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Customizable Luggage Tags

by slumou Mar 18, 2019
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I found the discussion online and this fix is not really intuitive. What does your image look like?

I have removed my comment. The fix had stopped the GCAL error but I still had an issue. The flag image on the back of the tag was raised up from the rest of the tag. It would not have printed with that "gap" between the flag and the tag. I have changed the Scad file (sort of a hack) and it is now working and printing. I will keep you posted.

Note: my fix is a hack and not pretty.

For those that are interested, here is what works for me. This code starts at line 46 of the original Scad file.
difference () {
union () {
difference () {
roundbox (90, 60, 3, 2, 5, 2);
translate ([52,30,-9])
surface(file = imagefile, center = true, invert=false);


I will have to test this with some other images. I used a black and white image and this should have mapped to 0/1. I suspect you are getting other values from a non-binarised image, and I did not thoroughly test with that.

I used Windows Paint to create my flag. When i viewed the image in OpenScad it shows the flag but it has a flat section at one end. That end was inside your Tag. That causes the "gap" in the middle of the tag. That is why I did not use the rotate([0,180,0]) in my code. That causes the flat section to be at the other end of the flag image. Not sure what is causing the flat part. Strange.

I grabbed a CA flag (presumably what you are trying) from Wikipedia, and made it mono and scaled to 90x60 in Gimp 2.10. This then rendered perfectly without having to change anything. Here are the files I used/made. Clearly my code isn't handling the unusual cases welI; I should fix this.

I created a new .PNG file using Photoshop. When I use your version of the code it leaves the flag image 'floating'. If the flag will not be attached to the tag. I have attached my .PNG file

I will do some more testing with you original Scad file. May be my Windows Paint version of the Canadian flag. No worries.

Thanks for the file. I think the problem was indeed that those were not black areas, but grey areas. I changed my code somewhat so there should be no more floating artefacts from differencing (because there is no longer any surface differencing). Try the V2 file.

Still does not work. First I get the same error when I F6 in OpenScad:
ERROR: CGAL error in CGALUtils::applyBinaryOperator union: CGAL ERROR: assertion violation! Expr: itl != it->second.end() File: /opt/mxe/usr/x86_64-w64-mingw32.static/include/CGAL/Nef_3/SNC_external_structure.h Line: 1102

If i change your Line 59 to have a .01 added or subtracted, it compiles in OpenScad:
translate ([52,30,0.5+.01]) or translate ([52,30,0.5-.01])

But, the .STL has a one or two layer gap between the flag and the tag.

It must be my flag image. Being 8bit greyscale I assume that is the problem. I will try to convert to Black and White when I get a chance.

I wonder if it could be version-related. I am using 2015.03 on Mac and I did not get errors when using your image.

I am using 2015.03-2 on Win 10pro. No rush on this as I have hacked the code to work.