Pen plotter as digitizer
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From: D Yuniskis on 16 Dec 2009 16:54 Hi, It is possible to use a pen plotter as a digitizer (accuracy may not be as good as a large tablet but an E size plotter takes up far less space than an E size tablet! Trust me, having had *both*! :< ) Skip the HPIB interface (HP Pen plotter. HPIB sucks) but the EIA232 interface should be more than adequate. The format of packets is described in the HP service manual, etc. But, has anyone ever *done* this? I've never seen software on the receiving end of this process. And, a tool to bring it into something useful (e.g., AutoCAD). Google has been no help. And, none of my AutoCAD manuals (going back to v11) say much about it. Is this something I have to write myself? I suspect it would have to be interactive as I can't imagine how you could tag each point's significance, otherwise. (ideally, you would want to be able to treat the pen plotter as yet another pointing device and use *it* within AutoCAD). Pointers appreciated... --don
From: Bit Farmer on 16 Dec 2009 17:07 D Yuniskis wrote: > Hi, > > It is possible to use a pen plotter as a digitizer > (accuracy may not be as good as a large tablet but > an E size plotter takes up far less space than an > E size tablet! Trust me, having had *both*! :< ) > > Skip the HPIB interface (HP Pen plotter. HPIB sucks) > but the EIA232 interface should be more than adequate. > The format of packets is described in the HP service > manual, etc. > > But, has anyone ever *done* this? I've never seen > software on the receiving end of this process. And, a > tool to bring it into something useful (e.g., AutoCAD). > > Google has been no help. And, none of my AutoCAD manuals > (going back to v11) say much about it. > > Is this something I have to write myself? I suspect it > would have to be interactive as I can't imagine how you > could tag each point's significance, otherwise. (ideally, > you would want to be able to treat the pen plotter as > yet another pointing device and use *it* within AutoCAD). > > Pointers appreciated... > --don The HP 7475 plotter actually had this as a function. Instead of a pen, you could place a plastic lens and the press one of the keys and the HP-GL co-ordinates would be sent over the RS-232 ports. Look for a download of the manual. They should be out there. If not, I have the manuals for both the 7470 and 7475 on the shelf. b. Farmer
From: Bit Farmer on 16 Dec 2009 17:22 Bit Farmer wrote: > D Yuniskis wrote: >> Hi, >> >> It is possible to use a pen plotter as a digitizer >> (accuracy may not be as good as a large tablet but >> an E size plotter takes up far less space than an >> E size tablet! Trust me, having had *both*! :< ) >> >> Skip the HPIB interface (HP Pen plotter. HPIB sucks) >> but the EIA232 interface should be more than adequate. >> The format of packets is described in the HP service >> manual, etc. >> >> But, has anyone ever *done* this? I've never seen >> software on the receiving end of this process. And, a >> tool to bring it into something useful (e.g., AutoCAD). >> >> Google has been no help. And, none of my AutoCAD manuals >> (going back to v11) say much about it. >> >> Is this something I have to write myself? I suspect it >> would have to be interactive as I can't imagine how you >> could tag each point's significance, otherwise. (ideally, >> you would want to be able to treat the pen plotter as >> yet another pointing device and use *it* within AutoCAD). >> >> Pointers appreciated... >> --don > > The HP 7475 plotter actually had this as a function. > Instead of a pen, you could place a plastic lens and the > press one of the keys and the HP-GL co-ordinates would be > sent over the RS-232 ports. > > Look for a download of the manual. They should be out there. > If not, I have the manuals for both the 7470 and 7475 on the shelf. > > b. Farmer To answer your question, more specifically, we did do this. And at one point we investigated replacing the gun sight with a photo receptor and digitizing the contrast changes. We slewed the pen across the paper side to side and then advanced it an amount vertically. (More than one step due to image field size) The ultimate goal was to digitize and reconstruct schematics from copies of circuit boards. b. Farmer
From: D Yuniskis on 16 Dec 2009 17:30 Bit Farmer wrote: > D Yuniskis wrote: >> Hi, >> >> It is possible to use a pen plotter as a digitizer >> (accuracy may not be as good as a large tablet but >> an E size plotter takes up far less space than an >> E size tablet! Trust me, having had *both*! :< ) >> >> Skip the HPIB interface (HP Pen plotter. HPIB sucks) >> but the EIA232 interface should be more than adequate. >> The format of packets is described in the HP service >> manual, etc. >> >> But, has anyone ever *done* this? I've never seen >> software on the receiving end of this process. And, a >> tool to bring it into something useful (e.g., AutoCAD). >> >> Google has been no help. And, none of my AutoCAD manuals >> (going back to v11) say much about it. >> >> Is this something I have to write myself? I suspect it >> would have to be interactive as I can't imagine how you >> could tag each point's significance, otherwise. (ideally, >> you would want to be able to treat the pen plotter as >> yet another pointing device and use *it* within AutoCAD). >> >> Pointers appreciated... >> --don > > The HP 7475 plotter actually had this as a function. > Instead of a pen, you could place a plastic lens and the > press one of the keys and the HP-GL co-ordinates would be > sent over the RS-232 ports. Yes, that was my whole point. It is common on *most* (all?) of the HP plotters. Getting the data from the plotter is easy -- the plotter *gives* it to you! The problem is getting that data *into* something (e.g., AutoCAD) where it can be of use. I can write a small routine to collect the incoming data from the serial port. And put it in a file. Big deal. Now I have a bunch of (X,Y)'s but no *context*! I.e., if digitizing traces on a PCB artwork, how do I know which "points" belong to each "foil"? Which points represent pads and which represent "corners" of traces? Etc. If digitizing blueprints for a house, how do I know which points belong to each "wall"? Sure, I could import all of the points into AutoCAD and then play "connect the dots" -- and *hope* I connect them properly. :-/ I need to be able to replace the tablet driver with a penplot driver, so-to-speak. But, since HP made a point of including this feature in their plotters *and* since large format digitizers were expen$ive during the pen plotter era, one would think there was a mechanism already in place to use this data! > Look for a download of the manual. They should be out there. > If not, I have the manuals for both the 7470 and 7475 on the shelf. I have service manuals for all of the pen plotters. As I said, they haven't been helpful. Nor has the AutoCAD documentation (I didn't keep any of the documentation for releases 10 and earlier -- though I think I still have some version *2* floppies somewhere around here :-/ )
From: Bit Farmer on 16 Dec 2009 17:35 D Yuniskis wrote: > > I can write a small routine to collect the incoming data from the > serial port. And put it in a file. Big deal. Now I have > a bunch of (X,Y)'s but no *context*! I.e., if digitizing > traces on a PCB artwork, how do I know which "points" belong to > each "foil"? Which points represent pads and which represent > "corners" of traces? Etc. > > If digitizing blueprints for a house, how do I know which > points belong to each "wall"? > > Sure, I could import all of the points into AutoCAD and > then play "connect the dots" -- and *hope* I connect them > properly. :-/ I need to be able to replace the tablet > driver with a penplot driver, so-to-speak. > > But, since HP made a point of including this feature in > their plotters *and* since large format digitizers were > expen$ive during the pen plotter era, one would think > there was a mechanism already in place to use this data! In our work, the reconstruction of the image was the hardest part. First attempt was to build a follower. We would advance in the direction that maintained the contrast. This sort of worked, but failed when we hit Tees and branches. Since we were rasterizing the data, we ended up just building a row and column matrix that held the contrast values. Once a section was done then we could follow the traces in data matrix. This was in the early/mid 80's and because memory was expensive, we could only do small sections. I would be kind of fun to recreate that. b. Farmer
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