Poor Quality of Drawing PDF

[Chris_Molland]

Hello

Using Inventor 2013 we have been creating very large prints (approximately 42" x 80") from our engineering drawings which are used for engineering review. We have spent countless hours trying to improve the image quality but still feel it falls short of our expectations.

Having created an engineering drawing everything looks spot on when viewing the drawing in Inventor. When you zoom in on a detail Inventor can redraw the area you are looking at keeping the geometry true to its form as described in the originating 3D assembly. No matter how much you zoom in everything looks great. For print we need to create a PDF version of the drawing, still vector so we thought it should be a good representation of the drawing. UNfortunately the PDF is a bit of an approximation of the drawing.

The best approach for us seems to be to create an Inventor drawing sheet which is as large as possible, say 40" x 80". From this we generate a plot file which, using Acrobat Distiller, we create the final PDF from. Simply saving as a PDF from Inventor is poor by comparison.

There are 2 key areas we are trying to improve:

1. Any line which is not straight becomes wobbly and distorted. Circles are not circular but a wobbly circular shape meaning that concentric circles overlap and don't make sense.
2. The shading has very stepped and jagged edges which do not fit the shapes they are filling.

These issues are mostly noticeable in the details but when the image is on a wall and you walk up to it you start to lack confidence in the accuracy of what you are looking at.

Inventor knows that a circle should be circular but it seems that when describing it as a vector line there is a resolution factor to take into account.

Can anyone suggest an alternative approach to create really crisp, accurate PDF files.

Many thanks.

Chris

[-niels-]

Sounds like it's mostly a Distiller problem.

Have you tried making custom setting for Distiller where you turn off all things related to compression and setting Dpi to something higher than the standard 600?
(mind you, this might end up giving you a huge pdf filesize.)

[Chris_Molland]

Thanks for the prompt reply.

Yes we have tried that thanks. We believe that the plot file which we are generating the PDF from is poor. We are using an HP plotter driver.

It appears that Inventor doesn't mathematically define the drawing in the plot file. It seems to generate a series of points, at a set granularity, and join the dots to create the vector lines. Only a small step up from a bitmap image!

As a comparison if I save an Adobe Illustrator file as a PDF it appears perfect in its form no matter how zoomed in I am.

[-niels-]

I've tried some things with Inventor's options for export, but none of the available formats seem to be better.
Shaded views will always be rastered it seems.

I did find a related topic which suggested a different pdf printer, though there was no accepted solution.
http://forums.autodesk.com/t5/Autodesk-Inventor/Printing-Inventor-Drawings-at-High-Resolution/td-p/3...

Maybe a merry-go-round of exporting to dwg and importing in Illustrator might yield results?
Though i fear for the rastered shading again...

[Chris_Molland]

Thanks for looking

You probably saw that it was me who posted the original question on the topic you suggested.

It may be that we have to import our Inventor drawing, or even assembly, into another CAD environment to create a better image. I will continue to explore different avenues.

Chris

[-niels-]

In honesty, i kinda skipped over the original poster so i didn't see it was you.

I did try some more exporting options and if you don't need it to be colored, then you can export to autocad dwg (setting options to older version, Acad 2004 for instance) and then import that directly into Illustrator.

It's detailed drawings you're trying to print, not just rendered images?
Otherwise you could try Showcase or 3DS Max.

[Chris_Molland]

Thanks for continuing to pursue this.

I will explore exporting to AutoCAD as a DWG to see how the image looks. We could, if needed, add the colour ourselves in Illustrator to help define different sub-assemblies. I don't think AutoCAD can open an Inventor Drawing, which would have been interesting.

Here's an example of a small piece from one of our PDF files:

It is drawings we require, not rendered images. They are mostly sections through plant. We almost want to define a section in Inventor and simply save the orthographic view out as vector artwork.

Thanks

[-niels- · Accepted solution]

In that case i think export to autocad dwg (not inventor dwg) with a version that Illustrator can handle (2004 works) and then using Illustrator's active paint tool for coloring might yield you some acceptable result.
It is a bit more labor to get it colored, but as long as there are no isometric views it should be pretty easy to do.

[Chris_Molland]

I'll give it a go and report back.

Thanks

[Chris_Molland]

We exported a drawing as AutoCAD dwg (2004) as you suggested and brought it into Illustrator CS6. It looks really promising.

Live Paint/Select could work well for adding colour. This is a really good development. Thanks.

We're now thinking about workflow and how we might organise our Inventor drawing and mapping to AutoCAD layers so that we can separate sub-assemblies to make colouring them easier in Illustrator. I can see how elements such as cross hatching are on separate AutoCAD layers so we could see if we could place individual parts/assemblies on their own layers.

Thanks very much. There's much to be explored here but I'll mark this as solved.

Chris