i wan’t to render a 3d scene wich represents a place that exists on earth (for example, my house, the garden, etc…)
How to make that all the things that will be on the screen are looking to the real objects (i am talking about Height,Width)
In the reality, we use some units when talking about height and width, but if i’m not wrong with opengl (and maybe 3d programming in general) we do not use any unit, so how to do ?

i’m not sure that the question is well asked but if anyone understand what i mean, please help me.


Units in OpenGL are… well, they’re units… it’s up to you what measurement you use. For example, if you want 0.1 world space units to be 1ft, go ahead
It all depends on how you want to set your scale. It helps to look at your frustum setup and use an according scale though, e.g. if your far frustum plane is at 100.0, and 0.1 is 1ft in your engine, then you have a visibility range of 1000ft.
Find a ratio that is good for you, that looks good with your perspective setting, and build your models accordingly.

tanks, i’ve got the point,
your explaination about frustrum helps me.