yang686526

need help about isometries
need help about isometries
it's a week i have been searching for a solution, now i feel a urge to post my question!
i am currently modifying odamfcapp - god bless it - in order to make my own utility to be used internally in the company i work for. working in the field of sea cartography, they use to split a north-up overall map (i.e. north is at the top of the map) into a series of boxes at a given scale. each box is made parallel to a piece of the route followed by the ship, so it get the same orientation with respect to north. the side perpendicular to that piece of route always measures 850 units. look at the first picture. the red line is just a visual reference to the origin of each xref. when they are geo-referenced, it coincides with the intersection between the equator (latitude 0 n) and the greenwich meridian (longitude 0 e), and they all coincide.
the final sheet, however, need boxes to be rotated and traslated, in order to acquire an orientation parallel to the sheet side. a classic case of isometry. each xref is quite complex and not univocally defined; however, each separate box contains a clip overlapping the box sides, that defines what part of the file has to be visible. that's why i identify each box with the coordinates of that clip thanks to mr. novikov at

forget it. i found the way. i found useful reading , which i hadn't found in my previous searches.
i used setblocktransform with each block reference to set the correct rotation, but setposition to operate the translation.
this way is poorly intuitive, if anything better is appliable. i agree with palithius.