I have produced a number of Therion models which are viewed using Loch. I have to say that I am tremendously pleased with the visualisations that they give. However, we always want something more, don't we. One of the extremely useful features is the ability to drop surface data and maps on top of the model, making it possible to check the relative positions of underground and surface features. One of the limitations of this, though, comes with the resolution of the surface image. (there is a further limitation with the resolution of the open source DTM data but there is nothing that we can do about that.) This is not much of a problem with most models but one of mine covers an area of 30 km x 30 km. That means that any jpeg that covers the whole area will not be of a suitable resolution to show detail when one zooms in on smaller parts of the area. What is needed is a 'Google Earth' type system whereby the jpegs can be 'swapped' as one zooms in. Don't tell me to generate kml files and use Google Earth, as that loses the 3d capability. I'm sure we have the computing power to deal with files of the size that this implies. I'm also sure that it'll take a deal of fancy programming to implement. If I had the skills I'd give it a go. I don't, so I can just hope that someone with the relevant skills will take the job on. What I can keep doing is working on the mapping agencies to release suitable data. I shall do that, even though I've had little luck so far. Graham -- graham.mullan@coly.org.uk 0117 9502556 or 07887 637064 (or 0844 2327803)