Cannot weld and cannot convert to editable poly

[Anonymous]

Hello everyone.

 I imported a file to 3ds Max from AutoCAD in .dwg format. I am trying to weld then try to convert to editable poly. But I did not manage to weld all the vertices and as you can guess I did not manage to convert the whole object to editable poly. 

 I select all the object then I weld but I cannot weld all the vertices. Approximately I manage to weld only half of them. So, I can only convert half of the object into the editable poly. When I select all part one by one(not to select all object) and I try to weld them I get "No vertices within weld threshold" message. I tried to change the weld values but nothing happened. All kind of help would be appreciated.

[Fadhil_Farook]

Can you upload some images or a screencast that would help us understand your issue better? Some faces could be flipped or something.

[Anonymous]

Thanks for the reply. I am actually modelling and airbase for Falcon BMS. This is the original version of the airbase :

This is after selecting the vertices:

If you look carefully you can see that some of the lines are yellow, some of them are white.

And this is after welding the vertices and editing to poly:

[Fadhil_Farook · Accepted solution]

If you're trying to make a sold object out of this spline, then you can use an EXTRUDE Modifier before you convert this to an editable poly. You can't convert a spline object into a 3D object directly without having any renderable geometry.

If you want like a wall instead of a ground out of this spline, you can use the SWEEP modifier instead of the EXTRUDE modifier.

[Anonymous]

Thank you so much Fadhil_Farook. I was not know that.