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Subject: [OASIS Issue Tracker] Updated: (OFFICE-2200)draw:extrusion-first-light-harsh [N 1309]

     [ http://tools.oasis-open.org/issues/browse/OFFICE-2200?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Dennis Hamilton updated OFFICE-2200:

        Fix Version/s: ODF 1.0 Errata CD 5
                           (was: ODF 1.0 Errata 03)
    Affects Version/s: ODF 1.0 (second edition)
                       ODF 1.0 Errata 02

**** A BIGGER ISSUE ***  

There seems to be enough information to treat the default point sources provided for in 9.5.2.  What is not specified at all is the consequence of specifying that one or both of the sources are NOT HARSH.  There is no account for what is expected in those cases.  Harsh lighting is the easier case and it is the default.  Knowing what NOT HARSH involves is a bigger issue.

I can't argue with the fact that current ODF 1.2 committee drafts also expect that "harsh light" is understood and don't bother to assert that it is as if from a point source (which if so well-defined, we should have been able to simply say).   The more-serious omission with regard to what it means to be non-harsh would seem to apply there too.  

**** MORE DETAILS ****

It appears to be understood that that harsh light is that from an undiffused point light source.  For example, direct sunlight on the Sahara at 11am under clear skies is considered pretty harsh.  The same is true on ice, snow, and at sea under bright daylight conditions.  At solar distance, it might as well be a point light source.

Most of the material I find is not about creating harsh lighting, but about diminishing its effects in photography and in digital photograph manipulation. Causing the appearance of harsh lighting by applying digital-darkroom techniques to a softly-lit image is actually quite involved.

If you look at standard search results such as http://www.bing.com/search?q=harsh+lighting+computer+graphics&mkt=en-us
you'll see that most use of the term is in how to avoid or overcome harsh lighting.  It is understood what it is, but there doesn't seem to be much on how one would instruct a computer-graphic system to cause it.  In fact, the flaw of most computer graphic simulation of lighting, historically, was that harsh lighting was the only lighting available.  It is the easy default (as apparently for ODF 1.2 custom graphics too).  Digging deeper, I find that the challenge in computer-graphics is avoiding harsh lighting, just as in photography.

From those sources, one can find consensus that harsh lighting results from individual point light sources.  To know its effect, apparently one must ascertain the intensity, the distance, and the assumed line of sight between the point source (if outside of the scene) and the illuminated scene.   The effect has to be integrated with the effect of other light sources on the scene, transluscence in illuminated objects, etc.  

Reviewing section 9.5 and 9.5.2 in particular, there appears to be considerable information on position, intensity, and so on.  There is not a lot on how this interacts with provisions of 9.4 around lighting (especially ambient lighting), if at all

Apparently harsh light is not so much a well-defined term in computer graphics as much as it is the common default.  Non-harsh lighting is the tricky part.

> draw:extrusion-first-light-harsh [N 1309]
> -----------------------------------------
>                 Key: OFFICE-2200
>                 URL: http://tools.oasis-open.org/issues/browse/OFFICE-2200
>             Project: OASIS Open Document Format for Office Applications (OpenDocument) TC
>          Issue Type: Bug
>          Components: Graphics
>    Affects Versions: ODF 1.0, ODF 1.0 (second edition), ODF 1.0 Errata 02
>            Reporter: Robert Weir 
>            Assignee: Svante Schubert 
>             Fix For: ODF 1.0 Errata CD 5
> Submitter ID
>     GB-26300-328
> Nature of defect
>     Clarification Required
> Document
>     ISO/IEC 26300:2006
> Clause
>     9.5.2
> Page
>     328
> Description of issue
> It is stated "The draw:extrusion-first-light-harsh attribute specifies if the primary light is harsh".
> This is the only commentary on this element: it is not sufficiently specified to implement at all, let alone implement interoperably.
> Proposal
> Provide a sufficient description of how this element is to be processed, or clarify that its implementation is application-dependent.

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