[x3d-public] X3DOM Documentation: Gamma Correction

[Andreas Plesch]

One, I think important, reason to allow a scene author to choose gamma
correction for a scene with a node such as Environment or field value
is that only the author knows how colors and textures in the scene are
supposed to be used. Only the author knows if colors provided in the
scene are defined for a linear color space or a srgb color space.

Another, unrelated, question is if it should be possible to allow
mixed use of color spaces. For example, shapes with a PhysicalMaterial
could use a linear color space, while other shapes could use a srgb
space. That means, instead of a global gamma correction field, there
could be a field with a more local scope. This is a larger change and
perhaps too complex.

-Andreas

On Wed, Sep 2, 2020 at 11:25 AM Don Brutzman <brutzman at nps.edu> wrote:
>
> Thanks Michalis and everyone for renewed scrutiny on gamma and SRGB.
>
> Meanwhile a small point: we don't need to worry about the potential burden of adding another node (i.e. Environment).
>
> There is already a modest number of global capabilities that are defined in Scene Access Interface (SAI).  So gamma correction options can be hung in there somewhere.  If ever needed by an author (likely rare) they might nevertheless access the property via Script node.
>
> ==============================
> Extensible 3D (X3D) Part 2: Scene access interface (SAI)
> 6.3 Browser services
>
> https://www.web3d.org/documents/specifications/19775-2/V3.3/Part02/servRef.html#BrowserServices
>
> 6.3 Browser services
> 6.3.1 Introduction
> 6.3.2 getName
> 6.3.3 getVersion
> 6.3.4 getCurrentSpeed
> 6.3.5 getCurrentFrameRate
> 6.3.6 getSupportedProfiles
> 6.3.7 getProfile
> 6.3.8 getSupportedComponents
> 6.3.9 getComponent
> 6.3.10 getExecutionContext
> 6.3.11 createScene
> 6.3.12 replaceWorld
> 6.3.13 importDocument
> 6.3.14 loadURL
> 6.3.15 setDescription
> 6.3.16 createX3DFromString
> 6.3.17 createX3DFromStream
> 6.3.18 createX3DFromURL
> 6.3.19 updateControl
> 6.3.20 registerBrowserInterest
> 6.3.21 getRenderingProperties
> 6.3.22 getBrowserProperties
> 6.3.23 changeViewpoint
> 6.3.24 print/println
> 6.3.25 dispose
> 6.3.26 setBrowserOption
>
> ==============================
> Extensible 3D (X3D) Part 2: Scene access interface (SAI)
> 6 Services reference, 6.3.26 setBrowserOption
>
> https://www.web3d.org/documents/specifications/19775-2/V3.3/Part02/servRef.html#setBrowserOption
>
> parameters:     SAIBrowserRef, SAIString, SAIObject
> returns:        SAIBoolean
> errors: SAI_INVALID_OPERATION_TIMING
> events: None
> buffered:       No
> external:       Yes
>
> The setBrowserOption service allows setting options defined in 9.2.4 Browser options in ISO/IEC 19775-1. The name field shall be one of the defined names in Table 9.2 in ISO/IEC 19775-1. This service shall return an SAIBoolean value indicating whether the change request was successful. A browser is not required to support dynamic changes to any options. If a browser option is not supported, a value of FALSE shall be returned.
>
> ==============================
> Extensible 3D (X3D) Part 2: Scene access interface (SAI)
> 6.4 Execution context services
>
> https://www.web3d.org/documents/specifications/19775-2/V3.3/Part02/servRef.html#ExecutionContextServices
>
> 6.4 Execution context services
> 6.4.1 getSpecificationVersion
> 6.4.2 getEncoding
> 6.4.3 getProfile
> 6.4.4 getComponents
> 6.4.5 getUnits
> 6.4.6 getWorldURL
> 6.4.7 getNode
> 6.4.8 createNode
> 6.4.9 createProto
> 6.4.10 namedNodeHandling
> 6.4.11 getProtoDeclaration
> 6.4.12 protoDeclarationHandling
> 6.4.13 getExternProtoDeclaration
> 6.4.14 externprotoDeclarationHandling
> 6.4.15 getRootNodes
> 6.4.16 getRoutes
> 6.4.17 dynamicRouteHandling
> 6.4.18 dispose
>
> ==============================
>
> On 9/1/2020 12:42 PM, Michalis Kamburelis wrote:
> > 9. [...] We need to talk and figure out what is best. Opinion from other browser implementors is necessary to make a proper decision here, IMHO. I'm leaning toward
> >
> >    Environment {
> >      SFString gammaCorrectionDefault "DEFAULT" # ["DEFAULT", "NONE", "LINEAR"]
> >    }
> >
> >    Where "DEFAULT" == browser-specific behaviour.
> >
> >     So it is not a perfect solution (because we avoid specifying the default), but it allows authors to force/disable gamma correction if desired.
> [...]
>
> all the best, Don
> --
> Don Brutzman  Naval Postgraduate School, Code USW/Br       brutzman at nps.edu
> Watkins 270,  MOVES Institute, Monterey CA 93943-5000 USA   +1.831.656.2149
> X3D graphics, virtual worlds, navy robotics http://faculty.nps.edu/brutzman



-- 
Andreas Plesch
Waltham, MA 02453