Nurbs Curve length?

I know with the Bezier curve you are able to get the length of total length.

Is it possible to get the length of a Nurbs curve?

1 Answer

Measure the length of a curve/path. (straighten out) -

A simple, albeit crude method would be to -

Set the viewport's view mode to Ortho and from the top. (Numpad 7)

Duplicate the (curve/path) and move it into a spare layer/collection.

Go to that layer/collection and select the duplicate. APPLY it's scale. (CTL-A) If it's got any animation or constraint working on it, get rid of them.

Set the cursor to location 0,0,0 with SH-C then set the curve to the 3D cursor. (SH-S)

Add a cube. It will also appear at 0,0,0.

Scale it down so it's small enough to travel along the curve. Apply the scale.

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For increased accuracy you can also do this - (but do it later. Jump to below the animation)

Select the cube and in Edit mode add an edge that spans two diagonally opposite corner vertices. Sudivide that edge. An extra vertice will appear in the center of the cube. Select that and set the 3D cursor there. (SH-S)

In Object mode add a mesh -> circle and scale it down so it's a small circle at the center of the cube. Apply the scale. (CTL-A)

Parent it to that center vertice with CTL-P.

The circle won't have any surface which is what we want.

The cube is going to get deformed whereas the circle won't. In theory that should enable you to more accurately position the cube dead center over the curve's far end.

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...To Continue - with or without the circle

Select the Cube and give it a curve Modifier. Use the Nurb copy. The cube (and circle/dot) should appear at the exact start of the curve. Zoom up to maximum to see this in wireframe view. Make sure you're still in Ortho -> Top view.

With the cube still selected, pull it's Gismo along the X axis (or whichever axis works). Take it to the other end of the curve. Zoom up as far as you can to make sure it's right on the end. Observe the circle to more accurately establish this.

Read the cube's X axis location in the Viewport's Properties --> Transform.
That will give you the length of the curve because the cube's OP started from location 0,0,0 .

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The accuracy can be tested by adding a straight curve - a path, and comparing it's physical length in Ortho view to the distance the cube travels.