ElevationGrid

[Neil Woodhouse <N.Woodhouse@earth.leeds.ac.uk>]

Hi,

I put on fireproof clothing, get hold of a very large cat, throw it amongst the pigeons and say:  :-)

The ElevationGrid node is cumbersome and a bit constrained except for the most simplist of uses.

Viz:

A scenario. Which exists.

As a Geologist, with an interest in using VRML to produce teaching aids etc, i spend a lot of my time out in the field surveying.

So i come back from the field with a data set and wish to show a group of students the area i have been working in, and i want to produce this in VRML  ala map style. After some thought i realise that i need three ElevationGrids to get my work over.

1. A base ElevationGrid ( say 1 sq Km spaced every 100m = 100 points )
2. The ElevationGrid for my data. ( taken every 50m = 200 points )
3. An ElevationGrid which contains the equivalent data points as the base grid ( 100 points. )
4. Place contour lines between points of equal height.
5. Place a scale bar within the browser to get an idea of scale.

Sooo now for the questions.

If i read the spec right do i take it that the 0,0 co-ord is the top-left of the data set?. If this is the case then for British Ordnance survey maps the ElevationGrid ain't much use. 

Does the same problem exist for the DEM. How is this got around.
Contouring. How can this problem be tackled. Do i have to use the IndexLineSet, if so this means that i have to enter the main data set TWICE!!! and is VRML capable of contouring anyway. It's not mentioned at all!!.


Scale bars. Why doesn't VRML have a standard set of scale bars. Not all of us are interested in making imaginary worlds where scale doesn't matter. 

So can anyone suggest or give some thought to a few additions or amendments to the ElevationGrid.

Eg. A ContourGrid spec.
    A ScaleBar spec

Can we ( GeoVRML ) look into the different co-ordinate systems used by various countries and formulate some form of CoOrd spec.

All this, and i haven't even mentioned laying on the colour coding for the surface geology  LOD's etc, etc, ad naseum.

I await Napalm :-)

Best Wishes,

Neil Woodhouse
School of Earth Sciences
University of Leeds
UK.



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