Intelligent filtering of Mesh Compensation datapoints?



  • I'm using the IR sensor (great!) with a PEI bed (uh-oh…). I followed the instructions for painting and curing the back of the PEI, and while it took a few tries, I finally got it glued to my aluminium bed, and it looks black enough for Nigel Tufnel and it is flat enough to print on most of it with no bed compensation.

    But when I try to do do a mesh bed compensation and , I get some bad datapoints. I don't know if this is caused by flaws in the paint or scratches on the surface, but I get some bad datapoints:

    I imagine my immediate solution is going to be sanding the top of the PEI and losing that nice, smooth finish. But I was thinking that a median filter (https://en.wikipedia.org/wiki/Median_filter) should be able to do a really good job of throwing out the outliers and making even that data usable. It might even be beneficial on bed maps not as pathological as mine.

    My other (related) suggestion is an option for a single G30 probe command to probe multiple points and average them.. Ideally you'd add NUMBER_OF_POINTS and RADIUS to the probe command, and the command would then probe that number of points around the given X,Y. I think that would be helpful (increasing accuracy and repeatability) no matter what kind of probe you're using.

    Should I add either to the firmware wishlist?


  • administrators

    Those both look Iike good ideas to me, worth adding to the wish list.

    Meanwhile, you could import the heightmap.csv file into a spreadsheet, apply a median filter to it, and re-export it. Then load it using G29 S1.



  • @dc42:

    you could import the heightmap.csv file into a spreadsheet, apply a median filter to it, and re-export it. Then load it using G29 S1.

    This is why you're my hero. 🙂


  • administrators

    Bear in mind that in the height map file, plain 0 with no decimal point means that the point was not probed. So don't change those values, and don't use them in the median filter calculations.



  • My other (related) suggestion is an option for a single G30 probe command to probe multiple points and average them..

    The new is a well-forgotten old.

    +1 for this feature. The same problems with IR sensor forced me to stop using it.


 

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