Strange curved shape

I'm working on quite a big personal (non-profit) project, but I'm having trouble re-producing a particular shape. The shape in question can be seen here:
http://img148.imageshack.us/img148/4562/curvedshapeho0.jpg

Ignoring the texturing and the circle in the middle, I'm hoping to build the basic shape of the "arch" at a size around 50m wide and 5-10m high (whichever is easiest).

My question is; does anyone know of a way to build this? I'm hoping to keep away from sculpties, and would like to avoid mega-prims if at all possible, besides which my thought for a mega-sphere cut appropriately would likely be hard to texture anyway due to the way textures are applied to spheres.

Any help/ideas are much appreciated!

I would say it's possible, using sections of a torus, ring or tube? but a hell of a lot of maths involved, and maybe the joins wouldn't make it look as smooth as you wanted.

50 meters wide AND 5-10 meters high ? maybe you mean 5 meters wide and 5-10 meters high ? that would make more sense to me... What is your basic problem ? In principle i would use a cylinder or a box and work with path cut and hollow, but if you need it smoother, maybe this tutorial helps a bit (although it is about sculpties ...): http://blog.machinimatrix.org/2008/06/16/the-arch-example/#more-17

I think he does mean 50 meters wide.

Nope. The ceiling is 50m wide, and the curving piece pictured should curve down 5 or 10m to join the walls. Hence the problem, the shape essentially is just the inside of a hollowed sphere, but mega-prim spheres aren't really detailed enough to make the curve look good (yeah I caved and tried one), they look too blocky =(

I'll try tubes etc. for now, thanks Gaia, I'll see how it turns out. In the mean time though, if anyone's built anything similar then I'm eager to hear how =)

That looks like distorted perspective to me. I think the actual arch is just a shape curved in one dimension.

The easiest way I know to make an arch is with a single box prim. Hollow it using a circle shape. Cut it in half. Stretch it until it's the dimensions you need.

The edges of the prim will penetrate the surrounding prims, in order to hide them and produce a smooth transition between the vertical surface of the wall prim and the inner curve of the arch cutout.

Go take a look at the window and door arches in the construction at the back lot of my site. See signature below for an arrival point, then fly uphill toward the temple.

Actually yeah a sphere would be the wrong shape, at the same time, a mega-prim cone distorts textures horribly when you taper them though. So in hindsight it's more like a 50-60m cone with height of 10-15m and unknown (10-20m) depth that's required, judging from my attempts so far and the scale of the rest of the build.

I may be able to build a convincing version from circular hollowed cubes and/or cones/cylinders as you seem to be implying, we'll see.

Looks like a hollowed cylinder with some taper or skew.

Looking at the picture's perspective, that's a stage, with walls extending at ~ 45 degree angles.

Taper or skew a hollowed cube with a circular hole and see what happens.

That gives me the shape I want, but not at the size I require. There don't appear to be any 50x20x10, 50x30x10 or 50x40x10m mega-prims available, and these are the only ones I can really make fit, ranging from shortest to tallest, though I suspect the 50x30x10 would be the best size.

I'm going to have a go at doing it in sections now.

MegaPrims for those sizes here.

http://www.slexchange.com/modules.php?name=Marketplace&file=item&ItemID=701196

Thanks Beverly that pack had the one I needed! Thanks to everyone that's tried to help, I really appreciate it!

For those interested, here's a pic of what I've been building so-far, everything is untextured except for the curtain which probably needs more work later on once the rest takes shape. It currently has no seats or balcony, and will have more boxes in the final version, plus a full stage and back-stage area, plus linking corridors up to the balcony/boxes. Will add an entrance hall if I have space when I get land for the building. I'm having to build it in sections due to prim constraints at my home location (where I build) so I can't show the full hall so far (not that the back is very interesting anyway):
http://img244.imageshack.us/img244/8467/operahousehu8.jpg

If you publish the parameters of your prim, i would give it a try and construct a sculptie for you with much smoother shape. It should also work with mega prims... Or you can send me a fullperm copy of your arch in world if you prefer ...