How to scale imported .obj mesh data

[kevfreemyer]

Hi all. First ever forum post here so bear with me..

I am working on designing custom car parts and thought it would be great to have a 3d scan of a vehicle for reference while modeling in Inventor. I had someone come out and do some scanning for me and they provided me with .obj files. I am able to open, import, place them in an assembly. My problem is converting the mesh data to inch format as opposed to mm. I have tried importing and saving, then derive with a scale factor but when I do this the mesh just disappears. 

I have searched quite a bit and really cant find any info on working with 3d meshes in Inventor. There must be a way to accomplish this...

Any help at all would be greatly appreciated!

Thanks

[johnsonshiue · Accepted solution]

Hi! It sounds like you are importing inch-based mesh. Although obj/stl is unitless, inconsistent units can be problematic. You can automatically scale the mesh by doing the following.

1) Start a new English based part (or go to Tools -> Document Settings -> Unit and change it to inch).

2) Import the obj file.

You should get the proper scaling. If it still does not work, please attach an example here , forum experts should be able to guide you through the process.

Many thanks!

[Anonymous]

Hello!

I've made several videos about mesh processing in Inventor but with stl (triangular mesh without texture). But I don't really remember anything about scaling mesh. If you still have trouble with it, I'll try to find it out

[johnsonshiue]

Hi! OBJ and STL files are unitless. The data stored in these files have not sense of unit. As a result, it is up to the importing CAD system to interpret what unit it should be. Usually, the common unit is mm. Occasionally, the mesh files are exported from an English unit-based design. In that case, 1 unit is one inch. The mesh is not necessarily scaled. It is more like the CAD system attach a unit to the data. For example, if you import a mesh file into an inch-based part file in Inventor, the geometry will be 25.4 times bigger than if you do it to mm-based part.

Many thanks!

[mcgyvr]

So you shouldn't need to do any scaling.. Just use the procedure posted by Johnson above..

[kevfreemyer · Accepted solution]

Thanks for the replies, guys. It turns out I was completely overlooking the fact that I could choose what units upon import via the options button. The scans were taken in meter format so all I needed to do was set that correctly upon import and it came in at the correct size. 

Thanks again for the help!

[n.sames]

Hey Johnson, I have a similar situation going on with a .stl file that I have uploaded to an assembly in Inventor. My scale is 25.4X too large. I ensured that the units of my assembly were set to mm before I dragged and dropped my .stl file into the assembly. Do you have any recommendations?
Thank you,
Nate

[n.sames]

Disregard. An Autodesk support technical specialist showed me how to do this. Thanks!

[c_bucataru]

Can you please tell us how to do it?

[johnsonshiue]

Hi! I assume the original mm model was exported to STL. Then you import to Inventor by using the default English Standard template so that it becomes 25.4 times bigger.

Try this. Go to Tools -> App Options -> Files -> Configure Default Templates -> select the desirable unit and standard. Import the same STL file again. Does it work better now?

Many thanks!