Hi i am still kind of new to rhino and i have to create a topography surface. i have the contour lines raised but i still am unable to create the topo. would anybody be able to help? please i need to figure this out

Can you please post your 3dm file with contour lines?

suretopo updated.3dm (5.0 MB)

Your curves are all in the same plane. They are 2D curves.
There is nothing 3D here to make anything that has elevation relief.

but when you look at the front view the lines are all raised

so how do i make it 3d?


First, in Preferences>Modeling Aids>Nudge, set the nudge increment to the desired topo line elevation spacing. (how much you want a topo line to represent, 1 foot, 1 meter, etc.)

  1. You have to decide which curve or curves represent(s) the lowest part of the terrain (topo lines are arbitrary if they don’t have an elevation attached to them)
  2. Select the lowest curve(s) with Shift+click and hit the Lock button to lock them
  3. Cmd+A to select all the remaining (unlocked) curves
  4. Hit the “PageUp” key (if you have a wired keyboard) or fn+Up arrow if you are on a laptop or have a keyboard without PageUP. All the selected curves will move UP one increment.
  5. Select the next lowest curve(s), hit LockNote that several disconnected curves may be at the same height, so you will need to check your model all the time and make sure you have gotten all the curves at each level.
  6. Continue the above procedure of nudging and locking the lowest until all the curves have been mounted to the correct height, then use the Unlock button to unlock all the curves.
  7. Select all the 3D curves and try running Patch through them. The more control points you have the better it will conform to the topo lines; the stiffness setting also will influence the fitting of the surface.

HTH, --Mitch

thank you so much which one for the nudge would i change?52 AM

I would just change the Nudge key alone - easier that way. --Mitch

they in fact are slightly raised i could not find any indication for a tilted view. the curves are precisely 2 inches apart from each other and have the highest elevation at 96 inch which seems natural to me. so a simple patch might do to create a surface with these curves. the outline would have to be drawn projected to trim the rest off.

Yes, you are right, I didn’t look all that closely, given the fact that the XY extents is 365,042 x 192,835 units but only 110 units high. So maybe there was an incorrect Z-scale applied - maybe inches/feet confusion. In that case, you could just scale the curves 1D in Z, perhaps by twelve. Normally topo lines are in feet (US) or meters (most everywhere else). A height difference of 220 feet would make sense with a terrain that’s about 6 miles by 3, otherwise the variation is only 18 feet, i.e. for all intents and purposes, flat…


yes its kinda flat, but still steeper than the black rock desert :smiley: … at least i guess so

what do i do after i have the patch?

What do you want to do?

i am trying to close the bottom. 03 PM there a way to do that?

Yep. I would:

  1. Draw a closed outline of the base (like a rectangle), move it to the desired Z-level (below your terrain). This outline should be smaller than your Patch surface.
  2. _Extrude (from the solid menu) the outline to above the highest point of the terrain. This should create a solid block that fully intersects with the terrain surface.
  3. Use _CreateSolid with the surface and the block to mutually trim the two objects. Done.

select the surface and use the command bounding box with option solid. then call up trim and click on the parts which you dont need. join the rest together to make it solid again.

If the terrain surface is not axis-aligned or has irregular edges, you will not be able to trim. Also, this will likely leave you with a knife-edge at the bottom end of the terrain (if it does trim).


thank you guys so so much i really appreciate it. one last question i promise. so when i looked back at it i noticed that where the patch is didn’t drop at this one point it sort of just went down smoothly. is there a reason why it might not have done the drop and if so how can i make it do it? between the first black line and the green one
34 PM

thats for sure, but i believe that the curves where patched as suggested :wink:
additionally rotating the surface would not make sense.