Curve : ProjectCurveOntoPlane error


I inserted a 3D linestring from an alignment as a reference and generated a PolyLine from it using the PolyLine node, the problem is when i try to use ProjectCurveOntoPlane and use BaseCS.XYPlane as my Plane, i get an error saying check alignment of the curve, What I'm trying to achieve is to get a 2D projection of my 3D PolyLine.

I'm using GC from OBM.



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  • Hi Crisanto,

    I had a quick look at the file, just wondering did you use a AECtrasnform to get this referenced back around the file origin? That might be the issue.

    I moved the reference close to the origin and it appears to project onto the xy plane.

    Attached sample.

    Hope that helps



  • Hello Crisanto,

    I think Wayne is right. Working far away from origin makes it harder for the computer to do the calculations. So it is always better to work near the origin. 

    However, as a workaround, you may follow this. 

  • Hi Wayne,

    Thanks for your input, that is what I'm thinking because from the SIG videos i watched the elements that are projected are very close to the origin, in my case my alignment is on real world coordinates. I'm quite new to GC and I didn't used a AECtransform.

    Do i need to move the origin/acs next to my reference? cause moving my reference next to the origin would change the coordinates and if i attach this model as a reference it would be out of place.

    I'm having an error whenever i try to open your file.



  • Hi Wayne,Anik

    I got it! i created another coordinate system ByUniversalTransform and moved my reference to the origin. I was able to project the curve onto the XY plane.



  • Hi Cris,

    As others mentioned it can be problematic working too far from origin: The work-around that I use is to have 2 coordinate systems, 1 "baseCS", 1 offset CS. When you reference a file into your design use the offset origin (calculate this so that it brings it central to the model origin). When you are finished processing, you can do the opposite and transform the contents of your design from the offset to the base cs and this will reproject the geometry to real world coordinates ready for exporting. As a side note, one thing to bear in mind is that you should turn off the visibility of the offset CS since having any visible model objects really far apart from each other in Microstation will cause rendering issues, it doesn't affect your design but it will become difficult to zoom in without glitches cause elements to disappear or look inaccurate.

    Hope this makes sense, it seems a little cumbersome at first but it will really make a big difference to the accuracy of your design due to floating point rounding errors; the larger the whole number is the less decimal places are available since the decimal "float" is pushed further to the right (we only have allocation size we can work with).