Possible bug in C360 volume calculations

[dhaverstick]

I have an Inventor model that is uploaded into C360 and I noticed a discrepancy today between Inventor and C360 when they displayed the volumes for certain parts in the model. 

Here is a screen shot of the volumes reported by Inventor for the model.

Here is a screen shot of the volumes reported by C360 for the same model configured the same way.

Can someone please explain to me why there is a discrepancy? This is a very big deal to me because the C360 application that I'm writing is a volume calculator.

Darren Haverstick

Paul Mueller Company

[dhaverstick]

Okay, since nobody wants to help me with this, I did a little more research on my own. I made an assembly of two sphere halves to create a sphere. I created some parameters and iLogic rules to calculate the volume of the sphere and output the value in cubic inches, gallons, and liters.

Below are a couple screen shots from the Inventor assembly and the same assembly loaded into C360. The sphere has a radius of 100 inches. It appears that the problem has to do with whatever calculation both pieces of software do to convert the value given by iProperties.VolumeOfComponent("ComponentName:1") to gallons. The volume of a sphere is (4/3)*PI*r^3. Both Inventor and C360 match the volume calculated by hand using cubic inches and liters. Neither match the theoretical volume value for gallons (18133.2909298). What is more disturbing, though, is that they do not match each other.Inventor screen shot

C360 screen shot

I have spent a lot of time developing a C360 app that calculates the volume of some of the products my company makes. These volumes can be quite large so the discrepancies between what C360 calculates and what I calculate mathematically are noticeable. I guess I can go back and change my C360 model parameter units from gallons to liters or cubic inches but I shouldn't have to. Can some admin please take a look at this issue and get back to me?

Thanks,

Darren Haverstick

Paul Mueller Company

[Jon.Balgley]

Hi Darren --

Thanks for looking at this more closely.  Can you send me your two-half sphere model, or a link to it on C360?  Thanks.

--Jon

[email protected]

[dhaverstick]

Well, we're waiting on the official Autodesk confirmation, but it appears the conversion factor used to report gallons is incorrect in both the 2018 and 2019 code. Also, the conversion factors used are different for 2018 and 2019 which explains why I was getting different answers between my Inventor model (2018) and the C360 model (2019). 

To get around this issue, I changed all my volume parameters to be unitless and had the values returned as cubic inches. I then did the conversion to gallons, or whatever, in my web page code.

This is some pretty sloppy coding, Autodesk. I really expect better from you. FYI, the conversion factor from gallons to cubic inches is 231 and gallons to cubic centimeters is 3785.41. 

[MjDeck]

There was a typo in the conversion factor in the 2019 release. We have the fix ready to go in a future release. The internal defect number is INVGEN-19016.