[LandXML] Re: Proposed attribute for surface faces
- From: Gordan Vosicki <gordan.vosicki@xxxxxxx>
- To: nathan.crews@xxxxxxxxxxxx
- Date: Mon, 03 Mar 2008 16:54:24 +0100
Hi Nathan and Hugh,
Sounds good to me, we already use such data in triangles.
An implied value of zero for the "b" attribute (i.e. make it optional)
would even reduce the data size overhead.
Best regards,
Gordan Vosicki
Nathan Crews a écrit :
Hi Hugh,
Sorry for the delayed response. I have discussed the proposal and it
would allow us to communicate better surface data with some processing
hints.
By using the new TIN face attribute, the importing application would
know which faces cross or lie on breaklines.
This is very useful information so we can add this last request to
LandXML-1.2 prior to finalizing that version. I will let everyone know
when the revised draft is posted.
Regards,
Nathan Crews
*From:* landxml-bounce@xxxxxxxxxxxxx
[mailto:landxml-bounce@xxxxxxxxxxxxx] *On Behalf Of *Woods, Hugh
*Sent:* Wednesday, January 23, 2008 2:02 AM
*To:* landxml@xxxxxxxxxxxxx
*Subject:* [LandXML] Proposed attribute for surface faces
<Surface> <Faces> <F> already has 2 optional attributes:
i="1" for an invisible face
n=adjacent face indices
I propose a new attribute to work with n :-
b=an integer bitmask sum of the sides of the face that had breaklines
in the original data.
This gives a range of 0 to 7 for TIN data: 1 for side 1, 2 for side 2,
4 for side 3.
For example b="5" has breaklines on sides 1 and 3.
A practical use of this could be for automatic assignment of
appearances to faces, recursively adding faces that do not cross a
breakline. There may be many other uses too, in combining overlapping
TINs while seeking to maintain breaklines.
The proposal would add very little bulk to the data, just 6 characters
per face.
Any support out there?
Hugh Woods
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