Dear Iulio, [...] >> We are planning a educational project for water management >> networks in >> Ethiopia > > Good luck for your project, especially because it is educational.
Thank you! [...] > You said do not have a precise vertical network, even so you can use GPS and > mix it with traditional topographic leveling for critical nstallations. > > I do not know your project extension and precision requirements but i believe > you can use GPS and a relative geoid undulation to correct the geometric > height differences and get an almost orthometric height. > I have used EGM2008 and this way and get realy good results. > Pay attention on EGM2008 if you have no gravitational anomalies in your > working area and for sure this simple differential model will give you > acceptable results. > Hj - Hi = (hj - hi) - ( Nj - Ni ) > H=orthometric > h=geometric > N=geoid ondulation > > http://www.fig.net/pub/athens/papers/ts07/ts07_8_roman.pdf Thanks you, since we are talking about small networks, I think we should really get good results, I appreciate you backup my guess. I will read throught the documentation, thanks! Best regards, Andrea > > best regards, > > julio menezes > _______________________________________________ > This message is sent to you from [email protected] mailing list. > Visit http://lists.osgeo.org/mailman/listinfo/foss-gps to manage your > subscription > For more information, check http://wiki.osgeo.org/wiki/FOSS-GPS _______________________________________________ This message is sent to you from [email protected] mailing list. Visit http://lists.osgeo.org/mailman/listinfo/foss-gps to manage your subscription For more information, check http://wiki.osgeo.org/wiki/FOSS-GPS
