I am presently working on dynamic map layout. This tool is like ArcMap layout. I have workedout all the mapping tools like north arrows, scale bars, text, images. But in that i want to draw grids and graticules. I have drawn utm grid (means we can draw the grid lines as straight lines based on the physical distance), but i don't know how to work with geographic graticules. Because graticules means the lines are comes as curved lines. Hence i dont know how to draw the curved lines based on the different projections. Can anybody give me suggessions about the graticules drawing. please give the conceptual and programming ideas. And one more question is that how to make the dynamic graphicpath control as transperent in vb.net. Because after creating the grid control it is overlaying on the mapcontrol. help me plz.
without exactly knowing how your code works it's a bit hard to give you advice.
Anyway, the way I would do it is to use
ProjToPixel() : Void public Converts a point in projected map units to a point in screen coordinates. briefly described in [www.mapwindow.org]
The actual call to this Sub looks in VB.net like this:
AxMap.View.ProjToPixel(ByRef Long, ByRef Lat, pix_x As Integer, pix_y As Integer)
Supply Lat/Long and retrieve pixels x/y for that point. The pixel x/y are map window screen pixel coordinates.
You could avoid the call to ProjToPixel completely if you use the following:
As far as curving of meridians and parallels is concerned, you are in luck because Earth is so big and these curved lines can be quite accurately approximated by straight line segments.
I would divide each into sections of about 1 Km length (about 0.01 degree) and string these sections together as PolyLines. I would add these to a layer (shapefile) for the graticule and use that in your print layout.
Of course, you may draw these onto a drawing layer instead.
Have you taken a look at the MapWindow layout plug-in? Its a complete map layout system. It doesn't have graticules yet but its on my list of things to add to it.