Hi, Im new to babylon, just wondering why babylon has plotted y axis in upward direction as it is ‘z’ axis in general?
Hello! Having the Y or Z axis up is just a convention, since the maths behind computer graphics don’t really care about the “physical” side of things. If someone really wanted, they could even put the X axis as up! Babylon’s coordinate system is inspired by DirectX, which uses a left-handed coordinate system with the y axis as up ( Coordinate Systems (Direct3D 9) - Win32 apps | Microsoft Docs ). And having the Y axis as up is pretty common in other graphic libraries, like OpenGL (
LearnOpenGL - Coordinate Systems ).
From my graphics programming experience, the Z axis as up convention is more common in CAD applications (like Blender, 3DSMax, etc). It can be a bit annoying to have to remember all these different systems and have to accustom yourself to a different one, but that keeps your brain fresh, at least! 
2 Likes
Thank you carol, im even new to 3d coordinate systems 
Thank you for your time. 
I thinkl it is probably a reasonable assumption that the driver behind the development of computer graphics was games. Originally these where 2D in the plane of the screen. Everbody knows 2D coordinates are x and y. It follows that x and y were used to place items horizontally and vertically on the screen. As 3D games were introduced it made sense to keep the existing x, y convention and make z the third coordinate perpendicular to the screen. Hence the y up system.
Once graphics were good enough up stepped designers and architects to develop CAD systems. Since there backgrounds would include mathematics they wanted a system to fit the maths conventions, eg z up.
As usual different backgrounds and experience lead to different ways of describing the world. Now there are two 3D axes coordinate systems. WAIT, there are actually four, nobody has yet mentioned left and right handed systems!!
1 Like