cgmo-webcgm message

Subject: Re: AW: Regarding CGM File Format

From: Lofton Henderson <lofton@rockynet.com>
To: Dieter Weidenbrück <dieter@dwz8.de>, "'Tarun Batta'" <tarunbatta@gmail.com>
Date: Sat, 19 Jan 2013 14:09:00 -0700

Good points, Dieter.

I was mainly looking at and thinking about simple WebCGM content instances, i.e., the metafiles (CGMs) themselves. And also ignoring embedded compressed raster content that might be integrated with the vector content.

-Lofton.

At 06:57 PM 1/16/2013 +0100, Dieter Weidenbrück wrote:

All,

we should probably mention some of the more complex features of WebCGM
-        WebCGM DOM (enabling manipulation and animation of objects)
-        XML Companion file to hold meta data related to objects
-        Zipped CGM files

And, more basically, a reference to the widely used hybrid files containing vector and raster (JPEG, PNG, CCITT T.6) data.

Regards,
Dieter

Von: Lofton Henderson [mailto:lofton@rockynet.com]
Gesendet: Mittwoch, 16. Januar 2013 18:27
An: Tarun Batta
Cc: Don Larson
Betreff: Re: Regarding CGM File Format

At 10:47 AM 1/15/2013 -0800, Tarun Batta wrote:

Hi Guys,

@Lofton: Thanks for your reply. It will certainly help me a lot.

No problem, you're welcome.

@ Don: It would be great if you could throw some light on the encoding programs which Lofton mentioned.

Also, few more queries from my end,
1) Please point me to some spec sheet which explains the jagrons (elements, entities and properties etc) used in Clear-Text format.

Right now, nothing comes to mind other than:

a.) the standard itself -- links below to part 1 & 3, link here to part 4 (clear text):
http://standards.iso.org/ittf/PubliclyAvailableStandards/c032381_ISO_IEC_8632-4_1999(E).zip

b.) or the out-of-print "The CGM Handbook", Henderson & Mumford, Academic Press.

You might find one of the older, "survey" papers helpful, listed here:
http://www.cgmopen.org/webcgm/readings.html

Maybe Don can think of another resource... Don?

2) For what I know that CGM files are interactive (have hyperlink navigation, hotspots, screentips on objects, etc.). Therefore, In addition to rendering the CGM file on the browser what other features are most important to be addressed. For example, with MetaWeb plugin for IE, one can perform operations like zoom, pan, rotate, resize, highlight hotspots, introduction of shapes (like lines, polygons etc), editing, etc.

Other than hyperlinking (and its associated behaviors like highlighting the target), there is not much more interactivity that is *implicit* in the CGM elements themselves. But as you point out, there are lots of useful interactive features (zoom, pan, highlight, edit, etc...) that are offered in viewers as what I'll call "sensible product features".

Don, any further comment on this?

The following will give you guys an overview of my approach,
Problem Statement:Â Currently to view the CGM files on browser we need to have a plugin installed but the same restricts the user to a certain browser. For now, there is no solution by which we could render CGM files on any browser of our choice.
Solution:Â I am working on a client side framework which support all browsers. The end user doesn't have to install any plugin on his/her system. Also, the framework could be scalable so that new feature-sets could be incorporated on the fly.

P.S.: I hope you guys would entertain more queries from my end in future as well.

Sure, no problem. Keep asking.

Question. Do you want your questions shared with slightly larger group of CGM activists/experts of the WebCGM Technical Committee? If "yes", you can tell us so and we'll "Cc" to that group. Or else you could use the public "Comment" button here:
https://www.oasis-open.org/committees/tc_home.php?wg_abbrev=cgmo-webcgm

Regards,
-Lofton.

On Tue, Jan 15, 2013 at 8:25 AM, Lofton Henderson <lofton@rockynet.com> wrote:

Hi Tarun,

I'll be happy to answer your questions, to my best ability.Â (If I can't, I'll turn you over to others.)Â I notice that you have been communicating with Don Larson also on the LinkedIn thread, so I'll copy him here.

At 12:50 PM 1/14/2013 -0800, Tarun Batta wrote:

Hi,

I got your contact details while trying to fetch information regarding CGM.

Currently, I am in process of developing a framework for WebCGM. It would be great if you can take out some time to answer few of my questions.

The following are queries,

1) The CGM files could be in 3 formats namely binary, character-set and clear-text.

Actually, the 2nd encoding -- Character -- has been dropped from the official ISO (and ANSI) standard for some time.Â (Mid-90s, as I recall.)Â So that's a piece that you can ignore.

In order to write a library I am thinking to convert binary and character-set format to clear-text. After the conversion, I can write a parser which can draw the images by reading the clear-text CGM instructions. So, in this what are the binary and character-set CGM formats and how can i convert that into CGM.

You can find the Binary format described in Part 3 of the ISO standard -- ISO/IEC 8632-3:1999:

http://standards.iso.org/ittf/PubliclyAvailableStandards/c032380_ISO_IEC_8632-3_1999(E).zip ,

which you can find on this page with the other CGM (8632) parts:

http://standards.iso.org/ittf/PubliclyAvailableStandards/index.html

Binary-to-ClearText is a good strategy to get something easier to work with.Â E.g., I have done it so that I could do simple edits, then convert back to Binary for legal interchange (under profiles like S1000D).

There are programs available to do these encoding-to-encoding conversions.Â For example my former CGM software company had such a program, that is probably still available somewhere in the world.Â I'm sure that Don can help you here, also.

Is this a good approach, or would you suggest anything better?

Without completely understanding your end-goal, I'll venture ... yes, seems like a sound strategy.Â Don, do you have anything to add, or am I missing some point here?

Regards,

-Lofton.

Looking forward to hear from you.

Thnaks & Regards

Tarun