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Load backdrop

PostPosted: Mon Aug 30, 2010 5:38 pm
by ThunderCat
Is this feature disabled in the demo version?... I want to load a background image (which contains my knot) so I can trace it in KnotSolver.

On a related point, can I upload a text file with an image? That is, rather than drawing the knot, can I input its position?

Thanks in advance

Re: Load backdrop

PostPosted: Mon Aug 30, 2010 7:23 pm
by rob
ThunderCat wrote:Is this feature disabled in the demo version?... I want to load a background image (which contains my knot) so I can trace it in KnotSolver.

On a related point, can I upload a text file with an image? That is, rather than drawing the knot, can I input its position?

Thanks in advance


i assume you mean KnotPlot.

the feature is not disabled in the demo version, but appears to be broken in all versions. i will try to fix that for the next release.

in the meantime, there is a workaround. do the following:
  • create a PPM version of your knot image. Photoshop or ImageMagick can save files as PPM. this example will assume that you called it knot.ppm but you can use any file name
  • put this file in a directory/folder where KnotPlot can load it. on Windows, you can put it in the KnotPlot installation folder. on a Mac, i recommend you put the KnotPlot application in its own folder /Applications/KnotPlot and this is also where you can place the image file.
  • go into the Sketch control panel in KnotPlot
  • into the KnotPlot Command Window, type something like
    3dop bgimage knot.ppm 54
    show bgimage

    if the image is too small (or too large), retype the first line replacing 54 with a smaller (or larger) number (i.e., the image size is inversely proportional to the value you use) you can hit the up arrow key to get to a previously typed command. then just backspace and type a new number and then hit return. you don't need to retype the second command.
  • sketch your knot

Re: Load backdrop

PostPosted: Tue Aug 31, 2010 4:13 pm
by ThunderCat
Thanks, Rob!

I'm slowly coming to grips with KnotPlot (sorry I called in KnotSolver).