you’re happy with your edited and cleaned up image, click on the ‘Convert raster image’ tool . You’ll want to choose the ‘Outline’ option under ‘Vectorization Method’ and then click on ‘Run’ to generate a preview.
  1. You can then cycle through the tabs of both the original raster and the converted vector as well as a tab with both to see if the resulting vector is accurate enough for your tastes. The ‘Highlight vectors’ option can help you see the vector objects more easily. You can play around with the Vector definition slider if the preview is too jagged or too smooth; just be sure to click on ‘Run’ each time you make a change to generate a preview of your changes.
  1. Click on ‘OK’ once you’re happy with the preview to finalize the vector conversion.

Step 3 – Check and optimize the converted vector

Although it may be tempting to just run with the produced vector after using Scan2CAD’s raster-to-vector conversion, it’s always important to double-check the result and do any last-minute edits that need doing.

The draw, text, and erase options that were available to edit the original raster are also perfectly well-suited for editing any vector objects. At this point, make sure that the lines of the vector are perfectly straight, the angles are correct, and make sure that any bezier curves are converted into arcs or polylines for optimal compatibility with CNC machines. Scan2CAD also has a nifty ‘Convert vector image’ tool to do these optimizations for you.

Once your vectors are all optimized, all that’s left is to click on the ‘Export’ button at the top-right and set your file name and format.

Conclusion

Although do bear in mind that a discerning eye and careful double-checking is always integral when it comes to these kinds of processes, reverse-engineering doesn’t need to be any more intimidating than it has to be. Especially when you have Scan2CAD to do most of the heavy-lifting when it comes to reverse engineering and digitizing physical objects. 

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