TChart coordinate systems

[wp]

I am a bit confused about the TAChart coordinate systems. The documentation reads:

- Axis coordinates (known in some other applications as object coordinates) -- this is the "raw" coordinate values obtained from the data...
- Graph coordinates (aka world coordinates) are converted from the axis coordinates using axis transformation, such as logarithmic scale. Graph coordinates are common for all objects in the chart.

What confuses me is the phrase "world coordinates" attributed to the second point, "graph coordinates".

In my view, "world coordinates" refer to the data in their own units, and "object" and "world" coordinates are the same. So, if my data range between 1 and 10 meters, these numbers are the "world coordinates". When I want to plot these data logarithmically I apply a log transform and get numbers between lg(1)=0 and lg(1)=1 which are plotted in the diagram. Therefore, I would call the values 1...10 "axis coordinates" because that's what's written on the axis, and the numbers 0...1 "graph coordinates" because that is what is actually plotted. This is in agreement with the doc, but the phrase "world coordinates" should not be where it is.

[Ask]

Traditionally, in geometry and computer graphics "world coordinates" refer
to a global coordinate system common for all objects,
as opposed to "object" or "local" coordinates.

http://en.wikipedia.org/wiki/Coordinate_system#Change_of_coordinates

http://www.cse.ohio-state.edu/~gurari/course/cis681/cis681Ch8.html

http://www.jimbrooks.org/web/opengl/tutorials/#Coordinate%20Systems

(or just google for "world coordinates").

Anyway, although I am quite confident in this meaning,
I am not a native English speaker.
So if you think this terminology is incorrect, I can drop it.

[wp]

I know "object" and "local" coordinates mainly from CAD. Maybe the confusion lies in the sentence

"world coordinates" refer to a global coordinate system common for all objects

Of course, after transformations there is only one coordinate system which is applied to all objects. Therefore, you call this "world" coordinates. To me, on the other hand, the "world" refers to the data BEFORE transformations - as I said above to data in meters for example, not to their logarithms.

I am not a native English speaker.

I'm not either. Maybe a native English speaker out there could comment.