pakachunka wrote: > Thank you again Thomas! > > Is there some text referent to "bounding boxes" I can read? Is there > some literature to follow what you are saying? > > Just to make you understand better what I am doing: I am making a > driver for a new type of low cost tablet for linux. Tablets in general > have problems with linearization, so I am creating a way to convert > the (u,v) voltages measured by the tablet, into (x,y) position in the > screen. For that I need a linearization procedure, during which the > user put the tablet stylus over marks in the screen. That is when the > mesh of triangles mentioned before are created. After the mesh is > ready and set, I use some Conformal Transform to transform the (u,v) > voltages into (x,y) positions, based on the mesh. For that I need to > determine in which triangle of the mesh the (u,v) voltages are contained. > > Everything needs to run in a PIC microcontroller. > > The tablet aims education and will be freeware. > > Thanks! > > Tor
Quick search on Google for "bounding box" turns up: http://en.wikipedia.org/wiki/Minimum_bounding_rectangle Why a triangle mesh though? If you collected 9 (u,v) data points from the user (corners, midpoints, center), can't you just use linear interpolation for the values based on those points? Or you could figure out a mathematical formula that applies some sort of quadratic curve that better fits the display. Collect a whole bunch of sample (u,v) -> (x,y) values and plug 'em into Excel and stare at and fiddle with the numbers for a while. There are always patterns to be found. If you can avoid the triangle mesh with a few quadratic curves, it would, IMO, be worth the effort and generally perform well. Collecting data points from the user that form rectangles seems simpler to me than building a big ol' triangle mesh. Simple typically works better (not always the case). But, hey, I'm not an electrical engineer. -- Thomas Hruska CubicleSoft President Ph: 517-803-4197 *NEW* MyTaskFocus 1.1 Get on task. Stay on task. http://www.CubicleSoft.com/MyTaskFocus/
