Re: Map Calibration (WAS: RE: GpsDrive changes)

In OziExplorer you can use up to nine (IIRC) points to calibrate a map. 
You load your scanned image, or whatever, click a known point on the map 
and enter the lat and lon (or UTM grid or whatever, there are multiple 
formats) and repeat for as many points as you need. If your map is not 
distorted at all then three points are probably enough. If the scan 
comes from a wierd projection or is an oblique angle air photo 
(satellite photo) then you need more.

I don't think that reading the current position from the GPS has much 
use in map calibration as that can only define one point. In any case 
you are probably not in the area that you are calibrating the map for if 
you are preparing for a future trip, or preparing a map to download a 
track to for example.

GPSman has some useful features, an app combining the features of 
GPSDrive and GPSMan would just about do the trick.

Chris

Christopher Jastram wrote:

> Does anybody have ideas for easy map calibration?
>
> My current idea; display the map, and let the user pick the current 
> location on the map by click or moving a crosshair.  Then, the program 
> reads the current lat/lon from the gps device, and calibrates the map 
> accordingly.  You'd have to set the scale, or perhaps add "calibration 
> points" at different geographic points, and the program would figure 
> out the scale automatically.
>
> Shouldn't be too hard?  (It's early in the morning, so I might not be 
> thinking things through properly)
>
> Chris Jastram
> cej102937
>
> Chris Harris wrote:
>
> > > Objections?  Comments?  Should I change the name?  GpsDrive-ng?
> >
> >
> >
> > Hi,
> >
> > I'd like lots of things; I guess the easiest thing to say is to ask 
> > for a clone of OziExplorer for Linux. I hope that is not swearing!
> >
> > The main things for me are; easy map import and calibration, from 
> > scanned paper maps; upload/download routes, waypoints, tracks etc. 
> > to/from the GPS; Point and click creation of waypoints.
> >
> > I live in a remote corner of the world so your free NASA vector 
> > charts etc. are no use to me. The ability to use C-Map charts would 
> > be good.
> >
> > Cheers Chris
> >
> >
> >
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