How to Translate 10,000 or more EGS Archive Files into AutoCAD

    by
    Steve DiBartolomeo
    Applications Manager
    Artwork Conversion Software, Inc.

Users of Hewlett Packard's EGS (Engineering Graphics System) are now faced with converting thousands of files into another CAD format since the EGS system was obsoleted about 8 years ago and even the hardware that it ran on is reaching its end-of-life.

Artwork has taken our translation expertise and married it with our experience in handling large number of files to offer a service for the mass translation of EGS Archive to DXF files.

Getting Your Data

Just getting the data off of the EGS system may be a signigicant task. EGS ran on two distinct operating system: HP Pascal and HP UNIX.

HP Pascal - this proprietary operating system does not easily network with modern UNIX machines or PCs. The tape and disk format are also proprietary. The best method of getting a large number of files off of the Pascal machine is to write them to the proprietary tape format. Artwork maintains an old HP tape drive just for the purpose of reading these older tapes. HP UNIX - this variant of UNIX runs on HP 300/400 series workstations and supports such standard file transport protocols as ftp. Hard disks can be backed up in tar format - however the actual HP tape media cannot be read into other workstations. Again, we maintain an old HP tape drive just to read these tapes.

Getting from DWG to Archive!

What many users don't realize is that the egs2dxf translation only reads the archive format-an ASCII dump of the original EGS dwg file. To generate archive from an EGS DWG file you must open the DWG file using EGS and issue the archive command. The fact of the matter is virtually every EGS disk we've seen has only the DWG files saved on disk.

What this means is that if you have 10,000 DWG files on disk you will need to open a drawing, issue the archive command, wait while the program writes an archive file to disk, close the drawing and repeat the process 10,000 times....

On a slower and older CPU it may take 1 minutes to open a file and another 30 minutes to write out the archive file. Multiply this by 10,000 and you'll find that it takes an operator working 8 hours per day (with no bathroom breaks!) about 6 weeks to create all of the archive files and you've filled up 1000 MBytes of disk space.

"Surely this can be automated!" you exclaim. Not so. We've attempted to do so but discovered some type of memory "leak". If we attempt to do this from a macro (and we're talking about on UNIX - not on Pascal) EGS crashes after a few files. It appears that somehow memory is not properly freed up after closing a drawing so that after a few archives are written the system locks up.

Furthermore the archive file is more than twice the size as the original drawing file so on older systems with limited disk space there is no room for the entire set of archive files.

Our own solution is to run EGS on the fastest UNIX box we can attached to a very large and fast hard drive. We're able to load and archive the DWG files much quicker than most of our clients.

Libraries and External References...

EGS files are hierarchical - they can be built up from sub drawings. The sub drawings (or libraries as some call them) can be pulled into the drawing or the can remain external and are just referenced.

Referencing is more efficient but it makes translation extremely difficult. That's because when we go to translate a file we have to be able to get to the references in exactly the same place where they originally lived.

We can do this only by building a complete disk image of the original system with the exact directory and filenames. Whenever we quote a large job this is one parameter that must be defined because it makes a large difference in the amount of setup work. It also requires that we do the entire translation in one go - you can't do a small subset of the job under this condition.


Text - How Close Can You Come?

Our customers are normally very pickly about text - the new drawings should look exactly like the old drawings and all text should be placed exactly where it was before. It should also fit into the same location as before.

What makes this so difficult is that the actual font files are not transferred. EGS has its own fonts and AutoCAD has its own fonts. If the two fonts are not identical then the text in the new drawing will appear slightly different.

We can attack this problem in two ways. First, we can scale the text magnitude and width factor slightly during the translation. In some cases this gives good enough results. Second we can actually build custom AutoCAD font files (known as SHX files) that match the EGS font files. We've written our own in-house translator to do this. It's a bit time consuming but the results on the target drawings are indistinguishable from the source drawing.


Artwork Conversion Software, Inc. [Company Profile]
417 Ingalls St.
Santa Cruz, CA 95060
Tel (831) 426-6163 Fax (831) 426-2824
email:info@artwork.com

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