# Interpolate mesh surface between curves

Suppose I'm trying to model a curved surface: the roof of a car is a perfect example. Many tutorials suggest creating a plane mesh, which I should subdivide via loop cuts, and then proceed to model the mesh in two dimensions (say from the top, so X and Y). After that, I switch to a front or side view and I move the outer vertices along Z.

Here comes the tricky part: I end up with two "edge curves", two outer profiles of my surface. Say we're looking at a side view, so the Y axis is along the horizontal axis of the screen. How can I move a "row" of vertices (vertices that share their X coordinate) or multiple rows so that they fit the smooth transition from the "back" profile to the "front" profile?

I know in a sense this sounds like lofting - it probably does, but I'm not sure I get the concept fully. However, I'm looking for something that I can apply at will, not only when creating and developing a surface. In other words, if I move a vertex of one of the "profiles", I want to be able to reposition the inner vertices smoothly based on the new position of the outer vertices.

EDIT

Here are some screenshots to help you understand what I mean.

Here's a plane mesh, with subdivisions in (supposed) key points. I move the outer vertices to match the surface I'm modeling. This is still a flat surface, but you can already see what I mean: I want the inner vertices (those still lying on the square grid) to be moved so that the rows transition smoothly from the curve of the top row to the curve of the bottom row. The "columns" should do the same.

In this second screenshots, the outer vertices have also been moved along the Z axis. You can see what I mean by "smoothing the surface": the inner vertices should follow a curve so that the surface is smooth.

• I should also add that this is similar to what the loop cut actually does. But I need to do it "after": I already have the inner row of vertices, I want to move them in the position the loop cut would put them into. I hope this is clear. – Simone Jul 29 '15 at 20:19
• Maybe add a few screenshots? – Todd McIntosh Jul 29 '15 at 22:48
• You can hold the (Alt) key and then select a vertex and whole edge through out all the mesh (depends on how good your topology is) will select – Igor Tatarnikov Jul 30 '15 at 7:58
• Kinda like the Loop Cut tool does. In this two screenshots (i.stack.imgur.com/47xzY.png i.stack.imgur.com/Ax8hu.png) you see the edge the toold would add in different positions. Notice how the position of the new vertices is interpolated based on the nearest edges. – Simone Jul 30 '15 at 10:19
• It seems you're looking for Proportional Editing (press O in 3D View window) feature. You can also set up its editing modes after turning it on – Mr Zak Jul 30 '15 at 10:21