Photoetch artwork conversion - hard copy to dwg

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newport_rod
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Photoetch artwork conversion - hard copy to dwg

Postby newport_rod » Sun May 19, 2013 6:27 pm

I have some good old-fashioned manual artwork, drawn at 16mm/ft and measuring about 800mm x 400mm that I'd like to convert to a .dwg file so that I can modify it in AutoCAD. Any suggestions how I might approach it? I can scan up to A3 size if that forms any part of a solution.
Rod

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Martin Wynne
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Re: Photoetch artwork conversion - hard copy to dwg

Postby Martin Wynne » Sun May 19, 2013 7:00 pm

Hi Rod,

Scan your original, and then use image vectorising software.

That can be expensive, but the free version of Wintopo is very good: http://wintopo.com

To avoid giving any personal details, download Wintopo from: http://www.wintopo.com/dl-wintopo.htm

regards,

Martin.
40 years developing Templot. And counting ...

John Palmer
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Re: Photoetch artwork conversion - hard copy to dwg

Postby John Palmer » Mon May 20, 2013 1:31 am

Wintopo appears to be a very powerful vectorising tool.

Using the freeware version, I successfully saved a complete drawing using unaltered 'one touch vectorisation', but the default setting lent the vectorised output a sort of 'Mayan art' quality; it just picked up too many vectors!

Next I tried varying the vectorisation options to get round this. Appearance was much improved, indicating just how potentially powerful this software is. However, any attempt to save it thereafter resulted in warnings that I needed to buy a licence for £200 :o in order to save the entire drawing, and a sample area only would be saved via the freeware version. The sample area saved was very small, and I had no opportunity to specify what part of the drawing it would take in (in which case a mosaic of saved sections could have been stitched together).

Possibly the software switched into this behaviour because I applied an image processing option that's only available in the licensed version. but so far all my attempts to get back to the set of options that permitted saving of an entire drawing have failed.

Lots of promise, but unless you can get round the apparent freeware limitations this looks like a tool for the dedicated drawing converter who is prepared to shell out for a licence. Or is there some obvious switch to restore the freeware version's 'save' functionality that I have missed?

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Martin Wynne
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Re: Photoetch artwork conversion - hard copy to dwg

Postby Martin Wynne » Mon May 20, 2013 3:25 am

John Palmer wrote:Lots of promise, but unless you can get round the apparent freeware limitations this looks like a tool for the dedicated drawing converter who is prepared to shell out for a licence. Or is there some obvious switch to restore the freeware version's 'save' functionality that I have missed?

Hi John,

The freeware download also installs a free trial of the Pro version. If you use that (green icon on desktop), there is a restriction on the vectorised area which can be saved.

If you use the separate freeware version (orange icon on desktop), there is no such restriction.

They are two separate programs.

regards,

Martin.
40 years developing Templot. And counting ...

John Palmer
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Re: Photoetch artwork conversion - hard copy to dwg

Postby John Palmer » Mon May 20, 2013 7:35 am

:oops: Embarrassing not to have noticed that - thanks, Martin.

<edit> This may help to form an idea of Wintopo's capabilities.
K2 raster-vector-CAD.jpg
150 dpi scanned image of Roger Farrant's 7mm drawing of a K2 from March 1975 Model Railways. Processed through Wintopo Freeware with NO polyline reduction. Output from Wintopo as .dxf file, re-opened in DoubleCAD (also freeware) and re-scaled to 4mm : 1'. Image appears on my monitor about 10% oversize. The original scan was very slightly skewed, unfortunately.</edit>
Last edited by John Palmer on Mon May 20, 2013 8:10 am, edited 1 time in total.

billbedford
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Re: Photoetch artwork conversion - hard copy to dwg

Postby billbedford » Mon May 20, 2013 8:04 am

You can use vectorising software, but experience of any hand draw work suggest that just tracing over a scanned image is not only quicker but will give you a better result.
Bill Bedford
Mousa Models
http://www.mousa.biz

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newport_rod
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Re: Photoetch artwork conversion - hard copy to dwg

Postby newport_rod » Tue May 21, 2013 3:46 pm

Thanks everybody. I think I'll try tracing first but the vectorising software does sound useful.
Rod

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Flymo748
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Re: Photoetch artwork conversion - hard copy to dwg

Postby Flymo748 » Tue May 21, 2013 10:29 pm

newport_rod wrote:I have some good old-fashioned manual artwork, drawn at 16mm/ft and measuring about 800mm x 400mm that I'd like to convert to a .dwg file so that I can modify it in AutoCAD. Any suggestions how I might approach it? I can scan up to A3 size if that forms any part of a solution.
Rod


Coming to this a little late in the day, I can only add that my experiences confirm what you have found.

When I acquired 5522, I gained the phototools for the etches, but there was no original artwork, and of course this preceded the time that CAD systems were used to produce artwork files. For my own piece of mind, as the phototools are literally unique, I wanted to create some backups.

I researched this at length on the web, and there did not seem to be an easy solution. I didn't actually discover wintopo, so I may actually give that a try in future. From speaking to various firms, they all stated that to create a vector file from a drawing would be a very difficult process, and as you have found the resultant image has a number of minor errors that need manually correcting.

The other thing that I was warned about is that a lot of errors aren't visible to the naked eye, but become apparent when you "fill" blocks with colour to produce the two-sided artwork. A gap in a scanned line of only one pixel is enough to allow the colour to "leak" and fill the wrong parts of the image.

So the advice to me was very much to redraw the tool in a proper vector file. For me this was not necessary to start production. So what I have done is had a graphic design firm scan in some very high resolution files (saved as tiff or png, I can't remember) which will be the backup. If the phototools are ever lost, I'll just have to trace over them, as you have since found to be the best approach.

So I'm afraid that I have no knowledge that would be a revelation, but I can confirm that you are on the right track.

Cheers
Flymo
Beware of Trains - occasional modelling in progress!
www.5522models.co.uk

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Andy W
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Re: Photoetch artwork conversion - hard copy to dwg

Postby Andy W » Wed May 22, 2013 7:58 am

Again I agree with the re-draw solution. Drawing packages like Illustrator and Corel use paths (lines) and fills (blocks of colours). A shape can be formed by drawing a fill with a path around it or drawing a number of paths which are then joined and filled. When you vectorize a scanned line drawing you create a document with lots of shapes - not paths. As far as I know, these can't be joined to make a path. You can turn a path into a shape, but not the other way around. As a result you won't be able to fill between the lines. You would have to draw the fills separately.
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