Replacing points in pointcloud with Tsplines quadballs

Hi,

(I hope that this is the right discussion tab, I am new here :) )

I have a point cloud, I want all the points in the cloud to be replaced by a tspline quadball, it's really that straight forward :).

I tried using points (multiple) with a geo (referencing to quadball) and using replace. however that logic is clearly lacking.

what am i missing to make this work?

thanks!

Replies to This Discussion

Permalink Reply by Damon on August 4, 2014 at 11:30am

Here are two ways:

Permalink Reply by Alexander on August 5, 2014 at 2:26am

Hi Damon,

Thank you however, is there a way to keep the quadballs in tsplines after I bake them? Because I need to use the tsplines bridging etc. after I have replaced them all.

Now if I bake them they become a mesh with no tsplines capabilities.

ciao.

Permalink Reply by djordje on August 5, 2014 at 3:20am

Hi Alexander.
Point cloud is a special Rhino object type, which Grasshopper currently does not support.
So when you say: "I have a point cloud" does that mean you have a bunch of regular Grasshopper points?

And what do you mean by: "I want all the points in the cloud to be replaced by a tspline quadball"? By "replacing" do you mean generating tsQuadball from those grasshopper points you have (they are not baked?)?
Or do you already have a tsQuadball, and you want to move it to an average point of your grasshopper points?

An explanation on these, screenshots and attaching your .3dm and .gh files would help us, help you.

Permalink Reply by Alexander on August 5, 2014 at 4:04am

Hi djordje,

I use eve_voronax on a existing polysurface (not just one surface), this program generates curves and points in different layers in rhino.Youtube

I select the point cloud layer and put that under grasshopper 'points', regular plain old points, the same as you can add from the menu bar.

then I make a quadball in the same file and couple that under grasshopper 'geometry'.

Then I use the .gh above, the first one. this works perfectly however after baking it loses it tspline functionality.

My goal is to use the newly placed quadballs and start bridging them similar to this,

youtube

it is impossible to use 'the tsplines 'pipe' function (i prefer to work in tsplines for its extreme flexibility) because of the complexity of the curves, i tried that first.

Tell me if there is still info missing, I will add.

Thank you for helping thus far!!

ciao.

Permalink Reply by djordje on August 5, 2014 at 4:24am

So in Rhino, you have a couple of points. You want to use them as centroids to create quadballs at each of those points? But as there are too many points, you do not want to create each quadball in Rhino manually, so you thought of using Grasshopper instead to automate this process.
That's what you meant by: "I want all the points in the cloud to be replaced by a tspline quadball"? Meaning: you want all those Rhino points you have to be used as a centroids for your quadballs?

If that is so, then all of the quadballs would have the same radius?

Attached .gh and .3dm files would still clear some of the misunderstanding.

Permalink Reply by Alexander on August 5, 2014 at 5:04am

Hi,

yes, The quadballs are the same radius. And yes to your internal logic, there are above 200 points so i need some automisation (the bridging will be manual based on the curve intersection, see layer Voronax diagram.)

Attached is the rhino and .gr file.

i have disabled the grasshopper 'geo' for easier transport.

ciao

Attachments:

combined joint voronax with grasshopper.3dm, 894 KB
replace point cloud for voronax.gh, 27 KB

Permalink Reply by djordje on August 5, 2014 at 6:51am

There is no way you could do this from grasshopper by referencing the Rhino quadball. It's because (as you already experienced) baking tsplines geometry converts it to some other brep format, which is not exactly what tsplines uses (they use brep format too, but one of their own). Tsplines guys haven't released their sdk, so not much more could be done about this.
The best solution would be to simply copy a single quadball to all of your points - Damon's script below, does exactly that.

Permalink Reply by Damon on August 5, 2014 at 6:41am

I really have no idea about keeping the geometry as TSplines geometry. Two ideas:

1. Here's a really simple RhinoScript I wrote 5 years ago that copies objects to points.

2. If the above doesn't work, perhaps it can be modified to CREATE TSplines quadballs at each point. What is the quadballs command? Take a screen grab of the command line as you enter the command so I can see the options... or somebody who knows TSPlines can modify the script.

Attachments:

CopyToPoints.rvb, 1 KB

Permalink Reply by Alexander on August 5, 2014 at 6:49am

Thank you, this is really a helpfull forum, i appricate that a lot!

I will try it out and see what i can do.

ciao,

Permalink Reply by Damon on August 5, 2014 at 7:14am

Here's a version that is for my option 2, it creates quadballs at each point. It could be further modified to give the user the ability to set all the various options for the quadball command, but right now it just creates a default quadball of user-chosen radius.

Attachments:

CopyQuadBallToPoints.rvb, 1 KB

Permalink Reply by Alexander on August 5, 2014 at 1:23pm

Hi Damon,

Thank you for the adjustment, however it appears that the code recreates the quadballs not on the exact point but above it, some predetermined x and z coordinates higher, making it look like the quadballs are floating in the space above the pointcloud, the mutual relationship among the quadballs seem spot on, though.

I have downloaded a .pdf tutorial on rhino script (printing it now) and started searching the internet for video tutorials. It seems that rhinoscript is more relevant than grasshopper for my journey...at least for now.

I will use your code to help debug and understand the coding language better.

thanks again.

ps. If you know any good video tutorials out there please let me know.

ciao.

Permalink Reply by djordje on August 5, 2014 at 1:47pm

You have altered the origin of your construction plane in Perspective viewport. Either set it to 0,0,0 ("CPlane" command) or simply select your points in some other viewport (like "Top").

Still I would again recommend using Damon's first script, as it is much faster to copy a quadball, then generate each one.

For rhinoscript, a nice collection of learning resources could be found in here.