Digitising tablets

[kevin wooldridge]

If you intend to create polygons for GIS why not cut out AutoCad and go straight to ArcView or ArcGIS. You can scan plans, geo-reference the resulting bitmap or jpeg and then trace them. At the same time you can add relevant ID data to the attribute files. If necessary you can export the resultant shape files back as .dwg or in raster or vektor format or as data files in Excel or Access format. Cuts out the plotter.....saves loads of time.....I hate AutoCad....(sorry about the last bit)....

With peace and consolation hath dismist, And calm of mind all passion spent...

[BAJR Host]

Unit of One suggests the following

I have a A3 wacom but dont use it much- take a digi camera to take a pic of
plan -longish focal length put pic in coral and then vector it using mouse,
if it looks a bit off square play around with perspective or right clicks
pointy tool. Cut the whole drawing of plan stage out- take pic of
site-particularly sections and vector it .......


"Entrepreneurs are simply those who understand that there is little difference between obstacle and opportunity and are able to turn both to their advantage."
Niccolo Machiavelli

[BAJR Host]

http://www.bajr.org/BAJRResources/Software.asp

Here you can have a look at some Free GIS software.. and do what Kevin Suggests..
I would recommend QGIS (I have used this myself to create shp files with polygons)
http://qgis.org/

but look at this too for resources
http://freegis.org/?_ZopeId=86960740A2UIFG6Aku4

"Entrepreneurs are simply those who understand that there is little difference between obstacle and opportunity and are able to turn both to their advantage."
Niccolo Machiavelli

[chiz]

I think Kevin's idea of doing it in GIS is probably the most elegant method. I think the calibrate-digitise-polygonise/clean-export to GIS approach is a relic of pre-gis days, but I'd have to check with ex-colleagues about the history of the process and what they do now. Its a case of following the process you are happy with, instead of thinking afresh. As long as I can create the real/unreal parts plus the overall polygon quickly in GIS then that will be fine (I need the 'real' for the illustrations). I think I would still get a puck for the tracing.

I've got ArcView 3.3 and am happy using that, so should be fine. And the less CAD use the better, and I can then go straight from ArcView to Corel. Unless anyone tells me otherwise....


I wouldn't trust a digital photo to be accurate and not warp inconsistently, and to ensure it was 100% would be way too much faff, I'm looking at potentially several thousand plans....

I'm not sure where that leaves me looking for a A3 scanner...they are rather pricey too....but versatile for illustrations, and my A4 one is rather ancient. Any advice on choosing a good scanner!!

thanks for all the advice, it seems that from trying to get info about a redundant process, I should be actually stepping back, looking at what I want to do, and then re-thinking the process. So has been very useful indeed

[kevin wooldridge]

Regarding the A3 scanner...as you say you are intending to digitise single context plans is it possible to scan the relevant parts of the larger plans using your A4 scanner? It seems unlikely to me that a single context at a useful scale takes up the whole of an A3 sheet..

Maybe a little warning about 'old' computer hardware. I have recently had a similar problem to you Bob, regarding a scanner, an A0 plotter and a printer. I was offered all 3 pieces of equipment, unused, still boxed, as part of a 'clearout'. I provisionally accepted, but on closer investigation discovered that although the equipment was in fine working order:

1) I dont have a 16-hole socket on my current computer in which to plug any of this equipment and cant find a 16-socket/USB adaptor.

2) Windows Vista (which I hate even more than I hate AutoCad) would not allow me to upload/run any of the software that came with this equipment and I was faced with having to search through 'old programme' websites to try and find updated drivers.

3) In the end decided to use my old XP laptop to run the printer, but returned the scanner and plotter. But this does mean having to transfer files etc etc

Just might be worth checking those points before you get anything secondhand or reconditioned.

With peace and consolation hath dismist, And calm of mind all passion spent...

[BAJR Host]

GReat advice... and boy do I hate ACAD as well... like sewing with a sausage.. and about as pleasant

"Entrepreneurs are simply those who understand that there is little difference between obstacle and opportunity and are able to turn both to their advantage."
Niccolo Machiavelli

[ecmgardner]

ROFL... best description of CAD I've ever heard, and excellent idea on the GIS!

Unit of One's suggestion is interesting but you're better off getting something like PhoToPlan for CAD to rectify the photo which can rather handily be exported to scale as a Tiff. Used it to record the skeles at a cemetery site and so we cut out the planning of skeles in the field stage ('twas an interesting methodology!) Definite downside was, if the photo wasn't truly vertical you still get a distorted image even if it is rectified. A couple of the skeles looked like coneheads but for the majority it worked really, really well... took far less time, so the budget-meister was very pleased!

It's a cool piece of software (not cheap..!) and can be used for maps, plans and photos of buildings to remove all kinds of distortion (lens, perspective, parallax etc etc). I bought it a year or so ago and it has saved me SO many headaches. (http://www.theolt.com/products/pp/product.html)

[chiz]

Kevin, re necessity of A3 scanner for 5x5m single context plans, I agree. As you'll know 80% of SCplans are far less than A4, let alone A3, especially on truncated sites, so I guess a A4 scanner with stitching could work, although I'd be worried about distortion, it gets quite bad. I recently had to rescan a drawing (illustration, not plan) as the stitched A4 scans just didn't join up, the distortion was too great.
And I totally agree about old kit, by reconditioned I mean checked out, and warrantied, not a few quid off e-bay! The software issue was exactly why I wanted all your opinions. Its been useful to step out of the methodology I'm used to, and think of new ways to do the same process.

And looking around my 'office' I realise I don't have room for an A0 plotter.....

[Oxbeast]

Mount it on the ceiling, build a scaffold tower. Easy.

[chiz]

I think my daughter might mind, it is her bedroom after all.