Hi rhodsey, thanks for posting the file. Yes, this definitely works better to separate out just the few objects that are involved rather than the whole 46Mb file!

For a file that large you pretty much need to use one of those file sharing systems like divshare, or Windows Live Skydrive.

But anyway, I can repeat the problem over here - it seems to be related to the somewhat large size in units, your object there is about 10,000 units away from the origin. If you switch to meters instead so that you don't have quite as large of numbers, the chamfering will then work a lot better on that shape.

In general it is pretty good to pick a unit system that will give you numbers more in the range of 0 to 3000 or so and not a whole lot larger than that, because MoI will typically do calculations to an accuracy of 0.001 units, and if your object is of a large size numerically like 20,000 units across or something like that, then this accuracy is actually too high and you can get things like intersection curves with way too many points in them. That could probably be the reason for your large file size as well.

I'd recommend using Meters or centimeters instead of millimeters for something of this size. That will keep you in a better numeric range.

I'll take a look and see if it is possible for chamfer to be tuned up in this case, but you will run into various other problems when working with larger numeric sizes, so it is best to avoid that.

- Michael

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.

Hi rhodesy,

> I don't suppose there is a way to override the moi acuracy
> for calculation to take this into effect?

There isn't currently any way to override the accuracy level, but I do have some plans to try and make the accuracy more adaptive to the size of the model rather than fixed at one specific size. There are a couple of things that do this in v2 so far such as Join and Network. As time goes on I want to tune up more things to work in a similar way but it can tend to be a somewhat delicate area to mess around with.


> Just tried converting the model into cm and it works a treat -
> much faster and the file is down to 29mb.

What will probably happen also is that your file size shouldn't grow quite as quickly when you do some additional operations at the somewhat smaller size level, like booleans, etc... since those will generate less dense intersection curves.

I'm actually kind of surprised that it made much of difference right away.


> 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.

Oops, that is definitely an omission there! Yeah that would definitely be better for those to scale along with objects. I should be able to fix it up to do that in the next v2 beta. By the way you can disable the scaling if you wish by going to Options / General / Unit options / Scale on unit system change checkbox.


- Michael

Great thanks for the explaination and the scaling of images addition. Im working in cm now and things are running smoother. Think I should probably try working in metres though as many of our buildings are over 3000cm long. Cheers

Hi rhodesy, I was able to track down the chamfer problem to a bug in the geometry library, it was overly sensitive to some slight accuracy drift (like in the area of 0.000000000000001 units) that can occur when doing operations on curves that are a bit of a distance away from the origin.

I've fixed this up for the next v2 beta, so that chamfer will be able to work on your original curves there. But it is still a good idea to work in that new scale anyway to avoid that "dense intersection curve" problem currently.


I've also tuned up the unit system scaling to also apply to background images for the next v2 beta as well.

Thanks for reporting the problems and for posting the file so I could debug it over here!

- Michael