Newbie: Points Workbench

[freecad-heini-1]

Unfortunately I really need a lot of points. If I want to draw a marine screw propeller number of points needed can easily exceed 500 and much more.

Please have a look here:
https://forum.freecadweb.org/viewtopic. ... 26#p250126
https://forum.freecadweb.org/viewtopic. ... 25#p200725
https://peertube.mastodon.host/videos/w ... 7e7c6e3a13

[JoshM]

Thanks guys. I'm still wrapping my head around this, but the links should help.

One thing I'm curious about. In some cases, people are interested in forming a surface from points, but the points may not be ordered. In my case, I am interested in a radial and/or axial offset surface.

If I start with a hemisphere as an input surface, and if I offset radially, the result face should be two faces, a planar circular face at the top, and a portion of a hemisphere of larger radius at the bottom. Does a BSPline surface approximation make a singular surface approximation of the two, or do I get just the portion of a hemisphere?

I'm also a bit confused because the locations of the BSpline poles appear not to be on the surface itself. I'm hoping to go through microelly2's script on the 2nd link and better understand.

[microelly2]

Thanks guys. I'm still wrapping my head around this, but the links should help.

One thing I'm curious about. In some cases, people are interested in forming a surface from points, but the points may not be ordered. In my case, I am interested in a radial and/or axial offset surface.

in these cases you need another mapping.
I did some work last weekend to bump image data (colors as heights to arbitrary bsplines

and
https://youtu.be/MC_XRpfdcro
you can check the ideas here (code will change next day cleaning up)
https://github.com/microelly2/freecad-n ... #L350-L590

If I start with a hemisphere as an input surface, and if I offset radially, the result face should be two faces, a planar circular face at the top, and a portion of a hemisphere of larger radius at the bottom. Does a BSPline surface approximation make a singular surface approximation of the two, or do I get just the portion of a hemisphere?

you simply add the heights to the hemisphere and get the mountains and the sinks.
My method si stiull not optimized for s sphere but will come soon.
https://freecadbuch.de/doku.php?id=blog ... to_a_nurbs

I'm also a bit confused because the locations of the BSpline poles appear not to be on the surface itself. I'm hoping to go through microelly2's script on the 2nd link and better understand.

This is true and I said this example is a first step.
if you want to get the curves trought the poles there are different ways.
the best mesthod (for me) is to use bezier surfaces. These are BSplines with Multiplicities [4,3,3,3..4] for degree 4.
Than you have the well known behaviour from Inkscape Bezier curves
for the idea see
https://forum.freecadweb.org/viewtopic. ... 30#p249220
and here
https://youtu.be/02EZ_oteG68

[JoshM]

Thanks microelly2,
I'll look through links tonight. I really appreciate your insight.
Best,
-Josh

[Palmtree]

I am training to import cloud points (using the Points WB) similar this thread
I started with a test file of 4 points (a simple flat site of land to be used in setting up a house BIM model).
Meter is the unit of the modelled points' ASC file (Test.ASC)
My Freecad unit in preferences/BIM is in meters.
After importing points, connect them with a line, using the Part WB - Create shape - Face from Edges
Check the measurements of the created face (BIM WB ===> Utils ===> Survey)
Resulted measurement are in mm which is not meter unit as Freecad preference setting.
It seems that the imported points coordinates were considered as mm
Refer to attached files
This is not correct. Any comments please?

OS: Windows 10 Version 2009
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.24291 (Git)
Build type: Release
Branch: releases/FreeCAD-0-19
Hash: 7b5e18a0759de778b74d3a5c17eba9cb815035ac
Python version: 3.8.6+
Qt version: 5.15.2
Coin version: 4.0.1
OCC version: 7.5.0
Locale: English/Australia (en_AU)

[thomas-neemann]

if i understood correctly, a point cloud file has no unity. the importing system determines them.

[Roy_043]

After importing you can put the point cloud in a Std_Link and change the scale of that object. But you then end up with coordinates that are very far from the origin: over 6000km away. FreeCAD is not the right tool to deal with 6000,000,000mm+ coordinates. In fact most CAD programs would struggle in such cases.

[Bance]

Try the trails workbench....

but as Roy says there are problems with large numbers.

[937]

Hi,

I have no idea how to use this workbench. Are there tutorials? Besides the short wiki entry I haven't found any:

Draft commands such as Draft Line.svg Draft Line and Draft BSpline.svg Draft BSpline can be used to connect the points in a point cloud. Use Draft Snap Endpoint.svg Draft Snap Endpoint to snap to the points.

I did that, but the (red) lines I created don't connect the points, they are on a plane (not any of the standard ones) behind the points.

points-FreeCAD 0.20.png (13.47 KiB) Viewed 1082 times

Can I click or link to or move a single point? I was able to import this Stanford Bunny and then convert that to points, but I don't see how to interact with the individual points now. I can only select the entire object.

[Palmtree]

I will go back to focused on implementing this exercise using FreeCAD-Trails.
Your advice very much appreciated.