Find apparent/visible mesh faces and vertices

Replies to This Discussion

Permalink Reply by Kyle Faulkner on April 21, 2015 at 11:15am

You could try the Horster plugin. Get the camera position with that, draw a line from your points to the camera, test intersection, and cull whatever you want based with the results.

Permalink Reply by Sam on April 21, 2015 at 2:29pm

Thank you, but I'm afraid it isn't working too :/ ... I used the mesh/ray intersection component instead of the Breb/curve component. The result after 5 min of computation wasn't like expected. Just 30 vertices were left, out of 200 000. it's quite a complex mesh as you can see in the image.

AND the obstacle is the same mesh as the mesh for which I want to find the visible/invisible parts. I think that's maybe a problem. :/

Attachments:

• figure.png, 1.2 MB

Permalink Reply by Kyle Faulkner on April 21, 2015 at 3:22pm

I think if you offset the points from the mesh just a tiny bit should work. Otherwise the points will always intersect at the very start of each ray. I got it to work with a simple sphere. The Rhino capture shows two perspective views: the first is drive the rays and the second shows the resulting cull.

Permalink Reply by Sam on April 22, 2015 at 5:41am

Thank you! It's at least working for the sphere  ;)... now I've got another problem, because my mesh seems to have two consecutive edges with the same value and the wb_offset isn't working for my geometry. it tells me to use the wb_mesh clean component, but I've figured out that it is actually not existing. So I need another way to repair the mesh and to get a valid topology!

Permalink Reply by Riccardo Majewski on April 22, 2015 at 5:44am

I did more or less the same about the small offset.

(I've just moved center points away with normal direction)

I created this solution that find visible faces by starting with many meshes objects.

Should work with any meshes.

Heavy definition, somehow.

Attachments:

• mesh_shadows.gh, 45 KB

Permalink Reply by Sam on April 22, 2015 at 6:57am

Thank you! very nice definition too... My only remaining problem is to get a clean mesh to work with! it's the same problem with your definition. My mesh isn't valid and therefore not processed! :/

Permalink Reply by Riccardo Majewski on April 22, 2015 at 7:00am

What do you mean with not valid?

Can you attach it here?

Or, try weld everything in rhino with 180° and use "clean & combine mesh" component in GH.

Permalink Reply by Sam on April 22, 2015 at 7:08am

As I used the wb_offset component before the component returned an error. two consecutive edges with the same value were found, therefore wb could not use it.

now I had a problem after using the clean & combine mesh component you had in your definition. The output was an invalid mesh.

The file is to big to send it here. But db will do it:

https://www.dropbox.com/s/x6jex5h7y0k78kv/frauenraub_2_high%20detai...

Permalink Reply by Riccardo Majewski on April 22, 2015 at 7:47am

Fixed the mesh.... it takes time but works.

https://drive.google.com/file/d/0B85EoZOWwXBGZ1EtTEtfcVdHQnM/view?u...

Also i found a bug in my definition, to make it works, original mesh component must contain at least 2 meshes.

(If you need to work with a single mesh, just use Kyle solution then)

Or merge together a simple mesh, as you can see in this pic:

(results after "shadow" computed)

Permalink Reply by Sam on April 23, 2015 at 6:25am

Thank you very much!  :) It's working now with your definition!

Still I struggle with the wb_offset component in Kyle's solution! I'm aware that the Mesh I'm using is far from perfect! :D I need to find a better way to work with 3D scanned Objects!

Permalink Reply by Sam on May 21, 2015 at 10:11am

Hey! sorry for bothering you again! But maybe you or somebody else has an idea about my current problem... I have been using your idea of the definition  to work further on my project, but it turns out that even with a higher resolution model there is a problem occurring. The problem is some kind of stepping as you see in the picture below.

original mesh from zremesher and model with stepping:

I believe the problem occurs as the mesh is recomposed again in the Construct Mesh Component, because there is not the right amount of vertices and faces provided. it is a Dispatch component for the faces there, but not for the vertices. But maybe I'm wrong!? I'm not sure... 

here the workspace:

As I'm not very practiced in data structures (and I think I need to dispatch the vertices somehow), I hope somebody could give me a hint or could tell me what is wrong about my assumptions.

Thanks in advance!!

Permalink Reply by Sam on May 21, 2015 at 10:14am

here the files:

https://www.dropbox.com/s/j0aw2vwz9vcd8em/150521_mesh_in.visible.3d...

Attachments:

• mesh_in.visibile.gh, 15 KB