AutoCAD to SketchUP - problems with curved surfaces

PRSS

Hello everybody!

I have my basic modelling done by a freelancer in AutoCAD (since SU is still
not so popular here in India) and then I import the model (ACIS solids) in SU
and I add more features etc. and then paint them with textures and then render
them in Kerkythea - which has become my favourite renderer.

The problem is all curved surfaces and circular objects imported from the DWG file
are heavily faceted. I have to pick each face to paint it with a colour/texture.
Quite often some circular surfaces get imported as broken entities with holes on
the surfaces which become very difficult to patch it up. The very idea of getting
the modelling done outside the office (to save time) gets defeated in the time taken
to patch up the surfaces when lot of circular surfaces are involved. Of course there
is no such problem when there are no curved entities.

I tried increasing the arc and circle smoothness in Acad with no improvements in SU.

Please kindly help me in solving the problem

Thanks in advance
PRSS

harnstein

did you check "merge coplanar faces" at "options" when you imported the file?

Anssi

If a CAD import misses faces, the reason is often that they are too small, the limit goes somewhere near 1 mm square. This can be helped by importing the file larger than the original (using, for instance, meters instead of centimeters for the impoty unit) and then scaling it back to the real dimensions.

Anssi

PRSS

Thanks for the replies. IMO I think I tried out all options for the circular
solid entities available in AutoCAD. Still the problem is there. es, I also
tried merge coplanar faces when importing into SU. That also did not work.
Looks like the only option is to do those curved objects in SU!

With best regards
PRSS

DzineTech

Indeed that was my understanding that all arcs/curves etc... get faceted upon import and there is no setting within SU whatsoever to let you specify the number of facets.

lapx

Is there a ruby script that would change the faceted edges into an arc or circle when selected? Or maybe su could maintain arcs and circles as just that. Is this an autocad problem not playing nice with SU?

Gaieus

There is a "weld.rb" which will create a single entity of a selection of (continuous) edges although it won't restore the circle or arc entity of exploded circles or arcs only creates a single entity polyline of them.

lapx

Thanks Gaieus,

I am aware of the weld ruby. I guess in order to turn an exploded arc back into and arc one would just have to trace over the 3 points again. I'm also assumming that there are cases where you want to keep an arc as an arc and not segmented lines or a weld of segmented lines.

PRSS

Thanks everybody. Tracing over the arc or circle is certainly the best way.
But if you have many curves, then you are doing them again in SU. So it
looks like there is no straight way of solving the import ACAD curves
in SU. I have to try out this Weld ruby.

Thanks once again
With best regards
PRSS

warburg

Hello from Italy
I have THE SAME problems........
SU toy-software???

bye

ecoto

I found a way that works pretty well.

You have to export your dwg to 3ds, to do this you have to download the 3DSOUT utility from http://usa.autodesk.com/adsk/servlet/ps/dl/item?siteID=123112&id=9481286&linkID=9240898, since they removed the 3dsout command from Autocad since release 2007, this utility works for all the later versions even though they claim only applies to the version listed there, i tried it on the AutoCAD Architecture 2009 release and it works fine. There you have on the readme file where you downloaded the utility the instructions for how to use the utility and to export to 3ds format.
When you have already loaded the utility on AutoCAD and you are ready to export to 3ds, on the 3d Studio file Options window, you have to select AutoCAD Object type on the Derive 3d Studio Objects from options, and uncheck the Auto-smoothing option, and then then AutoCAD starts exporting to 3ds. You have to do this because its exports forms, solids and other 3d objects in different ways.
Then you are ready to import to sketchup. Now you have a sketchup 3d drawing that works pretty well maybe you will have to applie some smoothing to some objects to get a very good appearance.

PRSS

Thank you ecoto for the link.

Wth best regards
PRSS

honoluludesktop

PRSS, For the purposes of material painting, consider organizing your CAD file so that these complex surfaces are blocks. SU will import a block as a components, which can be selected for painting all at once. Another advantage to doing this is if you edit the CAD block, it is easily updated in SU, and the original material can then be reapplied. Btw, I do this with DXF, and am assuming that it will work with DWG.

Jean Lemire

Hi folks.

Before importing any CAD file, check the "Merge coplanar faces" in the option. This will minimize unneeded triangulation.

SketchUp (SU) cannot close faces that have one or more edge smaller than about 1 mm or 1/16 inch. Import using a larger unit and scale down when done.

For curved surfaces that comes faceted, use SU smoothing/softening ability. Then it will be faster to put colors and textures on these faces instead of doing the facets one by one.

If the CAD file is sloppy, dont expect extraordinary results in SU. By sloppy CAD I mean:

Edges that dont touch in corners;
Edges that cross in corners;
Edges composed of many overlapping lines;
Non coplanar faces;
Etc.

I am writing this from experience since I have seen many drawings made with AutoCAD that showed one or more, if not all, of the abovementionned deficiencies.

SU is not a toy, even if there is a free version. However, like any other tool, it may produces bad results if it is used incorrectly or used outside its intended field of possibilities.

My experience with imported CAD files is to use them only as reference and to redraw everything from scratch, unless you are 110% sure that the CAD file was drawn correctly (ie. do not present any of the abovementionned deficiencies).

SU can import and export STL file with the use of a pluggin in the form of a Ruby script that is called SU2STL.rb.

Just ideas.

PRSS

Now-a-days I am not having much problem from autoCAD files imported to SU. Things are quite fine. There is also another trick which came from one of the forums - scale the AutoCAD model - say a 100 times. After importing into SU scale down by 100. You may even scale up to 1000 and then scale down in SU. This sorts out quite a lot of problems in curved surfaces. Also i have tried scaling up by 500 and then export as 3ds with Autosmooth turned off. Then import it in SU and scale down. Use the smoothing option in SU . This way it will be possible to pick the entire surface to apply texture.

With best regards
PRSS