exported DWG file size

[jeromeguertin]

Hi everyone,

 

first post here!

 

So here is the problem: We always export dwg of 2d splines from max to autocad for our cad guy here at work.

 

But we had complaints that our dwg where too big in files size..

 

We did a test: Exported a dwg from autocad ( 225ko ) then imported in 3dsmax and re-exported from max the same un-touched file and its now like 2 mb.

 

So max is putting more informations into the splines then autocad, thats normal i think,

 

but once re-imported in autocad if you re-export the dwg it keep max's informations so the dwg exported from autocad is heavier now...

 

Is there a way to export those 3dsmax splines with a smaller size? With just basic informations that autocad needs and thats it. I've searched for a script with no luck.

 

And sorry i had a hard time putting this problem / question into words! I can explain further!

 

Any ideas?

 

Thank you.

 

Jérôme.

[erickdt]

What's happening is MAX is facetting smooth curves from AutoCAD. Everything in AutoCAD is vector based, including curved lines. That is to say that every line you draw is based on a mathmetical function. Think back to highschool and plotting graphs based on sine, cosine, etc. That's the same basic system used by AutoCAD (and all vector based applications such as Adobe Illustrator, etc.)

 

Now MAX doesn't work that way. MAX breaks everything down into facted lines and triangles and uses a smoothing algorithym to make them appear smooth. Think about when you import an AutoCAD drawing into MAX. There are settings in the import dialogue where you specify to what extent you want MAX to facet the curves. All of that said, those faceted curves are made up of a series of straight lines. In order to describe a line in 3D space they still have a vector function based on a mathmatical equation. So now your curved line that had been described by one equation is made up of several lines, each of which have their own equation. Each equation takes up bits so the more you have the larger your file size is.

 

So, when you import a drawing into MAX is facets curved lines. When you export from MAX, those faceted lines are what is exported containing the same amount of data resulting in a similarly sized file...

 

Hopefully that makes sense.

 

E

[jeromeguertin]

Hi Erick thx for taking the time to reply.

 

We finally found the problem with our stuff, our lines in 3dsmax wher exported from solidwork at the begining thus made them really heavy for nothing!

 

But to add to your infos, you said that when exported from max lines are supposed to be the same size or so then the autocad ones. But if we export some lines from autocad, then importe in max then re-export from max then the file size is bigger just because it went into max.

 

So here, its not similarly the same size, weird.

 

But anyways at least we've found where the huge file size came from,..messed up shapes with way too much vertex for nothing. eh

 

 

Thx again!

 

Jay.