resampling DST files

sampling_demo3

Our Quilt Plotter’s rather frustrating software automatically resamples DST files, for no explicable reason. While we struggle to communicate with its manufacturers to overcome this “feature,” I attempted to explain the problem in pictures.

1. A line, or vector file, is not a DST file yet. A DST file is comprised of many points, like so:

1. A line, or vector file, is not a DST file yet. A DST file is comprised of many points, like so:

2. This has a high sample rate, because there are many points spaced close together.

2. This has a high sample rate, because there are many points spaced close together.

3. Above is a lower sample rate, with "stitches" in black. There are fewer points and they are spaced further apart.  The machine always, always, automatically RESAMPLES DST files, which inevitably degrades line quality. Here's a resample at the same sample rate (frequency/spacing of points):

3. Above is a lower sample rate, with “stitches” in black. There are fewer points and they are spaced further apart. Here’s a resample at the same sample rate (frequency/spacing of points):

4. Every time the path is resampled, it moves further from the original line. This happens even if it's resampled at the same sample rate, as shown here.

4. Every time the path is resampled, it moves further from the original line. This happens even if it’s resampled at the same sample rate, as shown here.

5. Same sample rate, worse fidelity because of resampling.

5. Same sample rate, worse fidelity because of resampling.

6.  If we resample enough times eventually our path won't resemble the original line.

6. If we resample enough times, eventually our path won’t resemble the original line.

7. Not what we want.

7. Not what we want.

 

 

 

sampling_demo30008

THIS is what we want the machine to read. We can control all the points in the DST file in Mathematica. We just want the machine to not resample them, to keep the points in the original file we give it. Here the points are evenly spaced except at corners and curves to preserve fidelity.

3 comments to resampling DST files

  • Anonymous Coward

    That’s also what happens when you resample alcohol in a short period of time. Maybe that’s what they were doing when they designed that feature :D

  • People do things for reasons, at last usually, don’t they? So why did they program the machine to resample? Is it to homogenize the input into something friendly for the use of the software?

  • Cam

    I remember at uni when programming robots you had two types of path points ‘approximate’ and ‘exact’ (I cant remember the exact names but thats the idea).

    Approximate points were ‘in the general direction’ that the robot arm passed through (imagine it to be the black line in the above).

    Exact points forced the arm to move through the point exactly.

    Approx points caused so many ‘clang’ impacts of the robot arm on the safety rail as the robot arm cut corners.

    Did you ever get this solved?

    Have you tried asking the manufacturers if there is a ‘raw’ format for the machine that you can use? Maybe there is another language it talks that has more features or actually allows you to specify exact points. Then you’d just need a DST to ‘raw’ format converter. :)

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