Topic: Vectorize shadows

[Eycki]

Maybe this is not the right place to ask. 
I want to get the contour of a shadow as a 3D polyline or projection of the shadow as a 3D face.
Is there a possibility to get this done with AutoCAD and .NET?

[Eycki]

Nobody has an idea if it would be possible to vectorize the shadow from AutoCAD?

[Gasty]

Hi,

If the shadow is an image, you should get the image and  process that image independently of AutoCAD, and use some contour detection algorithm to get the boundary of the shadow, and then, map that boundary (may be a lot of them) into a polyline or any other suitable vector geometry in AutoCAD. These algorithms are usually very sophisticated as they are implemented to recognize features in medical and satellite images.

Try this link as a start: http://www.eecs.berkeley.edu/Research/Projects/CS/vision/grouping/resources.html
Also you can try IEEE Transactions on Medical Images for state of the art in this topic.

Gaston Nunez

[dgorsman]

Could also look into ray tracing.  But like the other method mentioned this isn't trivial in either execution or creation.

[Eycki]

I'm not looking for the rendered shadow.  There is a real-time shadow in AutoCAD which I want to vectorize by a button click. I thought maybe it would be possible to get the outlines through .NET API.

[Eycki]

I can't believe why there is no plugin for AutoCAD like 1001shadows for SketchUp. I could do my shadow analysis in Sketchup en export it again to use in AutoCAD but it would make things so much easier if someone knows how to make the same plugin for AutoCAD.

Video of 1001shadows: http://www.youtube.com/watch?v=NaLWS_zbP8k
Their website: http://www.1001shadows.com/en/index.html

[dgorsman]

The vast majority of AutoCAD users are still 2D, or limited 3D for clearance/sizes only with no need for shadows or lighting.  But isn't that one of the beauties of AutoCAD, that pretty much anybody can write one.   

I'm sure somebody here *could* but there's the whole thing of time, energy, money, existing work responsibilities...  it may take some money, or at least a few beers, to get somebody started.