I'm working on a project that will be projected on a circular screen, hence need to apply a curve to the top edge of the video. (Three projectors, rear projected on to a cylindrical screen.)

I've done this successfully in Vegas Video (see http://www.villamil.org/itp/n360/cyclorama/12x3%20test-gradual.mp4), but need to do it in After Effects for higher resolution.

All the effects I've found in AE that seem to do this are very oriented towards local distortion - I can't find anything that does a simple smooth curve.

The Warp effect, using ArcUpper, is close, except that it squeezes the outer edges inwards as it applies bending. I need for the verticals to stay absolutely vertical throughout the warping process.

Mesh Warp looked promising as well, using 1 row and 2 column mesh, but the stretch is not evenly applied along the vertical edges.

The Vegas Lens Distortion effect did this perfectly, in one shot.

Any suggestions?

The reshape effect. Draw a rectangular mask the exact size of the footage, and duplicate it. Then convert the upper & lower edges of one of those masks to beziers, and curve them to your taste. The reshape effect will then accept those two masks as 'input' and drag pixels from the rectangular pattern up or down to match the bezier pattern. I don't know how 'accurate' it will be, but it's another option.

Yes, I'd try the reshape effect.

Thanks, Reshape looks very promising. Looks like I need to study up on editing masks...

Any Luck?

I finally got motivated to try this out myself.

Masking can be tricky, but the effect itself is also a bit particular.
The attached zip file is my AEP file, AE version 7.

I ended up using the Warp effect.

I'm in a situation where the amount of bending had to be adjusted a lot, and the Reshape effect needed a lot of work to get the corner pins to stay put.

Given the small amount of warping that I'm applying, the slight vertical "taper" effect that Warp creates wasn't a problem.