New User - Entering Coordinates

Greetings. New user here.

I am working through the manual. I am on the first tutorial where I am drawing a pull toy.

Everything is working exactly as the manual states but I don’t understand something.

  1. On the Solid menu, click Cylinder.
  2. At the Base of cylinder… prompt, move the cursor to the Front viewport.
  3. Type 9,6.5, and press Enter .When you only type x- and y‑coordinates, the z‑coordinate is automatically 0.

The “9” moves in the X direction 9 places. OK
The “6.5” moves in Z direction.
The final “0” appears to originate along the Y axis.

I thought coordinates were given in X, Y, Z. That is even what the exerpt above shows.
And I just noticed that the vertical constraint is set to vertical yet the cylinder appears to be moving parallel to the Y axis.

I know this must seem really dumb but what am I missing?

There is a world coordinate system which never changes.

Each viewport has a construction plane called a Cplane and there is a coordinate system associated with that Cplan. Assuming you have the grid and coordinate axis lines enabled you can see the Cplane coordinate system. The grid is on the Cplane z=0 plane.
Standard Top and Perspective viewports: Cplane coordinate system coincides with the world coordinate system.
Front viewport: Cplane x coincides with world x, Cplane y coincides with world z, Cplane z coincides with world -y
Right viewport: Cplane x conicides with world y, Cplane y coincide with world z, Cplane z coincides with world x

Coordinates entered are interpreted as being in the Cplane coordinate system of the active viewport.

To enter coordinates in the world system preface the coordinates with a “w” such as w9,6.5 or w9,6.5,0

The User’s Manual and/or Level 1 manual discuss this.

2 Likes

Thank you for the quick reply.

I went back and found the reference in the manual. I guess what kept throwing me is the XYZ indicator (World coordinate?) in the lower left. I keep thinking in terms of CNC and Z means up and down… Not Y.

I am new to Rhino and I am coming from Solidworks / Fusion360. It reminds me of riding a three wheeler (ATC) for the first time in the 80s. I had ridden motorcycles all my life and all I could manage to do on the three-wheeler was run over the back of my legs. That is how I feel with Rhino right now.

In the world coordinate system used in Rhino z is up.

Have you changed Cplanes from the default?

Unless the Cplane is changed the world coordinate axis shown in the Top viewport show x and y. The Top view is from above looking straight down. The Perspective viewport uses the same CPlane as the Top viewport.

Unless the Cplane is changed the world coordinate axis shown in the Front viewport show x and z. The Front view is from the front looking horizontally, perpendicular to the direction in the Top viewport.

Added: Do you usually work in the Top, Perspective or Front viewport? I have not checked the tutorial you referred to but it may assume the user is working in the Top or Perspective viewport and you are working in the Front viewport.

This may be the root of your difficulties. Solidworks uses y as vertical.

In more than a few mechanical design systems, X is horizontal, Y is vertical, and Z goes into and out of the screen, as viewed normal to the “front” view. This includes SOLIDWORKS, where all users know that “Y is up.” In the Architecture, Engineering, and Construction (AEC) world, however, it is common for X to be horizontal, Y to be vertical, and Z going into and out of the screen as viewed normal to the “top” view. In other words, in the AEC world, “Z is up.”

Hello David,

Thank you. These posts of yours helped me to. While I am still “young” at Rhino, I did not know anything about the coordinate convention systems used in these other programs. Now I have a better understanding and perspective on this matter.

Thank you,

Andy

Thank you David. The problem is with me and not Rhino.

The tutorial is working in the front viewport. As per my observation and your elucidation in your first reply, the Y plane acts like a Z plane. That may not be the best way to describe it but that is the way it seems.

So the green line represents Y and yet the world coordinate “triangle” shows Z. This is what was confusing me. To be honest, I can’t understand the logic behind changing how coordinates are entered based off of which viewport is active. BUT… I am trying not to ask “why” until I have RTFM. *

I re-did the tutorial and if you enter everything the way it says it works. I then went back and entered a w before the coordinates and entered them in the way that seems logical to me and it also worked.

*As an aside, when working with the trial I was dumbfounded that I couldn’t change parameters. So I would call the sales guys to see if I could get some insight. Their answer was always, “Because it isn’t designed that way.” which is kind of like a parent telling a child, “Because I said so.” Finally I put two and two together and realized that you can’t enter parameters because it isn’t parametric. Not being able to edit parameters still makes my head spin.

*They assured me that parts can be edited and I see plenty of people using it so I know this must be possible… but I really need to RTFM because at this early stage I can’t see how I might change, let’s say spacing for a mount to have holes 25mm on center rather than 20mm on center easily. I need this program for practical reasons and so far I haven’t seen any light at the end of the tunnell. I keep having to go back to a parametric modeler when I need to build something. I know this is a good CAD system. I know the answers are there… I just haven’t found them yet.

Thanks again for the VERY helpful response!!

As you figured out Rhino is not parametric. Grasshopper is a companion to Rhino that allows designing with explicit parameters, but probably is completely different to what you are used to in other CAD software.

I don’t think there is any method in Rhino to change the spacing of holes as there is in some parametric software. The fastest way in Rhino to move the holes may be to delete them and create new holes in the desired position. That can be a very different way of working. The flip side is there are not parameters to keep track of when modeling.

Manuals to read and work through the exercises:
User’s Guide Rhino User's Guide
Level 1 Manual Rhinoceros Help
Level 2 Manual Rhinoceros Help
Rhino - Learn to use Rhino