Author Topic: Engrave and Trace (sketch plus) issue  (Read 899 times)

laser_cutter

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Engrave and Trace (sketch plus) issue
« on: November 05, 2017, 12:20:45 PM »
There seems to be a small issue (1mm about) issue with sketch plus overlay.

ISSUE:

Trace seem to be off center by 1mm about.



attached is the png file used to create.

T2 is set to Center start point.


Any ideas on how to fix the slight misalignment?

Zax

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Re: Engrave and Trace (sketch plus) issue
« Reply #1 on: November 05, 2017, 12:34:09 PM »
Yes, good eye! There is a very small trace offset but typically less than 0.25 mm.

If you manually trace it is possible to shift it in any direction depending where you click, it's to do with the way a trace is generated (following the contrast) and the resolution.

I don't know what you are using it for, in most cases it's to contour cut out the engraving and the power is usually higher so there is no visible difference. If you are using it to enhance the edge then I also doubt you would see it in the engraving, but it's possible.

laser_cutter

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Re: Engrave and Trace (sketch plus) issue
« Reply #2 on: November 14, 2017, 02:49:59 PM »
Yes, good eye! There is a very small trace offset but typically less than 0.25 mm.

If you manually trace it is possible to shift it in any direction depending where you click, it's to do with the way a trace is generated (following the contrast) and the resolution.

I don't know what you are using it for, in most cases it's to contour cut out the engraving and the power is usually higher so there is no visible difference. If you are using it to enhance the edge then I also doubt you would see it in the engraving, but it's possible.

I am using the trace to cut out the image. The offset is noticeable.
How do I shift the offset?

Is the offset intended? Can the offset be removed from the program entirely?
« Last Edit: November 14, 2017, 02:57:58 PM by laser_cutter »

laser_cutter

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Re: Engrave and Trace (sketch plus) issue
« Reply #3 on: November 14, 2017, 03:14:39 PM »

The red dots represent where I clicked to trace each entity. The offset is in a different location for each entity even though respective to each trace the same point was selected.





Viewing the image below (not the same engrave and trace as the screen grab above) the offset cut off features of the image


Zax

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Re: Engrave and Trace (sketch plus) issue
« Reply #4 on: November 14, 2017, 06:21:27 PM »
The trace works by moving RIGHT until it locates the edge (detected by contrast change), then it follows the edge until it reaches the start point. Now, if it doesn't find an edge after a certain distance it will start moving left from the clicked point but that is unusual.

In your example the first point it finds is always closest to the contrast, then it traces the edge and can be a small offset.

I have an idea how to improve this, but can't guarantee anything until I test it as there may be other undesirable effects.