Ah useful to know! mm is the standard for architectural work over here in europe - avoids the misplacing of the decimal point i think! So yes many buildings are quite a few mm long. I will try working in cms or m. I don't suppose there is a way to override the moi acuracy for calculation to take this into effect? Just tried converting the model into cm and it works a treat - much faster and the file is down to 29mb. I like the way moi automatically scales your whole scene for you - would be cool to be able to scale the background images at the same time.

wow just rescaled up the model from cm to mm and the file size and resposiveness has stayed the same as if it was in cm. So could there be a way to turn down the sensitivity or become unit independant? Or maybe something that downscaled the object for the opperation and then rescaled it behind the scenes on completion? would you notice any difference visually to the model or run into problems with changing the resolution/accuracy?

Thanks for your help once again.