merging ECW files to be draped on surface

[abrooker]

I have 25 ECW on a 5x5 grid. Each ECW file is 3x3 km making the complete site 15x15 km (each ECW file size is 15-25mb).

I need to merge them all together so I can drape them on a surface for presentation purposes and hopefully pull a few renderings from it.

Anyone have any adivce on what file image type is best to use for this? Also any advice on how to pull this off would be much apprieacted.

Thanks!

Adam