I have a text file of several surveyed ponts throughout my model. I can select one of these points in my model and specify the coordinates of East/West, North/South, and elevation from this file, but how do I determine the angle from project north to true north from these surveyed points?
The survey points come with a True North orientation and they represent absolute values (conected to a world system)
The Project North is an easy way to rotate the building so as its grids to be horizontal and vertical in order to allow a quick design process - it works with relative values...
People that worked in Autocad understand it better : WCS versus UCS
In practice I use two methods:
1. when I have the project in an advanced phase of work and I want then to insert a Toposurface.
in Site Plane view, True North, insert Toposurface. The building will appear as in Project North (horizontal-vertical orientation).
Select the Project Base Point (use filter in order to separate it from the Survey Point Internal), unclip it and move it at a grid intersection (or a corner of the building). Draw then, a Reference Plane through the grid intersection at an angle the building is orientated on site.
Measure the angle with horizontal (angular dimension) .Click onProject Base Point and at Align to True North put the measured angle value.The whole will rotate .
Now , select only the Toposurface and Rotate back with the measured angle ...
2. I begin with the Toposurface- no project yet...
make the Toposuface
draw in Site Level (True North) a Model Line with the desired orientation of the building
in Level 1 (Project North) Manage >Rotate Project North >Align Selected Line ...the Model Line will snap to horizontal or vertical ...