How to create a solid that represents the shadow of an object projected by a point light source? 1

[please_dont_crash]

I'm not really sure how to approach this.

My goal is to end up with a solid volume that matches an object's shadow, given an object and a location in space that represents a point light source.

Imagine a complex object, like a pineapple. Define a point above and to the side of the pineapple. This point represents a light source. How would I be able to create a solid object that matches the space encompassed by the pineapple's 3D shadow? In other words, not just the projected curve of the shadow's outline on the ground, but the actual volume of space that is not lit? Conversely, I could instead ask how to get the 3D object that represents all areas lit by the light, excluding those in shadow.

I have a feeling this is tricky and would require several intermediate steps, but I have no idea how to approach this.


Thank you!

 

[jerry1423]

I just noticed something called Shadow Curve. It is in your Derived Curve menu.
I have never used this it but may be what just you are looking for.
It has an "associative" toggle so you can make sure it changes when the model changes.
With the curves you should be able to create a solid.

When I have time I may play with it.

Jerry J.
UGV5-NX1884

 

[please_dont_crash]

Wow thank you!

I found this really clear video which goes over the options:

https://www.youtube.com/watch?v=pu6SMlFOfhY

It looks like this is one half of what I need. So I would then ask:

Given a point and a curve on a plane, how would I trace out the surface that connects the point to every point on the curve?

Thank you!

 

[jerry1423]

It would probably help if you can show a picture of that point, curve, and plane.

Jerry J.
UGV5-NX1884

 

[please_dont_crash]

Sure thing.

https://i.imgur.com/9WCpFxu.jpg

 

[please_dont_crash]

Unfortunately I don't have a version of NX that has the Shadow Curve feature. I have NX 11.


Any other ideas on how to achieve this?

 

[jerry1423]

Maybe this previous post will help you

https://www.eng-tips.com/viewthread.cfm?qid=115478

Jerry J.
UGV5-NX1884

 

[please_dont_crash]

Thanks Jerry. I have been trying to get that to work for a while now, but when I press OK it hangs and never completes the task. I think the problem is I have a mishmash of extracted surfaces from a native NX body, along with some surfaces that came from a STEP file. I'll keep trying...

 

[jerry1423]

This post may help you with the mismatch

https://www.eng-tips.com/viewthread.cfm?qid=353723

Jerry J.
UGV5-NX1884

 

[mmauldin]

"Given a point and a curve on a plane, how would I trace out the surface that connects the point to every point on the curve?"

"Ruled Surface" will do that:

 

[please_dont_crash]

Thank you Jerry and mmauldin! Ruled surface definitely looks like part of what I need.