Has anyone tried to extend Spatial with a 3D primitive?

Question

Has anyone tried to extend Spatial with a 3D primitive that for example can model buildings and tunnels? I am trying to add the polyhedron primitive next to the existing point, line, polygon model. I just want to hear some tips or ideas...

Answer 1

The plan is to make a new GType and new stored functions that recognize this GType.
A polyhedron could be of type 3008,3D and 8=polyhedron(=new). The elem_info
and ordinates contain multiple planes. Self-created stored functions would be
able to recognize this GType, e.g. area3D should give the sum of the areas of all the
faces of the polyhedron and should also work on Gtype=3003 and give the real area
of a 3D polygon instead of the projection.I wouldn't suggest this methodology if you are considering using any spatial indexing or
functions with your data.
There is a mechanism Oracle Spatial has for defining custom datatypes. It should only
be used with custom apps, i.e. it won't be usable in the context of applications that know
about Oracle Spatial data types.
The mechanism allows you to define you own element using an element type of 0, and using
the interpretation to define what you are looking at. You would also include an a supported
element type that approximates your geometry, and that element is the one that is indexed,
and the gtype entered is associated with that geometry. Your private functions could access
the 3d geometry when required. For instance, you want to have a 3d cube. It might look like this:
sdo_gtype=3002
sdo_elem_info=(1,2,1, 7,0,1, 22,0,2 etc.
sdo_ordinates=(0,0,0,2,2,2, 0,0,0,2,0,0,2,2,0,0,2,0,0,0,0, 2,0,0,2,0,2,2,2,2,2,2,0,2,0,0, etc
the 1,2,1 in the elem info array corresponds to a 3d line string that when indexed with a minimum bounding
volume encloses the 3d cube. The 0,0,0 and 2,2,2 in the ordinate array stored as the line string when indexed
include the bounds of the cube. Next in the elem info array are 7,0,1. The 7 means offst 7 in the ordinate array
and in this example is fixed. Next the 0 tells Oracle Spatial to ignore this element. The interpretation of 1 you define,
the number could be anything. Since it is my example, I'll say the 1 means this is the definition of the first face in the
x,y plane (i.e. the front face of the cube which faces me). I've set the ordinate array with the coordinates of that face.
Next in elem info comes 22,0,2 which is starting at offset 22 there is another element that Oracle spatial should ignore
(element type 0), and next comes 2, which might mean this is the second face definition, that I've defined as the right
hand side y,z plane.
etc.
The meaning of the interpretation value is only limited by your imagination.
Note while you can index three dimensions if you want, the only spatial functionality that supports 3d is a spatial
index and a filter query, and some lrs functions. You will not be able to run any operator except for SDO_FILTER if you
have a 3d index, and all spatial functions will only work on 2d.
Do not define your own gtype and expect to use spatial. it will not work.