Re: [office] surface plots

["Andreas J. Guelzow" <aguelzow@pyrshep.ca>]

On Fri, 2009-07-31 at 12:49 +0200, Ingrid via Eike Rathke wrote:
> > In any case, at least in North America (and I am pretty sure also in
> > Germany 25 years ago) the z-axis would usually be used for height with x
> > and y for the base. See for example
> > http://reference.wolfram.com/mathematica/tutorial/ThreeDimensionalSurfacePlots.html
> > http://www.omatrix.com/manual/mesh.htm
> > http://homepages.see.leeds.ac.uk/~lecjm/Teaching/IDL_course/Notes/notes/node27.html
> >   
> Two already existing implementations of ODF use a left handed coordinate 
> system with horizontal x axis and vertical y axis.

Well, there are lots of other places where ODF has chosen to use unusual
definition. I guess one can always trnaslate from ODF's coordinate
naming to a more reasoanble one.
> >
> >   
(...)
> >
> > I would think along the following line:
> >
> > surface -- this class of charts is used for surface and contour charts.
> > A single series specifies a rectangular table cell area. Each column of
> > this area corresponds to a specific x-value while each row corresponds
> > to a specific y-value. The cell at the intersection of the column and
> > row gives the altitude (z-value) at the specific location.
> >
> > The x-values are specified as the first chart:domain. If no chart:domain
> > is given they default to 1 for the first column, 2 for the second
> > column, etc.
> >
> > The y-values are specified as the second chart:domain. If no or only one
> > chart:domain is given they default to 1 for the first row, 2 for the
> > second row, etc.
> >
> > In case of chart:three-dimensional="false" a contour map is shown. Each
> > altitude value is located on a 2 dimensional Cartesian coordinate system
> > with horizontal x axis and vertical y axis.  Axis elements with
> > dimension 'x' and 'y' are used to desribe the visible axes. A third axis
> > element with chart:dimension="z" is used to define the range and
> > separation for the colours representing the altitude ranges.
> >
> > In case of chart:three-dimensional="true" a 3-dimensional surface plot
> > is shown in a right handed coordinate system with 3 axes of dimensions
> > 'x', 'y' and 'z'. (In this case we would need some specification method
> > for the view point and view direction.)
> >   
> No, this is completely not what was intended with the surface chart 
> definition in ODF. And it stands in conflict with the former definition:
> "the data points are interpreted as tabular data, where *each value 
> defines a 'height'* at a specific grid location"

I really don't understand how this conflicts. In my sugestion the
datapoints of the series define heights as a specific grid location. In
fact my suggestion use tabular data (ie. a table) to define the heights
(while yours seems to use a collection of vectors, clearly not tabular
data).

For virtually all chart types ODF allows to specify several plots in the
same chart in fact it allows several plot types). I fail to see how your
interpretation would allow to specify 2 surface plots i teh same
coordinate system.

Andreas
> 

> 
-- 
Andreas J. Guelzow <aguelzow@pyrshep.ca>