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A
Anonymous
April 19, 2012
Question

Format of huffman compressed data in PRC compressed tessellation?

  • April 19, 2012
  • 3 replies
  • 8403 views

Hi there,

I've been looking to see if I can make our application create 3D pdf files using the PRC file format. I downloaded the PRC file format document from ISO and tried to read a few example files I found on the web to make sure I understood how it worked. It's all fine until I try to read huffman compressed data in a PRC_TYPE_TESS_3D_COMPRESSED section. The standard says that I should be able to read the huffman compressed data by using the opposite of the 'WriteUnsignedInteger' but if I do that I get invalid integers. If I try to read the unsigned integers by just reading 32bits directly the data doesn't seem to make sense if I try to decode the leaf data for the fuffman tree.

Does anybody know if there is any documentation on this or any examples? I'm at the point of giving up...

I'm a bit bewildered that there is an ISO standard but the example files that I have just don't seem to match it...

Any help would be be fantastic.

Thanks

Miles Thornton

This topic has been closed for replies.

3 replies

Félix110999055
Félix110999055
Participating Frequently
February 18, 2020

Maybe it's too late for you, but you should take a look at CrossCad/Ware SDK: CrossCad/Ware

T
Tarik Bureau
New Participant
October 30, 2013

Hi,

Are there any news about this topic  ??

M
mvid
Participating Frequently
May 18, 2012

Dear Miles,

 

while I can only share your bewilderment (I have also tried and failed to decode PRC_TYPE_TESS_3D_COMPRESSED),

may I ask you to clarify a bit what "PRC file format document from ISO" did you deal with - the old one avialable for free at

SC2N570-PRC-WD.pdf or the one currently being sold at ISO 14739-1:2014 ?

If you have got your hands on the latter, please, tell us if it is worth its price.

Is it an much improved relative to SC2N570-PRC-WD.pdf?

 

                               Sincerely, Michail

A
Anonymous
May 21, 2012

Michail,

I actually got the standard from BSi although I assume it is the same as the one at ISO. Here's the link to where I got it from. http://shop.bsigroup.com/en/ProductDetail/?pid=000000000030208200

The short answer is, no it's not worth the price at all. There are still errors in it from what I can see and (very annoyingly) it has 'DRAFT 2011' stamped across each page which makes it virtually impossible to select and copy any text from it using Acrobat.

On a different note I think that I am actually making some progress at reading the compressed tessellation. However I can only spare the odd day here and there to look into this so progress is quite slow...

M
mvid
Participating Frequently
June 30, 2012

Miles,

the number of pages of the current ISO draft is different from the one at bsigroup, so the text may not be the same.

Your text is called "BS ISO 14739-1", while ISO draft is "ISO/DIS 14739-1.2", that "2" may indicate the next iteration.

On the other hand, it seems a new dratf (1.3) is coming in August:

http://www.techsoft3d.com/developers/article/prc-iso-update

http://www.pdfa.org/2012/06/iso-standards-pdf-week-in-mississauga/

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