# Geometry :

Subject: [ggl] boost geometry rtree
From: Barend Gehrels (barend)
Date: 2011-07-14 03:38:11

>
> Still within don't work for boxes with different point types because
> it can't convert between box<point> and box<point_xy>.

It is fixed, thanks for the message. It was a small error. I added it to
the unit tests. It is committed to Trunk

>
>
> The same with geometry::convert :

Will look at that in more detail when I look to Hartmut's question (also
for assign/convert).

>>
>>> (http://mathworld.wolfram.com/Content.html) because in dimensions
>>> greater than 4 3d volume may have different meaning. Hypersurface of
>>> a 4d object is 3-dimensional and someone may call it the volume,
>>> like 2d surface of a 3d object is called the surface.
>>>
>>> I use also a function calculating the margin of a box (this term is
>>> taken from: R*tree: An Efficient and Robust Access Method for Points
>>> and Rectangles by Beckmann at al.). I assumed that this is nD
>>> hypersurface so for 2d it's the perimeter of a box, for 3d it's
>>> surface, for 4d it's 3d hypersurface etc.

>>
>>
>> OK, good idea. If "margin" is the right term for that, we should use
>> that. Thanks.
>
> In the original paper 'margin' refers to 'perimeter' but they only
> describe 2d. I've searched for the meaning of this in 3d but didn't
> find anything. I think the best is to check which one gives best
> results in dimensions greater than 2 - perimeter or hypersurface.

OK, I will look/ask for this in more detail. If anyone on this list know
the very right term, it is welcome. So the question is:

"content" means: length-in-1-D, area-in-2-D, volume-in-3-D
"XXX" means: perimeter-in-2-D, area-in-3-D

where "XXX" might be margin. The term "content" is quite difficult to