Since Google Earth geolocation was replaced with Digital Globe, I’ve been setting up the terrain model using Digital Globe and getting pretty good contours and, thank gosh, elevations. But the distance mapping is quite at variance from GE. I don’t know where this inaccuracy lies, but I suspect Digital Globe, as my ground-truthing with Google Earth has been pretty accurate. Digital Globe in my models is off by 5% to 7%, and measuring along different xy axes produced different % errors. That’s actually a lot if your using your model for rough take-offs.
The pictures from Digital Globe are so homely, I don’t use them. I project a GE image on top of them and then struggle to achieve a good fit, scaling every which way.
I’ve decided that since the GE scale legend is pretty accurate, I’ll use it for my ‘standard’. That is, I adjust the Digital Globe map to fit the GE map.
It’a not a happy marriage.
I wonder if ThomThom, who has done a lot of geo-referenced work in his other life (bless that man) might offer some tips, for example: Is there a standard deviation we can fit to, and is it true that GE orthometry is that much better than Digital Globe, and how does he go about getting this all to work?
Thanks for any help or advice.