Projection in 3D perspective

Hello All,

I am having trouble with an installation I'm working on. What I am trying to generate is a set of catenary lines that are pulled back to a set of points midspan that forms a triangle in plan. From one particular perspective the lines line-up up perfectly. When the viewer moves, the lines shift - I'm trying to play with the parallax effect.

It would be easy done manually - analog using a projector, but I would like to develop this with a definition. So far I've developed the lines and tried to 'fudge' it but it doesn't turn out. I've tried Pulling et cetera, but the result is without the perspectival distortion, which is what I want to do.

Thanks!

Attachments:

Screen shot 2011-02-20 at 8.49.54 PM.png, 366 KB

Replies to This Discussion

Permalink Reply by Kevin McClellan on February 20, 2011 at 8:07pm

And the GHX screen shot ... might be a bit confusing, sorry ...

Attachments:

CaternaryInstallation.png, 1.5 MB

Permalink Reply by Victor Leung on February 20, 2011 at 9:33pm

Hi Kevin,

I wanted to help but could you upload the ghx and the rhino?

Permalink Reply by Kevin McClellan on February 20, 2011 at 10:17pm

Hi Victor,

Yes, of course, here's the GHX. Though please note that this file doesn't try and solve my problem, it's a different approach that I was testing. The Rhino file is empty - so I'm not uploading one - all the geometry is within the definition.

Thank you!

Attachments:

CatenaryInstallation.ghx, 829 KB

Permalink Reply by Victor Leung on February 20, 2011 at 10:59pm

Hi Kevin, your script is pretty complex, I fail to understand the thing you are trying to do in a few minutes, and I'm giving up. But referring to your topic about 3D projection.. I think the idea is that if you have defined your view point, you plot a series of straight lines from your view point to the object, then depend on the surface you want to project to, draw a plane (if flat) or draw a brep (3D) to find the intersection with the projecting lines.

I have tried to select one line in your script and projected it to the wall as an example.

Permalink Reply by Victor Leung on February 20, 2011 at 11:05pm

The definition for the above image

Attachments:

CatenaryInstallation_projection.ghx, 905 KB

Permalink Reply by Kevin McClellan on February 21, 2011 at 8:58am

Victor, just now jumped in to play around with the GHX. That's exactly what I was looking for - it solves my problem perfectly. Hadn't thought to extending the lines through a point nor to look for the Brep intersection. Thank you again!

Kevin

Permalink Reply by Kevin McClellan on February 21, 2011 at 7:23am

Hi Victor, Looks really promising. I'll take a look and see if I can make it work - Thank you!

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