Strictures at an exhibition

In our art world ruled by curators, the 'consistency' of an artist's oeuvre has become a fetish. Fortunately, Mariele Neudecker's inventive works are breaking the rules.

In this age of unparalleled artistic freedom, there is one great controlling force - the rule of consistency. It's like a wish in fairy tale. The genie of culture says to artists: "Go ahead, you can do what you like, just whatever you like, but only on this condition - whatever you decide to do, you must always do the same kind of thing. You must find your focus - your look, or your trick, or your theme, and then go on repeating it with small variations until you and everyone else becomes heartily sick of it. For that's what it is, to be a serious artist."

In this age of unparalleled artistic freedom, there is one great controlling force - the rule of consistency. It's like a wish in fairy tale. The genie of culture says to artists: "Go ahead, you can do what you like, just whatever you like, but only on this condition - whatever you decide to do, you must always do the same kind of thing. You must find your focus - your look, or your trick, or your theme, and then go on repeating it with small variations until you and everyone else becomes heartily sick of it. For that's what it is, to be a serious artist."

Its effects you see everywhere. But this rule is a bad rule. It gets so that what we prize is not the work, but the overall oeuvre - something that can be called a personal "vision" or a quasi-academic "project". The single piece of art becomes a mere corroborating instance.

It was going to Mariele Neudecker's show, "Until Now" at the IKON Gallery in Birmingham, that brought this to mind. A very good show it is, I think, very inventive in its objects and ideas, very various actually. What I particularly like about it is that - unlike many contemporary solo shows - its effects aren't general. It isn't just "a convincing body of work". It wins at the level of individual pieces.

Which may seem an odd thing to say about Neudecker. The artist is Swiss-born, London-dwelling, in her mid-thirties, and if you know the work for which she's best known, you may think of her as very much an artist with a theme and a trademark. Her theme is landscape, especially Romantic landscape, especially German Romantic landscape. Her trademark works are meticulously fashioned miniature models of landscapes.

There are a couple of these in the show, and they're lovely bits of illusionistic craft. Displayed at about eye-level, these sections of terrain are contained in glass cases, which cut them off abruptly at the sides, mid-mountain and mid-tree. There's one with craggy alpine country, another holding a cube of deep forest. And these cases are filled up with liquid solutions, creating (chemically) a visible atmosphere. In the Alps, all the dips are lost in realistic low-lying mists. In the forest, the eye cannot penetrate into the central arboreal gloom.

So here is that self-contradictory genre, landscape-sculpture. To turn a view into a 3D, walk-round object is impossible. It becomes a boxed segment of land and air, a thing with sides and a top, no view at all. And matters of scale become bluntly real. Moving about it, you can't pretend these tiny mountains are seen from a great distance; they're just tiny mountains. (The mobile viewpoint is crucial - if these objects were seen from a fixed viewfinder, they'd be much more like pictures.)

And yet the form works. The eye can imagine itself down and explore these environments, and sort of lose itself in the experience. I can't go along with those who find these miniature landscapes actually uncanny, disturbing or dangerous (and goodness knows, I lead a quiet enough life) - they would have to be a good deal more realistic to have that effect. But surely they are fascinating.

There are other pieces in the show that you can, if you like, connect to these ones. For example, there's another model, a model of a shaft of light. It streams slanting down from a mini Gothic window, and it looks like light beams catching motes in darkness. But this shaft is not shining in darkness, and it is not light. It's made of a host of neatly plotted and threaded strands of (I guess) fishing line, like an old- fashioned exercise in perspective.

Then there are a pair of monitors, showing very close-up videos of a pair of eyes. When you stare into these eyes for a while you notice that in the middle of each dark pupil is reflected the image of a bright, distant waterfall, constantly flowing. The poignancy of the vision, of water falling inside the eye or the mind, is held in balance with the very precise and chancy angles of camera to eyeball to cascade on which its realisation depends.

And there's a large-scale video installation called Another Day. It was shot in May this year, and shows a simultaneous sunrise and sunset, as filmed from two opposite points on the Earth's surface, Ponta Negra in the Azores and Wilson Promontory in Australia. It is the same few minutes recorded on each screen, and (of course, but it seems to need saying) the same sun, rising from one viewpoint, sinking from the other.

The cosmic dimensions of this are clear in the telling. But actually, the piece offers more in concept than realisation. The two films are projected on opposite sides of the same screen, which hangs across the middle of a large darkened gallery; you have to walk from one end to the other and back, to view by turn the two events. And I see the point. That short walk represents a crossing of the globe.

But what this set-up prevents is the really miraculous potential of the idea: the impossible vision, simultaneously, of these "two" opposite suns. And besides, Another Day involves too much factual affidavit. There's no way it can make you see that the events are concurrent, or that its global vantage points are diametric. It could be any sunrise and sunset over any bit of southern sea.

A last piece, though, really proves itself to the eye. It can be simply described. It is a three-dimensional materialisation of the mysterious stretched-out image of a skull at the bottom of Holbein's painting The Ambassadors. The coordinates of a human skull have been taken, put through a projection programme, and cast in resin by a computer-sculpting machine. It makes a fragile, slanting, pulled-out object which sight can hardly grasp - though if you crouch and look straight up at its bottom end, it foreshortens into a skull in perfect profile.

And its title is a cracker - Divorced Beheaded Died Divorced Beheaded Survived, the school history mnemonic for the six wives of Henry VIII (Holbein painted portraits of three of them). It makes me think there should be an art prize just for titles, regardless of the attached work, and regardless of medium too, all arts competing together. Divorced Beheaded Died Divorced Beheaded Survived would be a strong contender. It could make a good title for a poem, an album or a dance.

And themes? Well, I can do themes as well as anyone. In Neudecker's work you can spot plenty: landscape, yes, and the relation of two dimensions to three dimensions, miniaturisation, illusions created and exposed, light rays, eyesight and viewpoints, perspective projection - and I don't deny they're good topics. But it's not the themes, the vision or the project that sustain the works. They perform - as I hope these descriptions show, piece by single piece, in their very distinct conceptions and technical solutions. And some pieces (or bits of pieces) succeed, and some (ditto) do not quite. And this is how an art exhibition should go.

Mariele Neudecker - Until Now: IKON Gallery, Brindleyplace, Birmingham B1; until 12 November, closed Mondays, admission free